THALES DIS AlS Deutschland XT55 Transmitter module for fixed / mobile applications User Manual XT55 56

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Document ID	585513
Application ID	IweELMUlfb8ZlrcCHqjs/A==
Document Description	Updated Usaer Manual
Short Term Confidential	No
Permanent Confidential	No
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Document Type	User Manual
Display Format	Adobe Acrobat PDF - pdf
Filesize	168.59kB (2107377 bits)
Date Submitted	2005-09-26 00:00:00
Date Available	2005-09-26 00:00:00
Creation Date	2005-08-18 11:58:27
Producing Software	Acrobat Distiller 6.0.1 (Windows)
Document Lastmod	2005-08-18 11:59:13
Document Title	XT55/56
Document Creator	Acrobat PDFMaker 6.0 for Word
Document Author:	GK30217

XT55/56
Siemens Cellular Engine
Version:
DocID:
02.96
XT55/56_hd_v02.96
XT55/56_hd_v02.96
Page 1 of 125
Hardware Interface Description
XT55/56 Hardware Interface Description
Confidential / Preliminary
18.08.2005
XT55/56 Hardware Interface Description
Confidential / Preliminary
Document Name:
XT55/56 Hardware Interface Description
Version:
02.96
Date:
August 18, 2005
DocId:
XT55/56_hd_v02.96
Status:
Confidential / Preliminary
General Notes
Product is deemed accepted by recipient and is provided without interface to recipient’s products. The
documentation and/or product are provided for testing, evaluation, integration and information
purposes. The documentation and/or product are provided on an “as is” basis only and may contain
deficiencies or inadequacies. The documentation and/or product are provided without warranty of any
kind, express or implied. To the maximum extent permitted by applicable law, Siemens further
disclaims all warranties, including without limitation any implied warranties of merchantability,
completeness, fitness for a particular purpose and non-infringement of third-party rights. The entire
risk arising out of the use or performance of the product and documentation remains with recipient.
This product is not intended for use in life support appliances, devices or systems where a malfunction
of the product can reasonably be expected to result in personal injury. Applications incorporating the
described product must be designed to be in accordance with the technical specifications provided in
these guidelines. Failure to comply with any of the required procedures can result in malfunctions or
serious discrepancies in results. Furthermore, all safety instructions regarding the use of mobile
technical systems, including GSM products, which also apply to cellular phones must be followed.
Siemens or its suppliers shall, regardless of any legal theory upon which the claim is based, not be
liable for any consequential, incidental, direct, indirect, punitive or other damages whatsoever
(including, without limitation, damages for loss of business profits, business interruption, loss of
business information or data, or other pecuniary loss) arising out the use of or inability to use the
documentation and/or product, even if Siemens has been advised of the possibility of such damages.
The foregoing limitations of liability shall not apply in case of mandatory liability, e.g. under the
German Product Liability Act, in case of intent, gross negligence, injury of life, body or health, or
breach of a condition which goes to the root of the contract. However, claims for damages arising from
a breach of a condition, which goes to the root of the contract, shall be limited to the foreseeable
damage, which is intrinsic to the contract, unless caused by intent or gross negligence or based on
liability for injury of life, body or health. The above provision does not imply a change on the burden of
proof to the detriment of the recipient. Subject to change without notice at any time. The interpretation
of this general note shall be governed and construed according to German law without reference to
any other substantive law.
Copyright
Transmittal, reproduction, dissemination and/or editing of this document as well as utilization of its
contents and communication thereof to others without express authorization are prohibited. Offenders
will be held liable for payment of damages. All rights created by patent grant or registration of a utility
model or design patent are reserved.
Copyright © Siemens AG 2005
Trademark notices
MS Windows® is a registered trademark of Microsoft Corporation.
SiRFDemo Software and SiRFstar are registered trademarks of SiRF Technology Inc., San Jose,
California.
Section 4.2, 4.3.1, 4.8 and 9 used with the permission of SiRF Technology, Inc., San Jose, California
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Contents
Document History .........................................................................................................8
Introduction .................................................................................................................11
1.1 Supported Software and Hardware Releases .....................................................11
1.2 Related Documents .............................................................................................12
1.3 Terms and Abbreviations.....................................................................................13
1.4 Type Approval......................................................................................................17
1.5 Safety Precautions...............................................................................................19
Product Concept .........................................................................................................21
2.1 XT55/56 Key Features at a Glance .....................................................................22
2.2 Circuit Concept ....................................................................................................25
GSM Application Interface .........................................................................................27
3.1 GSM/GPRS Operating Modes .............................................................................27
3.2 Power Supply.......................................................................................................29
3.2.1
Power Supply Pins on the Board-to-Board Connector...........................29
3.2.2
Minimizing Power Losses ......................................................................30
3.2.3
Monitoring Power Supply .......................................................................30
3.3 Power Up / Down Scenarios ................................................................................31
3.3.1
Turn on the GSM Part of XT55/56 .........................................................31
3.3.1.1 Turn on the GSM Part of XT55/56 Using the Ignition Line GSM_IGT
(Power on) .............................................................................................32
3.3.1.2 Timing of the Ignition Process................................................................33
3.3.1.3 Turn on the GSM Part of XT55/56 Using the GSM_POWER Signal .....34
3.3.1.4 Turn on the GSM Part of XT55/56 Using the RTC (Alarm Mode) ..........34
3.3.2
Turn off the GSM Part of XT55/56 .........................................................35
3.3.2.1 Turn off GSM Part of the XT55/56 Module Using AT^SMSO ................36
3.3.2.2 Emergency Shutdown Using GSM_EMERGOFF Pin ............................37
3.3.3
Automatic Shutdown ..............................................................................38
3.3.3.1 Temperature Dependent Shutdown.......................................................38
3.3.3.2 Temperature Control during Emergency Call ........................................39
3.3.3.3 Undervoltage Shutdown if Battery NTC is Present ................................39
3.3.3.4 Undervoltage Shutdown if no Battery NTC is Present ...........................40
3.3.3.5 Overvoltage Shutdown...........................................................................40
3.4 Automatic GPRS Multislot Class Change ............................................................41
3.5 Charging Control of the GSM Part .......................................................................42
3.5.1
Battery Pack Characteristics..................................................................44
3.5.2
Recommended Battery Pack Specification............................................45
3.5.3
Implemented Charging Technique.........................................................46
3.5.4
Operating Modes during Charging.........................................................48
3.5.5
Charger Requirements...........................................................................49
3.6 Power Saving.......................................................................................................50
3.6.1
No Power Saving (AT+CFUN=1) ...........................................................50
3.6.2
NON-CYCLIC SLEEP Mode (AT+CFUN=0) ..........................................50
3.6.3
CYCLIC SLEEP Mode (AT+CFUN=5, 6, 7, 8) .......................................51
3.6.4
CYCLIC SLEEP Mode AT+CFUN=9 .....................................................51
3.6.5
Timing of the GSM_CTS Signal in CYCLIC SLEEP Modes ..................51
Wake up XT55/56 from SLEEP Mode .................................................................53
3.6.5.1 Wake-up via /RTS0 and RTS1 (if AT+CFUN=0 or AT+CFUN=9)..........54
3.7 Summary of State Transitions (Except SLEEP Mode).........................................55
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3.8
3.9
RTC Backup for GSM Part of XT55/56 ................................................................56
Serial Interfaces of the XT55/56 GSM Part .........................................................57
3.9.1
Features Supported on the first Serial Interface of GSM Part (ASC0)...57
3.9.2
Features Supported on the second Serial Interface of GSM Part (ASC1)
...............................................................................................................58
3.9.3
ASC0 and ASC1 Configuration..............................................................58
3.10 Audio Interfaces...................................................................................................59
3.10.1 Microphone Circuit .................................................................................60
3.10.2 Speech Processing ................................................................................61
3.10.3 DAI Timing .............................................................................................61
3.11 SIM Interface .......................................................................................................63
3.11.1 Requirements for Using the GSM_CCIN Pin .........................................64
3.11.2 Design Considerations for SIM Card Holder..........................................65
3.12 Control Signals ....................................................................................................66
3.12.1 Inputs .....................................................................................................66
3.12.2 Outputs ..................................................................................................67
3.12.2.1 Synchronization Signal ..........................................................................67
3.12.2.2 Using the GSM_SYNC Pin to Control a Status LED..............................68
3.12.3 Behavior of the GSM_RING0 Line (ASC0 Interface only) .....................70
GPS Application Interface ..........................................................................................71
4.1 Theory of Operation.............................................................................................71
4.2 Technical Data.....................................................................................................72
4.3 GPS Operating Modes.........................................................................................73
4.3.1
Trickle Power Mode ...............................................................................74
4.3.2
Comparison of Trickle Power and Push-to-Fix Mode ............................75
4.4 Power Supply of the XT55/56 GPS Part ..............................................................76
4.5 General Purpose Input/Output (GPIO) ................................................................76
4.6 Serial Interfaces of the XT55/56 GPS Part ..........................................................77
4.7 GPS Control Signals............................................................................................77
4.8 Receiver Architecture ..........................................................................................78
4.9 Operation Procedure ...........................................................................................79
4.10 Start-up Procedures.............................................................................................80
4.10.1 Coldstart.................................................................................................80
4.10.2 Warmstart ..............................................................................................80
4.10.3 Hotstart ..................................................................................................80
GSM and GPS Antenna Interfaces.............................................................................81
5.1 GSM Antenna Installation ....................................................................................81
5.1.1
GSM antenna Connector .......................................................................81
5.1.2
GSM Antenna Pad .................................................................................83
5.2 Installing the GPS Antenna..................................................................................83
5.3 Hirose Antenna Connector ..................................................................................84
Electrical, Reliability and Radio Characteristics......................................................88
6.1 Absolute Maximum Ratings .................................................................................88
6.2 Operating Temperatures......................................................................................88
6.3 Pin Description.....................................................................................................90
6.4 Power Supply Ratings .........................................................................................96
6.4.1
Current Consumption during GSM Transmit Burst ................................98
6.5 Electrical Characteristics of the Voiceband Part................................................103
6.5.1
Setting Audio Parameters by AT Commands ......................................103
6.5.2
Audio Programming Model ..................................................................104
6.5.3
Characteristics of Audio Modes ...........................................................105
6.5.4
Voiceband Receive Path......................................................................106
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6.6
6.7
6.8
6.5.5
Voiceband Transmit Path.....................................................................107
Air Interface of the XT55/56 GSM Part ..............................................................108
Electrostatic Discharge ......................................................................................109
Reliability Characteristics...................................................................................110
Mechanics..................................................................................................................111
7.1 Mechanical Dimensions of XT55/56 ..................................................................111
7.2 Mounting XT55/56 onto the Application Platform ..............................................113
7.3 Board-to-Board Connector.................................................................................115
Reference Approval ..................................................................................................117
8.1 Reference Equipment for Type Approval...........................................................117
8.2 Compliance with FCC Rules and Regulations (XT55 only) ...............................118
8.3 Compliance with FCC Rules and Regulations (XT56 only) ...............................119
Example Applications...............................................................................................120
10
List of Parts and Accessories..................................................................................124
Figures
Figure 1: Product label placed on XT55/56 module ............................................................... 11
Figure 2: Block diagram of serial interface concept ............................................................... 26
Figure 3: Power supply limits during transmit burst................................................................ 30
Figure 4: Power-on by ignition signal ..................................................................................... 32
Figure 5: Timing of power-on process if GSM_VDDLP is not used ....................................... 33
Figure 6: Timing of power-on process if GSM_VDDLP is fed from external source .............. 34
Figure 7: Deactivating GSM engine by GSM_EMERGOFF signal......................................... 37
Figure 8: Schematic of approved charging transistor, trickle charging and ESD protection .. 42
Figure 9: Battery pack circuit diagram.................................................................................... 44
Figure 10: Charging process .................................................................................................. 47
Figure 11: Timing of CTS signal (example for a 2.12 s paging cycle).................................... 52
Figure 12: Beginning of power saving if CFUN=5 or 7 ........................................................... 52
Figure 13: RTC supply from capacitor.................................................................................... 56
Figure 14: RTC supply from rechargeable battery ................................................................. 56
Figure 15: RTC supply from non-chargeable battery ............................................................. 56
Figure 16: Audio block diagram.............................................................................................. 59
Figure 17: Schematic of microphone inputs ........................................................................... 60
Figure 18: DAI timing on transmit path................................................................................... 62
Figure 19: DAI timing on receive path .................................................................................... 62
Figure 20: SIM card holder of DSB45 Support Box................................................................ 65
Figure 21: Pin numbers of Molex SIM card holder on DSB45 Support Box ........................... 65
Figure 22: GSM_SYNC signal during transmit burst.............................................................. 67
Figure 23: LED Circuit (Example)........................................................................................... 69
Figure 24: Incoming voice call................................................................................................ 70
Figure 25: URC transmission ................................................................................................. 70
Figure 26: Theory of operation ............................................................................................... 71
Figure 27: Example for current in Trickle Power mode .......................................................... 74
Figure 28: Comparing typical current in Trickle Power and Push-to-Fix mode ...................... 75
Figure 29: Example of LED circuit.......................................................................................... 78
Figure 30: Receiver architecture of the GPS receiver............................................................ 78
Figure 31: U.FL-R-SMT connector ......................................................................................... 81
Figure 32: Antenna pad and GND plane ................................................................................ 81
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Figure 33: Never use antenna connector and antenna pad at the same time ....................... 82
Figure 34: Restricted area around antenna pad..................................................................... 82
Figure 35: GPS antenna connector (U.FL-R-SMT connector) ............................................... 83
Figure 36: Mechanical dimensions of U.FL-R-SMT connector............................................... 84
Figure 37: U.FL-R-SMT connector with U.FL-LP-040 plug .................................................... 85
Figure 38: U.FL-R-SMT connector with U.FL-LP-066 plug .................................................... 85
Figure 39: Specifications of U.FL-LP-(V)-040(01) plug .......................................................... 86
Figure 40: Pin assignment (top view on XT55/56) ................................................................. 90
Figure 41: Typical current consumption vs. return loss in EGSM 900 network...................... 98
Figure 42: Typical current consumption vs. return loss in GSM 1800 network ...................... 99
Figure 43: Typical current consumption vs. return loss in GSM 1900 network ...................... 99
Figure 44: Peak current consumption during transmit burst in EGSM 900 network............. 100
Figure 45: Peak current consumption during transmit burst in GSM 1800 network ............. 100
Figure 46: Peak current consumption during transmit burst in GSM 1900 network ............. 101
Figure 47: Typical current consumption vs. return loss........................................................ 102
Figure 48: AT audio programming model............................................................................. 104
Figure 49: XT55/56 – top view ............................................................................................. 111
Figure 50: XT55/56 bottom view .......................................................................................... 111
Figure 51: Mechanical dimensions of XT55/56 .................................................................... 112
Figure 52: Mounting holes on XT55/56 ................................................................................ 113
Figure 53: Recommended dowel ......................................................................................... 114
Figure 54: Mechanical dimensions of Hirose DF12 connector............................................. 116
Figure 55: Reference equipment for approval...................................................................... 117
Figure 56: Block diagram of XT55/56 for SiRF Demo application........................................ 120
Figure 57: Block diagram of XT55/56 with AVL application (optional) ................................. 121
Figure 58: XT55/56 tracking phone with external µC (example application) ........................ 122
Tables
Table 1: XT55/56 key features ............................................................................................... 22
Table 2: GSM coding schemes and maximum net data rates over air interface.................... 24
Table 3: Overview of GSM/GPRS operating modes .............................................................. 27
Table 4: Power supply pins of board-to-board connector....................................................... 29
Table 5: AT commands available in Alarm mode................................................................... 35
Table 6: Temperature dependent behavior ............................................................................ 39
Table 7: Bill of material for external charging circuit............................................................... 43
Table 8: Specifications of recommended battery pack........................................................... 45
Table 9: Comparison Charge-only and Charge mode............................................................ 48
Table 10: AT commands available in Charge-only mode....................................................... 49
Table 11: Wake-up events in NON-CYCLIC and CYCLIC SLEEP modes............................. 53
Table 12: State transitions of XT55/56 (except SLEEP mode) .............................................. 55
Table 13: DCE-DTE wiring of 1st serial interface (GSM part) ................................................ 58
Table 14: DCE-DTE wiring of 2nd serial interface (GSM part)............................................... 58
Table 15: Signals of the SIM interface (board-to-board connector) ....................................... 63
Table 16: Pin assignment of Molex SIM card holder on DSB45 Support Box........................ 65
Table 17: Input control signals of the GSM part of the XT55/56 module................................ 66
Table 18: Coding of the status LED ....................................................................................... 68
Table 19: ASC0 ring signal.....................................................................................................70
Table 20: Return loss ............................................................................................................. 81
Table 21: Product specifications of U.FL-R-SMT connector .................................................. 84
Table 22: Material and finish of U.FL-R-SMT connector and recommended plugs ............... 85
Table 23: Ordering information for Hirose U.FL Series .......................................................... 87
Table 24: Absolute maximum ratings (GSM part) .................................................................. 88
Table 25: Absolute maximum rating (GPS part)..................................................................... 88
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Table 26: Operating temperatures ......................................................................................... 88
Table 27: Electrical description of application interface ......................................................... 91
Table 28: Power supply ratings (GSM part) ........................................................................... 96
Table 29: Power supply ratings (GPS part)............................................................................ 97
Table 30: Audio parameters adjustable by AT command .................................................... 103
Table 31: Voiceband characteristics (typical)....................................................................... 105
Table 32: Voiceband receive path........................................................................................ 106
Table 33: Voiceband transmit path....................................................................................... 107
Table 34: Air Interface .......................................................................................................... 108
Table 35: Measured electrostatic values.............................................................................. 109
Table 36: Summary of reliability test conditions ................................................................... 110
Table 37: Ordering information DF12 series ........................................................................ 115
Table 38: Electrical and mechanical characteristics of the Hirose DF12C connector .......... 115
Table 39: List of parts and accessories................................................................................ 124
Table 40: Molex sales contacts (subject to change) ............................................................ 125
Table 41: Hirose sales contacts (subject to change)............................................................ 125
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Document History
Preceding document: "XT55/56 Hardware Interface Description" Version 02.94
New document: "XT55/56 Hardware Interface Description" Version 02.96
Chapter
What is new
1.4
Deleted section “Compliance with international rules and regulations”.
3.3.1.1
Added further details of timing after power-up.
3.6.2, 0,
3.6.5.1
More detailed description of RTS wake-up.
3.12.2.2
Some text changes related to LED behavior in CYCLIC SLEEP mode.
8.2, 8.3
Deleted note on extra FCC certification for OEM products. Changed note on
recommendations for mobile and fixed devices. Added FCC labeling requirements.
Preceding document: "XT55/56 Hardware Interface Description" Version 02.06c
New document: "XT55/56 Hardware Interface Description" Version 02.94
Chapter
What is new
Throughout
document
Updated module images.
1.4
Added European Directives related to RoHS and WEEE. Updated version numbers
of several standards.
3.5.3
Described charging procedure if battery was deeply discharged.
3.12.3
Same description of RING line behavior for voice, data, fax.
7.2
Deleted screw and washer restrictions for mounting holes of XT55/56.
7.1
Updated figure “Mechanical dimensions of XT55/56”.
10
Siemens ordering numbers changed.
Preceding document: "XT55/56 Hardware Interface Description" Version 02.06b
New document: "XT55/56 Hardware Interface Description" Version 02.06c
Chapter
What is new
1.1
New chapter: Supported Software and Hardware Releases
2.1
New temperature range of GPS part: -25°C to +55°C.
2.2
Corrected GPS processor speed.
4.2
GPS receiver sensitivity has been changed from –138dBm to –142dBm + 2dB.
10
Updated Siemens ordering numbers of the XT55/56 modules.
Preceding document: "XT55/56 Hardware Interface Description" Version 02.06a
New document: "XT55/56 Hardware Interface Description" Version 02.06b
Chapter
What is new
4.2
XT55/56 is now supporting the ZDA protocol
8.3
Modified chapter, deleted note on required FCC certification for OEMs, antenna
value has been changes from 1.4dBi to 2.2dBI (GSM 850)
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Preceding document: "XT55 Hardware Interface Description" Version 02.06
New document: "XT55/56 Hardware Interface Description" Version 02.06a
Chapter
What is new
Throughout
document
Added XT56.
4.4
Notes about power supply of RTC and SRAM of GPS part.
5.3
Table 23: Corrected Hirose part number U.FL-LP-068.
10
Added Siemens ordering number for module XT56.
Preceding document: "XT55 Hardware Interface Description" Version 01.06
New document: "XT55 Hardware Interface Description" Version 02.06
Chapter
What is new
Throughout the
document
Deleted remarks regarding TCP/IP software which is currently not supported.
1.2
Updated list of related documents.
Preceding document: "XT55 Hardware Interface Description" Version 01.00b
New document: "XT55 Hardware Interface Description" Version 01.06
Chapter
What is new
1.4
Updated list of standards.
2.1, 4.2
SDn1, SDn2: both GPS interfaces support baud rates from 4800 … 115200 bps
3.6, 3.12.2
More detailed description of status LED patterns
3.11, 3.11.2
• Use GSM_CCGND line to shield GSM_CCIO line from GSM_CCCLK line.
• Connect a 47 pF capacitor from the GSM_CCIO to the GSM_CCGND line.
3.11.2
Improved Figure 20
4.2
GPS receiver sensitivity has been changed from –142 dBm to –138 dBm
4.7
GPS_RFPC0 and GPS_RFPC1 must be connected as shown in Figure 58 in order
to use the Trickle Power mode, deleted GPS_GPIO9 (T_MARK)
6.4
Added footnote regarding test conditions
6.5.3
Table 31: Sidetone gain at default settings for audio mode 5 and 6 set to -∞ dB
7.2
Figure 53: Improved figure
8.2
Added IC: 267W-XT55/56
Figure 58: Two pull-up resistors must be added in order to ensure the correct
voltage level during start-up and reset procedure of the GPS base-band
processor.Added 47 pF capacitor
10
Added new Siemens ordering numbers
Preceding document: "XT55 Hardware Interface Description" Version 01.00a
New document: "XT55 Hardware Interface Description" Version 01.00b
Chapter
What is new
General Notes
Added note about the use of extracts from SiRF documentation
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Preceding document: "XT55 Hardware Interface Description" Version 01.00
New document: "XT55 Hardware Interface Description" Version 01.00a
Chapter
What is new
General Notes
Added trademark notice regarding SiRF Software
7.1
Figure 51: Mechanical dimensions of XT55/56 – added new drawing
Preceding document: "XT55/56 Hardware Interface Description" Version 00.02
New document: "XT55/56 Hardware Interface Description" Version 01.00
Chapter
What is new
Throughout the
document
Renamed “GSM/GPRS part” to “GSM part”
2nd cover page
New version of General Notes
1.2
Updated list of related documents
1.4
XT55/56 is now fully type approved and marked with the CE conformity label
Restructured the chapter, moved figures regarding SiRF Demo, AVL and TCP/IP
application to Chapter 9
3.5.3
Added remark that charging begins again when voltage drops below 4.0V.
6.2
Added footnote regarding heat sink.
7.2
Added further mounting advices
New chapter: Design example
----
Deleted chapter: Maximum number of turn-on / turn-off cycles
Preceding document: "XT55/56 Hardware Interface Description" Version 00.01
New document: "XT55/56 Hardware Interface Description" Version 00.02
Chapter
What is new
Throughout this • Maximum temperature has been changed from +65°C to +70°C.
document
• Pins have been clearly divided into GPS and GSM pins.
1.2
Updated list of related documents
1.3
Added GPS terms abbreviations
2.1
Added new key features regarding GPS
2.2
Added Figure 56 and Figure 57
3.5.2
Deleted vendor XWODA, battery pack can be obtained from various dealers
4.1
New chapter: Theory of Operation
4.3f
Detailed description of GPS operating modes
4.4
Added information regarding the power supply pins of the GPS part
4.5
New chapter: General Purpose Input/Output
4.6
More information regarding the two serial interfaces of the GPS part
4.7
Added a complete list of GPS control signals
4.8
New chapter describing the functionality of the integrated GPS receiver
4.9
New chapter: Operation Procedure
4.10
Detailed description of GPS start-up procedure, coldstart, warmstart and hotstart
6.3
Renamed chapter and corrected pin assignment of B2B connector
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s
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Introduction
This document describes the hardware interface of the Siemens XT55/56 module that
connects to the cellular device application and the air interface. As XT55/56 is intended to
integrate with a wide range of application platforms, all functional components are described
in great detail.
This guide therefore covers all information needed to design and set up cellular applications
incorporating the XT55/56 module. It aids rapid retrieval of interface specifications, electrical
and mechanical details and information on the requirements to be considered for integration
of further components.
1.1
Supported Software and Hardware Releases
All XT55/56 02.96 documents refer to the software and hardware releases listed below.
GSM hardware / software:
XT55 Release 02.96, XT56 Release 02.96
GPS software:
Standard GPS Software Revision 2.3
GPS hardware:
Revision 5
The GPS hardware revision number is integrated in the 14-digit
product number printed on the product label. The 5th digit
represents the hardware revision.
Figure 1: Product label placed on XT55/56 module
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1.2
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15]
[16]
[17]
[18]
Related Documents
XT55 AT Command Set
XT56 AT Command Set
XT55/56 GPS Command Specification
XT55/56 Release Note
XT55 AVL Software User’s Guide
XT55/56 GPS Startup User's Guide
XT55/56 GSM/GPS Evaluation Board Description
GPRS Startup User's Guide
Remote-SAT User's Guide
DSB45 Support Box - Evaluation Kit for Siemens Cellular Engines
Application Note 14: Audio and Battery Parameter Download
Application Note 02: Audio Interface Design
Application Note 22: Using TTY / CTM equipment
Multiplexer User's Guide
Multiplex Driver Developer’s Guide for Windows 2000 and Windows XP
Multiplex Driver Installation Guide for Windows 2000 and Windows XP
Application Note 24: Application Developer’s Guide
Application Note 28: Customer SIM Lock
Application Note 21: Implementing Customer IMEI
Prior to using the XT55/56 engines or upgrading to a new firmware release, be sure to
carefully read the latest product information.
To visit the Siemens Website you can use the following link:
http://www.siemens.com/wm
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1.3
Terms and Abbreviations
Abbreviation
Description
AD
Analog / Digital
ADC
Analog-to-Digital Converter
AFC
Automatic Frequency Control
AGC
Automatic Gain Control
ANSI
American National Standards Institute
ARFCN
Absolute Radio Frequency Channel Number
ARP
Antenna Reference Point
ASC0 / ASC1
Asynchronous Controller. Abbreviations used for first and second serial interface of
XT55/56
ASIC
Application Specific Integrated Circuit
Thermistor Constant
B2B
Board-to-board connector
BER
Bit Error Rate
BTS
Base Transceiver Station
CB or CBM
Cell Broadcast Message
CE
Conformité Européene (European Conformity)
CHAP
Challenge Handshake Authentication Protocol
CPU
Central Processing Unit
CS
Coding Scheme
CSD
Circuit Switched Data
CTS
Clear to Send
DAC
Digital-to-Analog Converter
DAI
Digital Audio Interface
dBW
Decibel per Watt
dBm0
Digital level, 3.14dBm0 corresponds to full scale, see ITU G.711, A-law
DCE
Data Communication Equipment (typically modems, e.g. Siemens GSM engine)
DCS 1800
Digital Cellular System, also referred to as PCN
DGPS
Differential GPS
DOP
Dilution of Precision
DRX
Discontinuous Reception
DSB
Development Support Box
DSP
Digital Signal Processor
DSR
Data Set Ready
DTE
Data Terminal Equipment (typically computer, terminal, printer or, for example, GSM
application)
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Abbreviation
Description
DTR
Data Terminal Ready
DTX
Discontinuous Transmission
EFR
Enhanced Full Rate
EGSM
Enhanced GSM
EMC
Electromagnetic Compatibility
ESD
Electrostatic Discharge
ETS
European Telecommunication Standard
FCC
Federal Communications Commission (U.S.)
FDMA
Frequency Division Multiple Access
FR
Full Rate
GGA
GPS Fixed Data
GMSK
Gaussian Minimum Shift Keying
GPRS
General Packet Radio Service
GPS
Global Positioning System
GSM
Global Standard for Mobile Communications
HiZ
High Impedance
HR
Half Rate
I/O
Input/Output
IC
Integrated Circuit
IF
Intermediate Frequency
IMEI
International Mobile Equipment Identity
ISO
International Standards Organization
ITU
International Telecommunications Union
kbps
kbits per second
LED
Light Emitting Diode
Li-Ion
Lithium-Ion
LNA
Low Noise Amplifier
Mbps
Mbits per second
MMI
Man Machine Interface
MO
Mobile Originated
MS
Mobile Station (GSM engine), also referred to as TE
MSISDN
Mobile Station International ISDN number
MSK
Minimum Shift Key
MT
Mobile Terminated
NTC
Negative Temperature Coefficient
NMEA
National Maritime Electronics Association
OEM
Original Equipment Manufacturer
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Abbreviation
Description
PA
Power Amplifier
PAP
Password Authentication Protocol
PBCCH
Packet Switched Broadcast Control Channel
PCB
Printed Circuit Board
PCL
Power Control Level
PCM
Pulse Code Modulation
PCN
Personal Communications Network, also referred to as DCS 1800
PCS
Personal Communication System, also referred to as GSM 1900
PDU
Protocol Data Unit
PLL
Phase Locked Loop
PPP
Point-to-point protocol
PRN
Pseudo-Random Noise Number – The identity of GPS satellites
PSU
Power Supply Unit
R&TTE
Radio and Telecommunication Terminal Equipment
RAM
Random Access Memory
RF
Radio Frequency
RMS
Root Mean Square (value)
ROM
Read-only Memory
RP
Receive Protocol
RTC
Real Time Clock
RTCM
Radio Technical Commission for Maritime Services
Rx
Receive Direction
SA
Selective Availability
SAR
Specific Absorption Rate
SELV
Safety Extra Low Voltage
SIM
Subscriber Identification Module
SMS
Short Message Service
SPI
Service Provider Interface
SRAM
Static Random Access Memory
TA
Terminal adapter (e.g. GSM engine)
TDMA
Time Division Multiple Access
TE
Terminal Equipment, also referred to as DTE
Tx
Transmit Direction
UART
Universal asynchronous receiver-transmitter
URC
Unsolicited Result Code
USSD
Unstructured Supplementary Service Data
VSWR
Voltage Standing Wave Ratio
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Abbreviation
Description
WAAS
Wide Area Augmentation System
Phonebook abbreviations
FD
SIM fixdialing phonebook
LD
SIM last dialing phonebook (list of numbers most recently dialed)
MC
Mobile Equipment list of unanswered MT calls (missed calls)
ME
Mobile Equipment phonebook
ON
Own numbers (MSISDNs) stored on SIM or ME
RC
Mobile Equipment list of received calls
SM
SIM phonebook
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1.4
Type Approval
XT55/56 has been approved to comply with the directives and standards listed below and is
labeled with the CE conformity mark.
European directives
99/05/EC
“Directive of the European Parliament and of the council of 9 March
1999 on radio equipment and telecommunications terminal equipment
and the mutual recognition of their conformity”, in short referred to as
R&TTE Directive 1999/5/EC
89/336/EC
Directive on electromagnetic compatibility
73/23/EC
Directive on electrical equipment designed for use within certain
voltage limits (Low Voltage Directive)
2002/95/EC
Directive of the European Parliament and of the Council of 27
January 2003 on the restriction of the use of certain hazardous
substances in electrical and electronic equipment (RoHS)
2002/96/EC
Directive of the European Parliament and of the Council on waste
electrical and electronic equipment (WEEE)
2003/108/EC
Directive of the European Parliament and of the Council of 8
December 2003 amending directive 2002/96/ec on waste electrical
and electronic equipment (WEEE)
Standards of North American Type Approval
CFR Title 47
“Code of Federal Regulations, Part 15, Part 22 and Part 24
(Telecommunications, PCS)”; US Equipment Authorization FCC
NAPRD.03
“Overview of PCS Type certification review board
Mobile Equipment Type Certification and IMEI control”
PCS Type Certification Review board (PTCRB)
Standards of European Type Approval
3GPP TS 51.010-1
“Digital cellular telecommunications system (Phase 2); Mobile Station
(MS) conformance specification”.
ETSI EN 301 511
“V7.0.1 Standard
Candidate Harmonized European Standard (Telecommunications
series) Global System for Mobile communications (GSM); Harmonized
standard for mobile stations in the GSM 900 and DCS 1800 bands
covering essential requirements under article 3.2 of the R&TTE
directive (1999/5/EC) (GSM 13.11 version 7.0.1 Release 1998)”
GCF-CC
“Global Certification Forum - Certification Criteria” V3.18.0
ETSI EN 301 489-1
“V1.2.1 Candidate Harmonized European Standard (Telecommunications series) Electro Magnetic Compatibility and Radio
spectrum Matters (ERM); Electro Magnetic Compatibility (EMC) standard for radio equipment and services; Part 1: Common Technical
Requirements”
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ETSI EN 301 489-07
“V1.2.1 Electro Magnetic Compatibility and Radio spectrum Matters
(ERM); Electro Magnetic Compatibility (EMC) standard for radio
equipment and services; Part 7: Specific conditions for mobile and
portable radio and ancillary equipment of digital cellular radio telecommunications systems (GSM and DCS)”
EN 60 950
Safety of information technology equipment (2000)
Requirements of quality
IEC 60068
Environmental testing
DIN EN 60529
IP codes
SAR requirements specific to portable mobiles
Mobile phones, PDAs or other portable transmitters and receivers incorporating a GSM
module must be in accordance with the guidelines for human exposure to radio frequency
energy. This requires the Specific Absorption Rate (SAR) of portable XT55/56 based
applications to be evaluated and approved for compliance with national and/or international
regulations.
Since the SAR value varies significantly with the individual product design manufacturers are
advised to submit their product for approval if designed for portable use. For European and
US markets the relevant directives are mentioned below. It is the responsibility of the
manufacturer of the final product to verify whether or not further standards, recommendations
or directives are in force outside these areas.
Products intended for sale on US markets
ES 59005/ANSI C95.1 Considerations for evaluation of human exposure to Electromagnetic
Fields (EMFs) from Mobile Telecommunication Equipment (MTE) in
the frequency range 30MHz-6GHz
Products intended for sale on European markets
EN 50360
Product standard to demonstrate the compliance of mobile phones
with the basic restrictions related to human exposure to
electromagnetic fields (300MHz - 3GHz)
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1.5
Safety Precautions
The following safety precautions must be observed during all phases of the operation, usage,
service or repair of any cellular terminal or mobile incorporating XT55/56. Manufacturers of
the cellular terminal are advised to convey the following safety information to users and
operating personnel and to incorporate these guidelines into all manuals supplied with the
product. Failure to comply with these precautions violates safety standards of design,
manufacture and intended use of the product. Siemens AG assumes no liability for customer
failure to comply with these precautions.
When in a hospital or other health care facility, observe the restrictions on the
use of mobiles. Switch the cellular terminal or mobile off, if instructed to do so
by the guidelines posted in sensitive areas. Medical equipment may be
sensitive to RF energy.
The operation of cardiac pacemakers, other implanted medical equipment
and hearing aids can be affected by interference from cellular terminals or
mobiles placed close to the device. If in doubt about potential danger, contact
the physician or the manufacturer of the device to verify that the equipment is
properly shielded. Pacemaker patients are advised to keep their hand-held
mobile away from the pacemaker, while it is on.
Switch off the cellular terminal or mobile before boarding an aircraft. Make
sure it cannot be switched on inadvertently. The operation of wireless
appliances in an aircraft is forbidden to prevent interference with
communications systems. Failure to observe these instructions may lead to
the suspension or denial of cellular services to the offender, legal action, or
both.
Do not operate the cellular terminal or mobile in the presence of flammable
gases or fumes. Switch off the cellular terminal when you are near petrol
stations, fuel depots, chemical plants or where blasting operations are in
progress. Operation of any electrical equipment in potentially explosive
atmospheres can constitute a safety hazard.
Your cellular terminal or mobile receives and transmits radio frequency
energy while switched on. Remember that interference can occur if it is used
close to TV sets, radios, computers or inadequately shielded equipment.
Follow any special regulations and always switch off the cellular terminal or
mobile wherever forbidden, or when you suspect that it may cause
interference or danger.
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Road safety comes first! Do not use a hand-held cellular terminal or mobile
when driving a vehicle, unless it is securely mounted in a holder for handsfree
operation. Before making a call with a hand-held terminal or mobile, park the
vehicle.
Handsfree devices must be installed by qualified personnel. Faulty installation
or operation can constitute a safety hazard.
SOS
IMPORTANT!
Cellular terminals or mobiles operate using radio signals and cellular
networks. Because of this connection cannot be guaranteed at all times under
all conditions. Therefore, you should never rely solely upon any wireless
device for essential communications, for example emergency calls.
Remember, in order to make or receive calls, the cellular terminal or mobile
must be switched on and in a service area with adequate cellular signal
strength.
Some networks do not allow for emergency calls if certain network services or
phone features are in use (e.g. lock functions, fixed dialing etc.). You may
need to deactivate those features before you can make an emergency call.
Some networks require that a valid SIM card be properly inserted in the
cellular terminal or mobile.
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Product Concept
Designed for use on any GSM network in the world, Siemens XT55 is a tri-band GSM/GPRS
engine that works on the three frequencies GSM 900 MHz, GSM 1800 MHz and GSM
1900 MHz and supports also GPS technology for satellite navigation. XT56 is a tri-band
GSM/GPRS engine that works on the three frequencies GSM 850MHz, GSM 1800 MHz and
GSM 1900 MHz and supports also GPS technology for satellite navigation. XT55/56 features
GPRS multislot class 10 and supports the GPRS coding schemes CS-1, CS-2, CS-3 and
CS-4.
The compact design of the XT55/56 module makes it easy to integrate GSM / GPRS and
GPS as an all-in-one solution. It saves significantly both time and cost for integration of
additional hardware components.
The integrated GPS module provides instant location information using satellite signals to
enable users to ascertain where they are anywhere in the world. It consists of a fully
integrated RF receiver and a 12 channel baseband.
The tiny XT55/56 module incorporates all you need to create high-performance GSM/GPRS
solutions: baseband processor, power supply ASIC, complete radio frequency circuit
including a power amplifier and antenna interface. The power amplifier is directly fed from the
supply voltage GSM_BATT+. A compact “stacked FLASH / SRAM” device stores the
XT55/56 software in the flash memory section, and static RAM section provides the
additional storage capacity required by GPRS connectivity.
The physical interface to the cellular application is made through a board-to-board connector.
It consists of 80 pins, required for controlling the unit, receiving GPS location data,
transferring data and audio signals and providing power supply lines.
XT55/56 comprises two serial GSM interfaces (ASC0 and ASC1) and two serial GPS
interfaces (Serial data 1 and Serial data 2) giving you maximum flexibility for easy integration
with the Man-Machine Interface (MMI).
An extremely versatile audio concept offers various audio interfaces, each available on the
board-to-board connector: a digital audio interface (DAI) and two analog audio interfaces.
Using AT commands you can easily switch back and forth and select different audio modes.
The external dual-band or triple-band GSM antenna can be connected optionally to a
connector on the top side or to a pad on the bottom side. A separate GPS antenna must be
connected to the GPS part of the module in order to properly receive satellite data.
For battery powered applications, XT55/56 features a charging control which can be used to
charge a Li-Ion battery. The charging circuit must be implemented outside the module on the
application platform.
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2.1
XT55/56 Key Features at a Glance
Table 1: XT55/56 key features
Feature
Implementation
Power supply
Supply voltage 3.3V – 4.8V for the GSM / GPRS module
Separate power supply source: 3.3V ± 5% for the GPS device
Power saving (GSM)
Minimizes power consumption in SLEEP mode
Power saving (GPS)
Trickle Power™ / Push-to-Fix mode
Charging
Supports charging control for Li-Ion battery for the GSM part of the module
Frequency bands
• XT55 Tri-band: EGSM 900, GSM 1800, GSM 1900
• XT56 Tri-band: GSM 850, GSM 1800, GSM 1900
• Compliant to GSM Phase 2/2+
GSM class
Small MS
Transmit power
• Class 4 (2W) at EGSM 900 and GSM 850
• Class 1 (1W) at GSM 1800 and GSM 1900
GPRS connectivity
• GPRS multi-slot class 10
• GPRS mobile station class B
• GPS receiver with SiRFstar Ile/LP chip set
GPS features
• Processor type ARM7/TDMI
• Sirf GSW2, version 2.3
Temperature range:
• Normal operation:
• Restricted operation:
Temperature control
and auto switch-off
DATA
-20°C to +55°C
-25°C to -20°C and +55°C to +70°C
• Constant temperature control prevents damage to XT55/56 when the
specified temperature is exceeded. When an emergency call is in
progress the automatic temperature shutdown functionality is
deactivated.
GPRS: • GPRS data downlink transfer: max. 85.6 kbps (see Table 2)
• GPRS data uplink transfer: max. 42.8 kbps (see Table 2
• Coding scheme: CS-1, CS-2, CS-3 and CS-4
• XT55/56 supports the two protocols PAP (Password Authentication
Protocol) and CHAP (Challenge Handshake Authentication Protocol)
commonly used for PPP connections.
• Support of Packet Switched Broadcast Control Channel (PBCCH) allows
you to benefit from enhanced GPRS performance when offered by the
network operators.
CSD:
• CSD transmission rates: 2.4, 4.8, 9.6, 14.4 kbps, non-transparent, V.110
• Unstructured
WAP:
SMS
Supplementary
Services
Data
(USSD)
support
WAP compliant
• MT, MO, CB, Text and PDU mode
• SMS storage: SIM card plus 25 SMS locations in the mobile equipment
• Transmission of SMS alternatively over CSD or GPRS. Preferred mode
can be user-defined.
MMS
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Feature
Implementation
FAX
Group 3: Class 1, Class 2
SIM interface
Supported SIM card: 3V
External SIM card reader has to be connected via interface connector (note
that card reader is not part of XT55/56)
External antenna
GSM / GPRS:
GPS:
Connected via 50 Ohm antenna connector or antenna pad.
Separate GPS antenna connector. See Figure 49 for details.
Audio interfaces
Two analog audio interfaces, one digital audio interface (DAI)
Audio features
Speech codec modes:
• Half Rate (ETS 06.20)
• Full Rate (ETS 06.10)
• Enhanced Full Rate (ETS 06.50 / 06.60 / 06.80)
• Adaptive Multi Rate (AMR)
Handsfree operation
• Echo cancellation
• Noise reduction
Two serial GSM
interfaces:
ASC0, ASC1
• 2.65V level, bi-directional bus for AT commands and data
• ASC0 – full-featured 8-wire serial interface. Supports RTS0/CTS0
hardware handshake and software XON/XOFF flow control. Multiplex
ability according to GSM 07.10 Multiplexer Protocol.
• ASC1 - 4-wire serial interface. Supports RTS1/CTS1 hardware
handshake and software XON/XOFF flow control.
• Baud rate: 300bps ... 230kbps on ASC0 and ASC1
• Autobauding (on ASC0 only) detects 1200, 2400, 4800, 9600, 19200,
38400, 57600, 115200, 230400 bps
• Baud rate: 4800 … 115200 bps on SD1 and SD2 (default setting on both
Two serial GPS
interfaces: 9600 bps)
interfaces: SDn1, SDn2
Phonebook
management
Supported phonebook types: SM, FD, LD, MC, RC, ON, ME
SIM Application Toolkit
Supports SAT class 3, GSM 11.14 Release 98, support of letter class “c”
Ringing tones
Offers a choice of 7 different ringing tones / melodies, easily selectable with
AT command
Real time clock
Implemented
Timer function
Programmable via AT command
Support of TTY/CTM
To benefit from TTY communication via GSM, CTM equipment can be
connected to one of the three audio interfaces.
Physical characteristics Size:
Weight:
35.0 ± 0.15mm x 53.0 ± 0.15mm x 5.1 ± 0.15mm
11g
RoHS, WEEE
All hardware components are fully compliant with the EU RoHS and WEEE
Directives
Firmware upgrade
XT55/56 firmware upgradable over serial interface
Evaluation kit
The DSB45 Support Box is an evaluation kit designed to test and type
approve the GSM part of Siemens cellular engines and provide a sample
configuration for application engineering. See Chapter 10 for details.
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Table 2: GSM coding schemes and maximum net data rates over air interface
Coding scheme
1 Timeslot
2 Timeslots
4 Timeslots
CS-1:
9.05 kbps
18.1 kbps
36.2 kbps
CS-2:
13.4 kbps
26.8 kbps
53.6 kbps
CS-3:
15.6 kbps
31.2 kbps
62.4 kbps
CS-4:
21.4 kbps
42.8 kbps
85.6 kbps
Please note that the values stated above are maximum ratings which, in practice, are influenced by a
great variety of factors, primarily, for example, traffic variations and network coverage.
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2.2
Circuit Concept
The XT55/56 module comprises the following major functional components:
GSM / GPRS baseband block:
• Baseband controller operating at 26MHz
• Power supply ASIC
• Stacked Flash / SRAM
• Application interface (board-to-board connector)
GSM RF block:
• RF transceiver
• RF power amplifier / FEM
• Antenna connector
GPS block:
• Processor type: ARM7/TDMI
• Processor speed: depending on GPS software, e.g. 12.277MHz for the standard GPS
software supplied by Siemens
GPS RF block:
• GPS receiver with SiRFstar Ile/LP chip set
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Active GPS antenna
GSM antenna
GSM
–
GSM
module
XT55
XT56
GPS –
Modul
GPS module
Modul
GSM_RXD0
ASC0
GSM_TXD0
6 Modem
Status lines
ASC1
Serial data 2 Serial data 1
GSM_RXD1
GSM_TXD1
GSM_RTS1
GSM_CTS1
SDO2
SDI2
SDI1
SDO1
80 pin B2B
80 pin B2B
Customer application
Serial 1
GSM
Serial 0
GSM
Serial 2 Serial 1
GPS
GPS
Figure 2: Block diagram of serial interface concept
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GSM Application Interface
The GSM part of the XT55/56 module incorporates several sub-interfaces described in the
following chapters:
• Power supply and charging control (see Chapters 3.2 and 3.3)
• Dual serial GSM interface (see Chapter 3.9)
• Two analog audio interfaces and a digital audio interface (see Chapter 3.10)
• SIM interface (see Chapter 3.11)
Electrical and mechanical characteristics of the board-to-board connector are specified in
Chapter 7.3. Ordering information for mating connectors and cables are included.
3.1
GSM/GPRS Operating Modes
The table below briefly summarizes the various operating modes referred to in the following
chapters. All information regarding GPS/GPRS operating modes are available in Chapter
4.3.
Table 3: Overview of GSM/GPRS operating modes
Mode
Function
Normal operation
GSM / GPRS SLEEP
Various powersave
command.
modes
set
with
AT+CFUN
Software is active to minimum extent. If the module was
registered to the GSM network in IDLE mode, it is
registered and paging with the BTS in SLEEP mode,
too. Power saving can be chosen at different levels:
The NON-CYCLIC SLEEP mode (AT+CFUN=0)
disables the AT interface. The CYCLIC SLEEP modes
AT+CFUN=5, 6, 7, 8 and 9 alternatively activate and
deactivate the AT interfaces to allow permanent access
to all AT commands.
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GSM IDLE
Software is active. Once registered to the GSM
network, paging with BTS is carried out. The module is
ready to send and receive.
GSM TALK
Connection between two subscribers is in progress.
Power consumption depends on network coverage
individual settings, such as DTX off/on, FR/EFR/HR,
hopping sequences, antenna.
GPRS IDLE
Module is ready for GPRS data transfer, but no data is
currently sent or received. Power consumption depends
on network settings and GPRS configuration (e.g.
multislot settings).
GPRS DATA
GPRS data transfer in progress. Power consumption
depends on network settings (e.g. power control level),
uplink / downlink data rates and GPRS configuration
(e.g. used multislot settings).
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Mode
Function
POWER DOWN
Normal shutdown after sending the AT^SMSO command.
The Power Supply ASIC (PSU-ASIC) disconnects the supply voltage from the
baseband part of the circuit. Only a voltage regulator in the PSU-ASIC is active
for powering the RTC. Software is not active. The serial interfaces are not
accessible.
Operating voltage (connected to GSM_BATT+) remains applied.
Alarm mode
Restricted operation launched by RTC alert function while the module is in
POWER DOWN mode. Module will not be registered to GSM network. Limited
number of AT commands is accessible.
Charge-only mode Limited operation for battery powered applications. Enables charging while
module is detached from GSM network. Limited number of AT commands is
accessible. There are several ways to launch Charge-only mode:
• From POWER DOWN mode: Connect charger to the charger input pin of the
external charging circuit and the module’s GSM_POWER pin when XT55/56
was powered down by AT^SMSO.
• From Normal mode: Connect charger to the charger input pin of the external
charging circuit and the module’s GSM_POWER pin, then enter AT^SMSO.
Charge mode
during normal
operation
Normal operation (SLEEP, IDLE, TALK, GPRS IDLE, GPRS DATA) and
charging running in parallel. Charge mode changes to Charge-only mode when
the module is powered down before charging has been completed.
See Table 11 and Table 12 for the various options of waking up the GSM part of the XT55/56 module
and proceeding from one mode to another.
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3.2
Power Supply
The power supply for the GSM part of the XT55/56 module has to be a single voltage source
of VGSM_BATT+= 3.3V...4.8V. It must be able to provide sufficient current in a transmit burst
which typically rises to 1.6A.
All the key functions for supplying power to the device are handled by an ASIC power supply.
The ASIC provides the following features:
• Stabilizes the supply voltages for the GSM baseband using low drop linear voltage
regulators.
• Controls the module's power up and power down procedures.
A watchdog logic implemented in the baseband processor periodically sends signals to
the ASIC, allowing it to maintain the supply voltage for all digital XT55/56 components.
Whenever the watchdog pulses fail to arrive constantly, the module is turned off.
• Delivers, across the GSM_VDD pin, a regulated voltage of 2.9V. The output voltage
GSM_VDD may be used to supply, for example, an external LED or a level shifter.
However, the external circuitry must not cause any spikes or glitches on voltage
GSM_VDD. This voltage is not available in POWER DOWN mode. Therefore, the
GSM_VDD pin can be used to indicate whether or not GSM part of the XT55/56 module
is in POWER DOWN mode.
• Provides power to the SIM interface.
The RF power amplifier is driven directly from GSM_BATT+.
3.2.1
Power Supply Pins on the Board-to-Board Connector
Five GSM_BATT+ pins of the board-to-board connector are dedicated to connect the supply
voltage, five GND pins are recommended for grounding. The values stated below must be
measured directly at the reference points on the XT55/56 board (TP GSM_BATT+ and TP
GND illustrated in Figure 50).
The GSM_POWER and GSM_CHARGE pins serve as control signals for charging a Li-Ion
battery. GSM_VDDLP can be used to back up the RTC.
Table 4: Power supply pins of board-to-board connector
Signal name
I/O
Description
Parameter
GSM_BATT+
I/O
Positive operating voltage
3.3 V...4.8 V, Ityp ≤ 1.6 A during transmit burst
Reference points are the
test points
The minimum operating voltage must not fall
below 3.3 V, not even in case of voltage
drop.
0V
GND
Ground
GSM_POWER
This line signals to the
processor that the
charger is connected.
GSM_CHARGE
Control signal for external
charging transistor
GSM_VDDLP
I/O
Can be used to back up
the RTC when VGSM_BATT+
is not applied.
See Chapter 3.8
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UOUT,max < VGSM_BATT+
UIN = 2.0 V...5.5 V
Ri = 1kΩ
Iin,max = 30µA
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3.2.2
Minimizing Power Losses
When designing the power supply for your application please pay specific attention to power
losses. Ensure that the input voltage VGSM_BATT+ never drops below 3.3V on the GSM part of
the XT55/56 board, not even in a transmit burst where current consumption can rise to
typical peaks of 1.6A. It should be noted that the GSM part of the XT55/56 module switches
off when exceeding these limits. Any voltage drops that may occur in a transmit burst should
not exceed 400mV. For further details see Chapter 6.4.
The best approach to reducing voltage drops is to use a board-to-board connection as
recommended, and a low impedance power source. The resistance of the power supply lines
on the host board and of a battery pack should also be considered.
Note:
If the application design requires an adapter cable between both board-to-board
connectors, use a cable as short as possible in order to minimize power losses.
Example: If the length of the cable reaches the maximum length of 200mm, this connection
may cause, for example, a resistance of 50mΩ in the GSM_BATT+ line and
50mΩ in the GND line. As a result, a 1.6A transmit burst would add up to a total
voltage drop of 160mV. Plus, if a battery pack is involved, further losses may
occur due to the resistance across the battery lines and the internal resistance of
the battery including its protective circuit.
Transmit
burst 1.6A
Transmit
burst 1.6A
GSM_BATT+
Ripple
Drop
min. 3.3V
Figure 3: Power supply limits during transmit burst
The input voltage VGSM_BATT+ must be measured directly at the test points on the XT55/56
board (TP GSM_BATT+ and TP GND illustrated in Figure 50).
3.2.3
Monitoring Power Supply
To help you monitor the supply voltage you can use the AT^SBV command which returns the
voltage measured at TP GSM_BATT+ and GND.
The voltage is continuously measured at intervals depending on the operating mode on the
RF interface. The duration of measuring ranges from 0.5s in TALK/DATA mode up to 50s
when the GSM part of the XT55/56 is in IDLE mode or Limited Service (deregistered). The
displayed voltage (in mV) is averaged over the last measuring period before the AT^SBV
command was executed.
For details please refer to [1].
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3.3
Power Up / Down Scenarios
In general, be sure not to turn on GSM part of the XT55/56 module while it is out of the
operating range of voltage and temperature stated in Chapters 6.2 and 6.3. The GSM part of
the XT55/56 would immediately switch off after having started and detected these
inappropriate conditions.
3.3.1
Turn on the GSM Part of XT55/56
The GSM part of the XT55/56 can be activated in a variety of ways, which are described in
the following chapters:
• via ignition line GSM_IGT: starts normal operating state (see Chapters 3.3.1.1 and
3.3.1.2)
• via GSM_POWER line: starts charging algorithm (see Chapters 3.5.4 and 3.3.1.3)
• via RTC interrupt: starts Alarm mode (see Chapter 3.3.1.4)
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3.3.1.1
Turn on the GSM Part of XT55/56 Using the Ignition Line GSM_IGT
(Power on)
To switch on the XT55/56 GSM part the GSM_IGT (Ignition) signal needs to be driven to
ground level for at least 100ms and not earlier than 10ms after the last falling edge of
GSM_VDD. This can be accomplished using an open drain/collector driver in order to avoid
current flowing into this pin.
GSM_BATT+
min. 10ms
HiZ
min.
100ms
HiZ
GSM_IGT
ca. 60ms
GSM_VDD
GSM_TXD0
GSM_TXD1
GSM_DSR0
GSM_EMERGOFF
Serial interfaces
ASC0 and ASC1
Software
controlled
Undefined
ca. 300ms
Inactive
Active
ca. 900ms
For details please see Chapter 3.3.1.2
Figure 4: Power-on by ignition signal
In a battery operated XT55/56 application, the duration of the GSM_IGT signal must be 1s
minimum when the charger is connected and you may want to go from Charge only mode to
Normal mode.
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Assertion of GSM_CTS indicates that the module is ready to receive data from the host
application. In addition, if configured to a fixed bit rate (AT+IPR≠0), the module will send the
URC “^SYSSTART” which notifies the host application that the first AT command can be sent
to the module. The duration until this URC is output varies with the SIM card and may take a
couple of seconds, particularly if the request for the SIM PIN is deactivated on the SIM card.
Please note that no “^SYSSTART” URC will be generated if autobauding (AT+IPR=0) is
enabled.
To allow the application to detect the ready state of the module we recommend using
hardware flow control which can be set with AT\Q or AT+ICF (see [1] for details). The default
setting of XT55/56 is AT\Q0 (no flow control) which shall be altered to AT\Q3 (RTS/CTS
handshake). If the application design does not integrate RTS/CTS lines the host application
shall wait at least for the “^SYSSTART” URC. However, if the URCs are neither used (due to
autobauding) then the only way of checking the module’s ready state is polling. To do so, try
to send characters (e.g. “at”) until the module is responding.
3.3.1.2
Timing of the Ignition Process
When designing your application platform take into account that powering up the GSM part of
the XT55/56 module requires the following steps.
• The ignition line cannot be operated until VGSM_BATT+ passes the level of 3.0V.
• The ignition line shall not be operated earlier than 10ms after the last falling edge of
GSM_VDD.
• 10ms after VGSM_BATT+ has reached 3.0V the ignition line can be switched low. The
duration of the falling edge must not exceed 1ms.
• Another 100ms are required to power up the module.
• Ensure that VGSM_BATT+ does not fall below 3.0V while the ignition line is driven. Otherwise
the module cannot be activated.
• If the GSM_VDDLP line is fed from an external power supply as explained in Chapter 3.8,
the GSM_IGT line is HiZ before the rising edge of GSM_BATT+.
3.0V
GSM_BATT+
0V
HiZ
HiZ
GSM_IGT
10ms
min. 100ms
max. 1ms
Figure 5: Timing of power-on process if GSM_VDDLP is not used
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3.0V
GSM_BATT+
0V
GSM_IGT
HiZ
HiZ
10ms
min. 100ms
max. 1ms
Figure 6: Timing of power-on process if GSM_VDDLP is fed from external source
3.3.1.3
Turn on the GSM Part of XT55/56 Using the GSM_POWER Signal
As detailed in Chapter 3.5.4, the charging adapter can be connected regardless of the
module’s operating mode (except for Alarm mode).
If the charger is connected to the charger input of the external charging circuit and the
module’s GSM_POWER pin while XT55/56 is off, processor controlled fast charging starts
(see Chapter 3.5.3). The GSM part of XT55/56 enters a restricted mode, referred to as
Charge-only mode where only the charging algorithm will be launched.
During the Charge-only mode XT55/56 is neither logged on to the GSM network nor are the
serial interfaces fully accessible. To switch to normal operation and log on to the GSM
network, the GSM_IGT line needs to be activated.
3.3.1.4
Turn on the GSM Part of XT55/56 Using the RTC (Alarm Mode)
Another power-on approach is to use the RTC, which is constantly supplied with power from
a separate voltage regulator in the power supply ASIC. The RTC provides an alert function,
which allows the GSM part of the XT55/56 to wake up whilst the internal voltage regulators
are off. To prevent the engine from unintentionally logging into the GSM network, this
procedure only enables restricted operation, referred to as Alarm mode. It must not be
confused with a wake-up or alarm call that can be activated by using the same AT command,
but without switching off power.
Use the AT+CALA command to set the alarm time. The RTC retains the alarm time if the
GSM part of XT55/56 was powered down by AT^SMSO. Once the alarm is timed out and
executed, XT55/56 enters the Alarm mode. This is indicated by an Unsolicited Result Code
(URC) which reads:
^SYSSTART ALARM MODE
Note that this URC is the only indication of the Alarm mode and will not appear when
autobauding was activated (due to the missing synchronization between DTE and DCE upon
start-up). Therefore, it is recommended to select a fixed baudrate before using the Alarm
mode. In Alarm mode only a limited number of AT commands is available. For further
instructions refer to the AT Command Set.
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Table 5: AT commands available in Alarm mode
AT command
Function
AT+CALA
Set alarm time
AT+CCLK
Set date and time of RTC
AT^SBC
In Alarm mode, you can only query the present current consumption and check
whether or not a charger is connected. The battery capacity is returned as 0,
regardless of the actual voltage (since the values measured directly on the cell are
not delivered to the module).
AT^SCTM
Query temperature range, enable/disable URCs to report critical temperature
ranges
AT^SMSO
Power down GSM engine
For the GSM engine to change from the Alarm mode to full operation (normal operating
mode) it is necessary to drive the ignition line to ground. This must be implemented in your
host application as described in Chapter 3.3.1.1.
If the charger is connected to the GSM_POWER line when GSM part of the XT55/56 is in
ALARM mode charging will start, while XT55/56 stays in ALARM mode. See also Chapter 3.7
which summarizes the various options of changing the mode of operation.
If your host application uses the GSM_SYNC pin to control a status LED as described in
Chapter 3.12.2.2, please note that the LED is off while the GSM engine is in Alarm mode.
3.3.2
Turn off the GSM Part of XT55/56
To switch the module off the following procedures may be used:
•
•
•
Normal shutdown procedure: Software controlled by sending the AT^SMSO command
over the serial application interface. See Chapter 3.3.2.1.
Emergency shutdown: Hardware driven by switching the GSM_EMERGOFF line of the
board-to-board-connector to ground = immediate shutdown of supply voltages, only
applicable if the software controlled procedure fails! See Chapter 3.3.2.2.
Automatic shutdown: See Chapter 3.3.3
a) Takes effect if undervoltage is detected.
b) Takes effect if XT55/56 board temperature exceeds critical limit.
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3.3.2.1
Turn off GSM Part of the XT55/56 Module Using AT^SMSO
The best and safest approach to powering down the XT55/56 GSM part is to issue the
AT^SMSO command. This procedure lets the GSM engine log off from the network and
allows the software to enter into a secure state and safe data before disconnecting the power
supply. The mode is referred to as POWER DOWN mode. In this mode, only the RTC stays
active.
Before switching off the device sends the following response:
^SMSO: MS OFF
OK
^SHUTDOWN
After sending AT^SMSO do not enter any other AT commands. There are two ways to verify
when the module turns off:
• Wait for the URC “^SHUTDOWN”. It indicates that data have been stored non-volatile
and the module turns off in less than 1 second.
• Also, you can monitor the GSM_VDD pin. The low state of GSM_VDD definitely indicates
that the module is switched off.
Be sure not to disconnect the operating voltage VGSM_BATT+ before the URC “^SHUTDOWN”
has been issued and the GSM_VDD signal has gone low. Otherwise you run the risk of
losing data.
While the GSM engine is in POWER DOWN mode the application interface is switched off
and must not be fed from any other source. Therefore, your application must be designed to
avoid any current flow into any digital pins of the application interface.
Note: In POWER DOWN mode, the GSM_EMERGOFF pin, the output pins of the ASC0
interface GSM_RXD0, GSM_CTS0, GSM_DCD0, GSM_DSR0, GSM_RING0 and the
output pins of the ASC1 interface GSM_RXD1 and GSM_CTS1 are switched to high
impedance state.
If this causes the associated input pins of your application to float, you are advised to
integrate an additional resistor (100 kΩ – 1 MΩ) at each line. In the case of the
GSM_EMERGOFF pin use a pull-down resistor tied to GND. In the case of the serial
interface pins you can either connect pull-up resistors to the GSM_VDD line, or pulldown resistors to GND.
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3.3.2.2
Caution:
Emergency Shutdown Using GSM_EMERGOFF Pin
Use the GSM_EMERGOFF pin only when, due to serious problems, the
software is not responding for more than 5 seconds. Pulling the
GSM_EMERGOFF pin causes the loss of all information stored in the volatile
memory since power is cut off immediately. Therefore, this procedure is
intended only for use in case of emergency, e.g. if XT55/56 fails to shut down
properly.
The GSM_EMERGOFF signal is available on the board-to-board connector. To control the
GSM_EMERGOFF line it is recommended to use an open drain / collector driver. To turn the
GSM engine off, the GSM_EMERGOFF line has to be driven to ground for ≥ 3.2s.
How does it work:
• Voltage
VGSM_BATT+
is
permanently
applied
to
the
GSM_BATT+
module.
• The module is active while
GSM_IGT
the internal reset signal is
kept at high level.
During operation of XT55
GSM_VDD
the baseband controller
generates watchdog pulses
Internal reset
at regular intervals.
max. 3.2s
Once the GSM_EMERGOFF
pin is grounded these
watchdog pulses are cut off
from the power supply ASIC.
The power supply ASIC
GSM_EMERGOFF
shuts down the internal
supply voltages of XT55
Controlled by
after max. 3.2s and the
Controlled by external
XT55/56 software
application
module
turns
off.
Consequently, the output
voltage at GSM_VDD is
switched off.
Figure 7: Deactivating GSM engine by GSM_EMERGOFF signal
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3.3.3
Automatic Shutdown
Automatic shutdown takes effect if
• the XT55/56 board is exceeding the critical limits of overtemperature or undertemperature
• the battery is exceeding the critical limits of overtemperature or undertemperature
• undervoltage is detected
The automatic shutdown procedure is equivalent to the power-down initiated with the
AT^SMSO command, i.e. XT55/56 logs off from the network and the software enters a
secure state avoiding loss of data. NOTE: This does not apply if overvoltage conditions or
unrecoverable hardware or software errors occur (see below for details).
Alert messages transmitted before the device switches off are implemented as Unsolicited
Result Codes (URCs). The presentation of these URCs can be enabled or disabled with the
two AT commands AT^SBC and AT^SCTM. The URC presentation mode varies with the
condition, please see Chapters 3.3.3.1 to 3.3.3.4 for details. For further instructions on AT
commands refer to [1].
3.3.3.1
Temperature Dependent Shutdown
The board temperature is constantly monitored by an internal NTC resistor located on the
PCB. The NTC that detects the battery temperature must be part of the battery pack circuit
as described in Chapter 3.5. The values detected by either NTC resistor are measured
directly on the board or the battery and therefore, are not fully identical with the ambient
temperature.
Each time the board or battery temperature goes out of range or back to normal, XT55/56
instantly displays an alert (if enabled).
• URCs indicating the level "1" or "-1" allow the user to take appropriate precautions, such
as protecting the module from exposure to extreme conditions. The presentation of the
URCs depends on the settings selected with the AT^SCTM write command:
AT^SCTM=1: Presentation of URCs is always enabled.
AT^SCTM=0 (default): Presentation of URCs is enabled for 15 seconds time after
start-up of XT55/56. After 15 seconds operation, the presentation will be disabled, i.e.
no alert messages can be generated.
• URCs indicating the level "2" or "-2" are instantly followed by an orderly shutdown. The
presentation of these URCs is always enabled, i.e. they will be output even though the
factory setting AT^SCTM=0 was never changed.
The maximum temperature ratings are stated in Table 26. Refer to Table 6 for the associated
URCs. All statements are based on test conditions according to IEC 60068-2-2 (still air).
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Table 6: Temperature dependent behavior
Sending temperature alert (15 s after start-up, otherwise only if URC presentation enabled)
^SCTM_A: 1
Caution: Tamb of battery close to over temperature limit.
^SCTM_B: 1
Caution: Tamb of board close to over temperature limit.
^SCTM_A: -1
Caution: Tamb of battery close to under temperature limit.
^SCTM_B: -1
Caution: Tamb of board close to under temperature limit.
^SCTM_A: 0
Battery back to uncritical temperature range.
^SCTM_B: 0
Board back to uncritical temperature range.
Automatic shutdown (URC appears no matter whether or not presentation was enabled)
^SCTM_A: 2
Alert: Tamb of battery equal or beyond over temperature limit. XT55/56 switches off.
^SCTM_B: 2
Alert: Tamb of board equal or beyond over temperature limit. XT55/56 switches off.
^SCTM_A: -2
Alert: Tamb of battery equal or below under temperature limit. XT55/56 switches off.
^SCTM_B: -2
Alert: Tamb of board equal or below under temperature limit. XT55/56 switches off.
3.3.3.2
Temperature Control during Emergency Call
If the temperature limit is exceeded while an emergency call is in progress the engine
continues to measure the temperature, but deactivates the shutdown functionality. If the
temperature is still out of range when the call ends, the module switches off immediately
(without another alert message).
3.3.3.3
Undervoltage Shutdown if Battery NTC is Present
In applications where the module’s charging technique is used and an NTC is connected to
the GSM_BATT_TEMP terminal, the software constantly monitors the applied voltage. If the
measured battery voltage is no more sufficient to set up a call the following URC will be
presented:
^SBC: Undervoltage.
The message will be reported, for example, when you attempt to make a call while the
voltage is close to the critical limit and further power loss is caused during the transmit burst.
To remind you that the battery needs to be charged soon, the URC appears several times
before the module switches off.
To enable or disable the URC use the AT^SBC command. The URC will be enabled when
you enter the write command and specify the power consumption of your GSM application.
Step by step instructions are provided in [1].
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3.3.3.4
Undervoltage Shutdown if no Battery NTC is Present
The undervoltage protection is also effective in applications, where no NTC connects to the
GSM_BATT_TEMP terminal. Thus, you can take advantage of this feature even though the
application handles the charging process or XT55/56 is fed by a fixed supply voltage. All you
need to do is executing the write command AT^SBC= which automatically enables
the presentation of URCs. You do not need to specify .
Whenever the supply voltage falls below the specified value (see Table 28) the URC
^SBC: Undervoltage
appears several times before the module switches off.
3.3.3.5
Overvoltage Shutdown
For overvoltage conditions, no software controlled shutdown is implemented. If the supply
voltage exceeds the maximum value specified in Table 28, loss of data and even
unrecoverable hardware damage can occur.
Keep in mind that several XT55/56 components are directly linked to GSM_BATT+ and,
therefore, the supply voltage remains applied at major parts of XT55/56. Especially the
power amplifier is very sensitive to high voltage and might even be destroyed.
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3.4
Automatic GPRS Multislot Class Change
Temperature control is also effective for operation in GPRS Multislot Class 10. If the board
temperature increases to the limit specified for restricted operation1) while data are
transmitted over GPRS, the module automatically reverts from GPRS Multislot Class 10 (2
Tx) to Class 8 (1Tx). This reduces the power consumption and, consequently, causes the
board’s temperature to decrease. Once the temperature drops to a value of 5 degrees below
the limit of restricted operation, XT55/56 returns to the higher Multislot Class. If the
temperature stays at the critical level or even continues to rise, XT55/56 will not switch back
to the higher class.
After a transition from Multislot Class 10 to Multislot 8 a possible switchback to Multislot
Class 10 is blocked for one minute.
Please note that there is not one single cause of switching over to a lower GPRS Multislot
Class. Rather it is the result of an interaction of several factors, such as the board
temperature that depends largely on the ambient temperature, the operating mode and the
transmit power. Furthermore, take into account that there is a delay until the network
proceeds to a lower or, accordingly, higher Multislot Class. The delay time is network
dependent. In extreme cases, if it takes too much time for the network and the temperature
cannot drop due to this delay, the module may even switch off as described in Chapter
3.3.3.1.
1)
See Table 26 for temperature limits known as restricted operation.
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3.5
Charging Control of the GSM Part
The GSM part of the XT55/56 module integrates a charging management for Li-Ion batteries.
You can skip this chapter if charging is not your concern, or if you are not using the
implemented charging algorithm.
XT55/56 has no on-board charging circuit. To benefit from the implemented charging
management you are required to install a charging circuit within your application. In this case,
XT55/56 needs to be powered from a Li-Ion battery pack, e.g. as specified in Table 8.
Note:
The charging control described in this chapter is integrated in the GSM part of the
XT55/56 and has been optimized for it only. When using the charging control
function for the entire XT55/56 module, please consider the current consumption of
the GPS part and your application. The value can be set with the AT^SBC
command. This command should be used to specify the power consumption if the
GSM part, the GPS part and your application are powered from the same battery.
For further details refer to [1].
For using the trickle charging functionality you should design the 470R (illustrated in
Figure 8) according to the current consumption of your application.
The module only delivers, via its GSM_POWER line and GSM_CHARGE line, the control
signals needed to start and stop the charging process. The charging circuit should include a
transistor and should be designed as illustrated in Figure 8. A list of parts recommended for
the external circuit is given in Table 7.
to GSM_POWER
Input from
charger
1SS355
470R
(5.5V - 8V)
to GSM_BATT+
under load
4V3
Battery
pack
PCB spark
gap
1/ ESDA6V1-5W6
CRS04
SI3441DV
NTC
100nF
10k
3k3
GSM_BATT_TEMP
1/ ESDA6V1-5W6
GSM_CHARGE
Figure 8: Schematic of approved charging transistor, trickle charging and ESD protection
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Table 7: Bill of material for external charging circuit
Part
Description
SI3441DV
p-chan 2.5V (G-S) MOSFET
VISHAY: SI3441DV-T1
(TSOP-6)
NEC:
1SS355
100mA Si-diode (UMD2)
ROHM:
Toshiba: 1SS352TPH3
CRS04
1A Schottky diode
Toshiba: CRS04
4V3
250mW; 200mA;
4.3V Z-Diode (SOD323)
Philips:
ESDA6V1-5W6
ESD protection TRANSIL™
STM:
array
470R, 3k3, 10k
Resistor, e.g. 0805 or 0603
100nF
Ceramic capacitor 50V
PCB spark gap
0.2mm spark gap on PCB
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1SS355TE-18
PDZ4.3B
ESDA6V1-5W6
Second supplier
UPA1911TE-T1
ROHM:
UDZS4.3B
UDZ4.3B
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3.5.1
Battery Pack Characteristics
The charging algorithm has been optimized for a Li-Ion battery pack that meets the
characteristics listed below. It is recommended that the battery pack you want to integrate
into your XT55/56 application is compliant with these specifications. This ensures reliable
operation, proper charging and, particularly, allows you to monitor the battery capacity using
the AT^SBC command (see [1] for details). Failure to comply with these specifications might
cause AT^SBC to deliver incorrect battery capacity values. A battery pack especially
designed to operate with XT55/56 modules is specified in Chapter 3.5.2.
•
•
•
•
•
•
•
Li-Ion battery pack specified for a maximum charging voltage of 4.2 V and a capacity of
800 mAh. Battery packs with a capacity down to 600 mAh or more than 800 mAh are
allowed, too.
Since charging and discharging largely depend on the battery temperature, the battery
pack should include an NTC resistor. If the NTC is not inside the battery it must be in
thermal contact with the battery. The NTC resistor must be connected between
GSM_BATT_TEMP and GND. Required NTC characteristics are: 10 kΩ +5% @ 25°C,
B25/85 = 3435K +3% (alternatively acceptable: 10 kΩ +2% @ 25°C, B25/50 = 3370K +3%).
Please note that the NTC is indispensable for proper charging, i.e. the charging process
will not start if no NTC is present.
Ensure that the pack incorporates a protection circuit capable of detecting overvoltage
(protection against overcharging), undervoltage (protection against deep discharging)
and overcurrent. The circuit must be insensitive to pulsed current.
On the XT55/56 module, a built-in measuring circuit constantly monitors the supply
voltage. In the event of undervoltage, it causes XT55/56 to power down. Undervoltage
thresholds are specific to the battery pack and must be evaluated for the intended model.
When you evaluate undervoltage thresholds, consider both the current consumption of
XT55/56 and of the application circuit.
The internal resistance of the battery and the protection should be as low as possible. It
is recommended not to exceed 150mΩ, even in extreme conditions at low temperature.
The battery cell must be insensitive to rupture, fire and gassing under extreme conditions
of temperature and charging (voltage, current).
The battery pack must be protected from reverse pole connection. For example, the
casing should be designed to prevent the user from mounting the battery in reverse
orientation.
The battery pack must be approved to satisfy the requirements of CE conformity.
Figure 9 shows the circuit diagram of a to GSM_BATT+ to GSM_BATT_TEMP
typical battery pack design that includes
the protection elements described
ϑ
above.
to GND
NTC
Protection Circuit
Figure 9: Battery pack circuit diagram
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3.5.2
Recommended Battery Pack Specification
Table 8: Specifications of recommended battery pack
Battery type
Li-Ion
Nominal voltage
3.6V
Capacity
800mAh
NTC
10kΩ ± 5% @ 25°C, B (25/85)=3435K ± 3%
Overcharge detection voltage
4.325 ± 0.025V
Overcharge release voltage
4.075 ± 0.025V
Overdischarge detection voltage
2.5 ± 0.05V
Overdischarge release voltage
2.9 ± 0.5V
Overcurrent detection
3 ± 0.5A
Nominal working current
<5µA
Current of low voltage detection
0.5µA
Overcurrent detection delay time
8~16ms
Short detection delay time
50µs
Overdischarge detection delay time
31~125ms
Overcharge detection delay time
1s
Internal resistance
<130mΩ
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3.5.3
Implemented Charging Technique
If the external charging circuit follows the recommendation of Figure 8, the charging process
consists of trickle charging and processor controlled fast charging. For this solution, the fast
charging current provided by the charger or any other external source must be limited to
500mA.
Trickle charging
• Trickle charging starts when the charger is connected to the charger input of the external
charging circuit and the module’s GSM_POWER pin. The charging current depends on
the voltage difference between the charger input of the external charging circuit and
GSM_BATT+ of the module.
• Trickle charging stops when the battery voltage reaches 3.6V.
Fast charging
After trickle charging has raised the battery voltage to 3.2V within 60 minutes +10% from
connecting the charger, the power ASIC turns on and wakes up the baseband processor.
Now, processor controlled fast charging begins.
However, if the battery was deeply discharged (below 2.2V) the power ASIC does not
wake up the baseband processor and fast charging does not begin after the battery
voltage has reached 3.2V. In this case, disconnect and reconnect the charger once after
the battery voltage has risen above 2.2V.
If the battery voltage was already above 3.2V, processor controlled fast charging starts
just after the charger was connected to the charger input of the external charging circuit
and the module’s GSM_POWER pin. If the GSM part of the XT55/56 was in POWER
DOWN mode, it turns on and enters the Charge-only mode along with fast charging (see
also Chapter 3.3.1.3).
• Fast charging delivers a constant current until the battery voltage reaches 4.2V and then
proceeds with varying charge pulses. As shown in Figure 5, the pulse duty cycle is
reduced to adjust the charging procedure and prevent the voltage from overshooting
beyond 4.2V. Once the pulse width reaches the minimum of 100ms and the duty cycle
does not change for 2 minutes, fast charging is completed.
After the end of charging the battery voltage falls due to discharging. Once the voltage
falls below 4.0V (approximately), the charging process begins again.
• Fast charging can only be accomplished in a temperature range from 0°C to +45°C.
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Voltage
4.3
4.2
End of
charging
3.8
3.4
100ms 2 ... 0.1s
100ms 0.1 ... 2s
3.0
Constant current
tOFF = 100 ms
tON = 100 ms
Time
Figure 10: Charging process
Note:
Do not connect the charger to the GSM_BATT+ lines. Only the charger input of the
external charging circuit is intended as input for charging current! The
GSM_POWER pin of XT55/56 is the input only for indicating a connected charger!
The battery manufacturer must guarantee that the battery complies with the
described charging technique.
What to do if software controlled charging does not start up?
If trickle charging fails to raise the battery voltage to 3.2V within 60 minutes +10%, processor
controlled charging does not begin. To start fast charging you can do one of the following:
• Once the voltage has risen above its minimum of 3V, you can try to start software
controlled charging by pulling the GSM_IGT line to ground.
• If the voltage is still below 3V, driving the GSM_IGT line to ground switches the timer off.
Without the timer running, the GSM part of the XT55/56 module will not proceed to
software controlled charging. To restart the timer you are required to shortly disconnect
and reconnect the charger.
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3.5.4
Operating Modes during Charging
Of course, the battery can be charged regardless of the engine's operating mode. When the
GSM engine is in Normal mode (SLEEP, IDLE, TALK, GPRS IDLE or GPRS DATA mode), it
remains operational while charging is in progress (provided that sufficient voltage is applied).
The charging process during the Normal mode is referred to as Charge mode.
If the charger is connected to the charger input of the external charging circuit and the
module’s GSM_POWER pin while GSM part of XT55/56 is in POWER DOWN mode, the
GSM part of the XT55/56 goes into Charge-only mode.
Table 9: Comparison Charge-only and Charge mode
Charge-only mode
Charge mode
How to activate mode
Features
Connect charger to charger input of • Battery can be charged while GSM engine
external charging circuit and module’s
remains operational and registered to the
GSM_POWER pin while the GSM part of
GSM network.
the XT55/56 is
• In IDLE and TALK mode, the serial interfaces
are accessible. AT command set can be used
• operating, e.g. in IDLE or TALK mode
to full extent.
• in SLEEP mode
• In the NON-CYCLIC SLEEP mode, the serial
interfaces are not accessible at all. During the
CYCLIC SLEEP mode they can be used as
described in Chapter 3.6.3.
Connect charger to charger input of • Battery can be charged while GSM engine is
external charging circuit and module’s
deregistered from GSM network.
GSM_POWER pin while the GSM part of • Charging runs smoothly due to constant
the XT55/56 is
current consumption.
• The AT interface is accessible and allows to
• in POWER DOWN mode
use the commands listed below.
• in Normal mode: Connect charger to
the GSM_POWER pin, then enter
AT^SMSO.
IMPORTANT: While trickle charging is in
progress, be sure that the application is
switched off. If the application is fed from
the trickle charge current the module
might be prevented from proceeding to
software controlled charging since the
current would not be sufficient.
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Features of Charge-only mode
Once the GSM engine enters the Charge-only mode, the AT command interface presents an
Unsolicited Result Code (URC) which reads:
^SYSSTART CHARGE-ONLY MODE
Note that this URC will not appear when autobauding was activated (due to the missing
synchronization between DTE and DCE upon start-up). Therefore, it is recommended to
select a fixed baudrate before using the Charge-only mode.
While the Charge-only mode is in progress, you can only use the AT commands listed in
Table 10. For further instructions refer to the AT Command Set supplied with your GSM
engine.
Table 10: AT commands available in Charge-only mode
AT command
Function
AT+CALA
Set alarm time
AT+CCLK
Set date and time of RTC
AT^SBC
Monitor charging process
AT^SCTM
AT^SMSO
Note: While charging is in progress, no battery capacity value is available. To query
the battery capacity disconnect the charger.
If the charger connects externally to the host device no charging parameters are
transferred to the module. In this case, the command cannot be used.
Query temperature range, enable/disable URCs to report critical temperature
ranges
Power down GSM engine
To proceed from Charge-only mode to normal operation, it is necessary to drive the ignition
line to ground. This must be implemented in your host application as described in Chapter
3.3.1.1. See also Chapter 3.7 which summarizes the various options of changing the mode of
operation.
If your host application uses the GSM_SYNC pin to control a status LED as described in
Chapter 3.12.2.2, please note that the LED is off while the GSM engine is in Charge-only
mode.
3.5.5
Charger Requirements
If you are using the implemented charging technique and the charging circuit recommended
in Figure 8, the charger must be designed to meet the following requirements:
a) Simple transformer power plug
- Output voltage: 5.5V...8V (under load)
- The charge current must be limited to 500mA
- Voltage spikes that may occur while you connect or disconnect the charger must be
limited.
- There must not be any capacitor on the secondary side of the power plug (avoidance of
current spikes at the beginning of charging)
b) Supplementary requirements for a) to ensure a regulated power supply
- When current is switched off a voltage peak of 10V is allowed for a maximum 1ms
- When current is switched on a spike of 1.6A for 1ms is allowed
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3.6
Power Saving
SLEEP mode reduces the functionality of the GSM part of the XT55/56 module to a minimum
and, thus, minimizes the current consumption to the lowest level. Settings can be made
using the AT+CFUN command. For details see below and [1]. SLEEP mode falls into two
categories:
• NON-CYCLIC SLEEP mode AT+CFUN=0
• CYCLIC SLEEP modes, selectable with AT+CFUN=5, 6, 7, 8 or 9.
IMPORTANT: Please keep in mind that power saving works properly only when PIN
authentication has been done. If you attempt to activate power saving while the SIM card is
not inserted or the PIN not correctly entered (Limited Service), the selected  level will
be set, though power saving does not take effect. For the same reason, power saving cannot
be used if the GSM part of the XT55/56 operates in Alarm mode.
To check whether power saving is on, you can query the status of AT+CFUN if you have
chosen CYCLIC SLEEP mode. If available, you can take advantage of the status LED
controlled by the GSM_SYNC pin (see Chapter 3.12.2.2). The LED is off in all SLEEP modes
when no activity occurs, but resumes flashing to indicate temporary wake-up states during
CYLCIC SLEEP modes. The LED patterns are shown in Table 18.
The wake-up procedures are quite different depending on the selected SLEEP mode. Table
11 compares the wake-up events that can occur in NON-CYCLIC and CYCLIC SLEEP
modes.
3.6.1
No Power Saving (AT+CFUN=1)
The functionality level =1 is where power saving is switched off. This is the default after
startup.
3.6.2
NON-CYCLIC SLEEP Mode (AT+CFUN=0)
If level 0 has been selected (AT+CFUN=0), the serial interface is blocked. The module
shortly deactivates power saving to listen to a paging message sent from the base station
and then immediately resumes power saving. Level 0 is called NON-CYCLIC SLEEP mode,
since the serial interface is not alternatingly made accessible as in CYCLIC SLEEP mode.
The first wake-up event fully activates the module, enables the serial interface and
terminates the power saving mode. In short, it takes the GSM part of the XT55/56 back to the
highest level of functionality =1.
In NON-CYCLIC mode, the falling edge of the GSM_RTS0 or GSM_RTS1 lines wakes up the
module to =1. To efficiently use this feature it is recommended to enable hardware flow
control (RTS/CTS handshake) as in this case the GSM_CTS line notifies the application
when the module is ready to send or receive characters. See section 3.6.5.1 for details.
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3.6.3
CYCLIC SLEEP Mode (AT+CFUN=5, 6, 7, 8)
The major benefit over the NON-CYCLIC SLEEP mode is that the serial interface is not
permanently blocked and that packet switched calls may go on without terminating the
selected CYCLIC SLEEP mode. This allows the GSM part of the XT55/56 to become active,
for example to perform a GPRS data transfer, and to resume power saving after the GPRS
data transfer is completed.
The CYCLIC SLEEP modes give you greater flexibility regarding the wake-up procedures:
For example, in all CYCLIC SLEEP modes, you can enter AT+CFUN=1 to permanently wake
up the module. In modes CFUN=7 and 8, the GSM part of the XT55/56 automatically
resumes power saving, after you have sent or received a short message or made a call.
CFUN=5 and 6 do not offer this feature, and therefore, are only supported for compatibility
with earlier releases. Please refer to Table 11 for a summary of all modes.
The CYCLIC SLEEP mode is a dynamic process which alternatingly enables and disables
the serial interface. By setting/resetting the GSM_CTS signal, the module indicates to the
application whether or not the UART is active. The timing of GSM_CTS is described below.
Both the application and the module must be configured to use hardware flow control
(RTS/CTS handshake). The default setting of the GSM part of the XT55/56 is AT\Q0 (no flow
control) which must be altered to AT\Q3. See [1] for details.
Note: If both serial interfaces ASC0 and ASC1 are connected, both are synchronized. This
means that SLEEP mode takes effect on both, no matter on which interface the AT
command was issued. Although not explicitly stated, all explanations given in this
chapter refer equally to ASC0 and ASC1, and accordingly to GSM_CTS0 and
GSM_CTS1.
3.6.4
CYCLIC SLEEP Mode AT+CFUN=9
Mode AT+CFUN=9 is similar to AT+CFUN=7 or 8, but provides two additional features:
• The time the module stays active after GSM_RTS was asserted or after the last character
was sent or received, can be configured individually using the command AT^SCFG.
Default setting is 2 seconds like in AT+CFUN=7. The entire range is from 0.5 seconds to
1 hour, selectable in tenths of seconds. For details see [1].
• GSM_RTS0 and GSM_RTS1 are not only used for flow control (as in modes
AT+CFUN=5, 6, 7 or 8), but also cause the module to wake up temporarily. See section
3.6.5.1 for details.
3.6.5
Timing of the GSM_CTS Signal in CYCLIC SLEEP Modes
The GSM_CTS signal is enabled in synchrony with the module’s paging cycle. It goes active
low each time when the module starts listening to a paging message block from the base
station. The timing of the paging cycle varies with the base station. The duration of a paging
interval can be calculated from the following formula:
4.615 ms (TDMA frame duration) * 51 (number of frames) * DRX value.
DRX (Discontinuous Reception) is a value from 2 to 9, resulting in paging intervals from 0.47
to 2.12 seconds. The DRX value of the base station is assigned by the network operator.
Each listening period causes the GSM_CTS signal to go active low: If DRX is 2, the
GSM_CTS signal is activated every 0.47 seconds, if DRX is 3, the GSM_CTS signal is
activated every 0.71 seconds and if DRX is 9, the GSM_CTS signal is activated every 2.1s.
The GSM_CTS signal is active low for 4.6 ms. This is followed by another 4.6 ms UART
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activity. If the start bit of a received character is detected within these 9.2 ms, GSM_CTS will
be activated and the proper reception of the character will be guaranteed.
GSM_CTS will also be activated if any character is to be sent.
After the last character was sent or received the interface will remain active for
• another 2 seconds, if AT+CFUN=5 or 7,
• another 10 minutes, if AT+CFUN=6 or 8,
• or for an individual time defined with AT^SCFG, if AT+CFUN=9. Assertion of GSM_RTS
has the same effect.
In the pauses between listening to paging messages, while GSM_CTS is high, the module
resumes power saving and the AT interface is not accessible. See Figure 11 and Figure 12.
Paging message
Paging message
2.12 s
Paging message
4.6
4.6
ms
GSM _CTS ms
4.6 ms
4.6
ms
4.6
ms
4.6 ms
AT interface disabled
Paging message
2.12 s
2.12 s
4.6 ms
4.6 ms
AT interface enabled
Figure 11: Timing of CTS signal (example for a 2.12 s paging cycle)
Figure 12 illustrates the CFUN=5 and CFUN=7 modes, which reset the GSM_CTS signal 2
seconds after the last character was sent or received.
Paging message
2.12 s
Paging message
2.12 s
Paging message
2.12 s
Paging message
Beginning of power saving
4.6
ms
GSM_CTS
2s
st
1 character
4.6 ms
4.6
ms
4.6 ms
4.6 ms
Last character
AT interface disabled
AT interface enabled
Figure 12: Beginning of power saving if CFUN=5 or 7
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Wake up XT55/56 from SLEEP Mode
A wake-up event is any event that causes the module to draw current. Depending on the
selected mode the wake-up event either switches SLEEP mode off and takes XT55/56 back
to AT+CFUN=1, or activates XT55/56 temporarily without leaving the current SLEEP mode.
Definitions of the state transitions described in Table 11:
Quit
= XT55/56 exits SLEEP mode and returns to AT+CFUN=1.
Temporary
= XT55/56 becomes active temporarily for the duration of the event and the
mode-specific follow-up time after the last character was sent or received
on the serial interface.
No effect:
= Event is not relevant in the selected SLEEP mode. XT55/56 does not
wake up.
Table 11: Wake-up events in NON-CYCLIC and CYCLIC SLEEP modes
Event
Ignition line
GSM_RTS0 or GSM_RTS1
(falling edge)
1)
Selected mode
AT+CFUN=0
Selected mode
AT+CFUN=5 or 6
Selected mode
AT+CFUN=7, 8, 9
No effect
No effect
No effect
Quit + flow control
No effect, GSM_RTS
is only used for flow
control
Mode 7 and 8: No
effect, GSM_RTS is
only used for flow
control
Mode 9: Temporary +
flow control
Unsolicited Result Code
(URC)
Quit
Quit
Temporary
Incoming voice or data call
Quit
Quit
Temporary
Any AT command
(incl. outgoing voice or data
call, outgoing SMS)
Not possible
(UART disabled)
Temporary
Temporary
AT+CNMI=0,0 (= default, no
indication of received SMS)
No effect
No effect
No effect
AT+CNMI=1,1 (= displays
URC upon receipt of SMS)
Quit
Quit
Temporary
GPRS data transfer
Not possible
(UART disabled)
Temporary
Temporary
RTC alarm
Quit2)
Quit
Temporary
AT+CFUN=1
Not possible
(UART disabled)
Quit
Quit
Incoming SMS depending on
mode selected by AT+CNMI:
1)
2)
See section 3.6.5.1 on wake-up via GSM_RTS.
Recommendation: In NON-CYCLIC SLEEP mode, you can set an RTC alarm to wake
up XT55/56 and return to full functionality. This is a useful approach because, in this
mode, the AT interface is not accessible.
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3.6.5.1
Wake-up via /RTS0 and RTS1 (if AT+CFUN=0 or AT+CFUN=9)
During the CYCLIC SLEEP modes 5, 6, 7, and 8, GSM_RTS0 and GSM_RTS1 are
conventionally used for flow control: The assertion of GSM_RTS0 or GSM_RTS1 indicates
that the application is ready to receive data - without waking up the module.
If the module is in CFUN=0 mode the assertion of GSM_RTS0 and GSM_RTS1 serves as a
wake-up event, giving the application the possibility to intentionally terminate power saving. If
the module is in CFUN=9 mode, the assertion of GSM_RTS0 or GSM_RTS1 can be used to
temporarily wake up XT55/56 for the time specified with the AT^SCFG command (default =
2s). In both cases, if GSM_RTS0 or GSM_RTS1 is asserted while AT+CFUN=0 or
AT+CFUN=9 is set, there may be a short delay until the module is able to receive data again.
This delay depends on the current module activities (e.g. paging cycle) and may be up to
60ms. The ability to receive data is signalized by GSM_CTS0 and GSM_CTS1. It is therefore
recommended to enable RTS/CTS flow control, not only in CYCLIC SLEEP mode, but also in
NON-CYCLIC SLEEP mode.
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3.7
Summary of State Transitions (Except SLEEP Mode)
Table 12: State transitions of XT55/56 (except SLEEP mode)
The table shows how to proceed from one GSM mode to another (grey column = present mode, white columns = intended modes)
POWER DOWN
Normal mode**)
Charge-only mode*)
Charging in normal mode*)**)
Alarm mode
POWER DOWN mode
without charger
---
GSM_IGT >100 ms at
low level
Connect charger to input
of ext. charging circuit and
GSM_POWER pin (high
level at GSM_POWER)
No direct transition, but via
“Charge-only mode” or
“Normal mode”
Wake-up from POWER
DOWN mode (if activated
with AT+CALA)
POWER DOWN mode
with charger (high level
at GSM_POWER pin of
XT55/56)
---
GSM_IGT >1 s at low
level, if battery is fully
charged
100ms < GSM_IGT <
500ms at low level
GSM_IGT >1 s at low level
Wake-up from POWER
DOWN mode (if activated
with AT+CALA)
Normal mode**)
AT^SMSO
or exceptionally
GSM_EMERGOFF pin > 3.2s
at low level
---
No automatic transition,
but via “POWER DOWN”
Connect charger to
GSM_POWER pin at
XT55/56 (high level at
GSM_POWER)
AT+CALA followed by
AT^SMSO. XT55/56 enters
Alarm mode when specified
time is reached.
Charge-only mode *)
Disconnect charger (XT55/56
GSM_POWER pin at low
level)
or AT^SMSO
or exceptionally
GSM_EMERGOFF pin >3.2s
at low level
--No automatic transition,
but via “Charge in Normal
mode”
GSM_IGT >1s at low level
AT+CALA followed by
AT^SMSO. XT55/56 enters
Alarm mode when specified
time is reached and
VGSM_BATT+>3.2V
Charging in normal
mode*) **)
AT^SMSO Î “Charge-only
mode”, again AT^SMSO
or exceptionally
GSM_EMERGOFF pin >3.2s
at low level
Disconnect charger from
input of ext. charging
circuit and module’s
GSM_POWER pin
---
No direct transition
Alarm mode
AT^SMSO or exceptionally
GSM_EMERGOFF pin >3.2s
at low level
GSM_IGT >100ms at low AT^SMSO if charger is
level
connected
GSM_IGT >100ms at low
level
---
Further mode ÎÎÎ
Present mode
*)
See Chapter 3.5.4 for details on the charging mode
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**)
AT^SMSO
Normal mode covers TALK, DATA, GPRS, IDLE and SLEEP modes
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3.8
RTC Backup for GSM Part of XT55/56
The internal Real Time Clock of the XT55/56 GSM part is supplied from a separate voltage
regulator in the power supply ASIC which is also active when the GSM part of the XT55/56 is
in POWER DOWN status. An alarm function is provided that allows to wake up XT55/56
without logging on to the GSM network.
In addition, you can use the GSM_VDDLP pin on the board-to-board connector to backup the
RTC from an external capacitor or a battery (rechargeable or non-chargeable). The capacitor
is charged by the GSM_BATT+ line of XT55/56. If the voltage supply at GSM_BATT+ is
disconnected the RTC can be powered by the capacitor. The size of the capacitor
determines the duration of buffering when no voltage is applied to the GSM part of the
XT55/56, i.e. the greater capacitor the longer the GSM part of the XT55/56 will save the date
and time.
The following figures show various sample configurations. The voltage applied at
GSM_VDDLP can be in the range from 2 to 5.5V. Please refer to Table 27 for the
parameters required.
GSM_BATT+
Baseband
processor
B2B
PSU
GSM_VDDLP
1k
RTC
Figure 13: RTC supply from capacitor
GSM_BATT+
Baseband
processor
B2B
PSU
GSM_VDDLP
1k
RTC
Figure 14: RTC supply from rechargeable battery
GSM_BATT+
Baseband
processor
B2B
PSU
1k
GSM_VDDLP
RTC
Figure 15: RTC supply from non-chargeable battery
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3.9
Serial Interfaces of the XT55/56 GSM Part
The GSM part of the XT55/56 module offers two unbalanced, asynchronous serial interfaces
conforming to ITU-T V.24 protocol DCE signaling. The electrical characteristics do not
comply with ITU-T V.28. The significant levels are 0V (for low data bit or ON condition) and
2.65V (for high data bit or OFF condition). For electrical characteristics please refer to Table
38. Figure 2 shows the serial interfaces of the XT55/56 module.
The GSM engine is designed for use as a DCE. Based on the conventions for DCE-DTE
connections it communicates with the customer application (DTE) using the following signals:
ASC0
• Port TXD @ application sends data to the module’s GSM_TXD0 signal line
• Port RXD @ application receives data from the module’s GSM_RXD0 signal line
ASC1
• Port TXD @ application sends data to module’s GSM_TXD1 signal line
• Port RXD @ application receives data from the module’s GSM_RXD1 signal line
3.9.1
•
•
•
•
•
•
•
•
Features of the first Serial Interface of the GSM Part (ASC0)
8-wire serial interface
Includes the data lines GSM_TXD0 and GSM_RXD0, the status lines GSM_RTS0 and
GSM_CTS0 and, in addition, the modem control lines GSM_DTR0, GSM_DSR0,
GSM_DCD0 and GSM_RING0.
It is primarily designed for voice calls, CSD calls, fax calls and GPRS services and for
controlling the GSM engine with AT commands. Full Multiplex capability allows the
interface to be partitioned into three virtual channels, yet with CSD and fax services only
available on the first logical channel. Please note that when the ASC0 interface runs in
Multiplex mode, ASC1 cannot be used. For more detailed characteristics see [13].
The GSM_DTR0 signal will only be polled once per second from the internal firmware of
XT55/56.
The GSM_RING0 signal serves to indicate incoming calls and other types of URCs
(Unsolicited Result Code). It can also be used to send pulses to the host application, for
example to wake up the application from power saving state. For further details see
Chapter 3.12.3.
Autobauding is only selectable on ASC0 and supports the following bit rates: 1200, 2400,
4800, 9600, 19200, 38400, 57600, 115200, 230400 bps.
Autobauding is not compatible with multiplex mode, see [13].
ASC0 interface is intended for firmware upgrade of the GSM part
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3.9.2
•
•
•
4-wire serial interface
Includes only the data lines GSM_TXD1 and GSM_RXD1 plus GSM_RTS1 and
GSM_CTS1 for hardware handshake. This interface is intended for voice calls, GPRS
services and for controlling the GSM engine with AT commands. It is not suited for CSD
calls, fax calls and Multiplex mode.
On ASC1 no GSM_RING line is available. The indication of URCs on the second
interface depends on the settings made with the AT^SCFG command. For details refer to
[1].
3.9.3
•
•
Features of the second Serial Interface of GSM Part (ASC1)
ASC0 and ASC1 Configuration
Both interfaces are configured for 8 data bits, no parity and 1 stop bit, and can be
operated at bit rates from 300bps to 230400 bps.
XON/XOFF software flow control can be used on both interfaces (except if power saving
is active).
Table 13: DCE-DTE wiring of 1st serial interface (GSM part)
V.24
circuit
DCE (XT55/56)
DTE (application)
Pin function
Signal direction
Pin function
Signal direction
103
GSM_TXD0
Input
/TXD
Output
104
GSM_RXD0
Output
/RXD
Input
105
GSM_RTS0
Input
/RTS
Output
106
GSM_CTS0
Output
/CTS
Input
108/2
GSM_DTR0
Input
/DTR
Output
107
GSM_DSR0
Output
/DSR
Input
109
GSM_DCD0
Output
/DCD
Input
125
GSM_RING0
Output
/RING
Input
Table 14: DCE-DTE wiring of 2nd serial interface (GSM part)
V.24
circuit
DCE (XT55/56)
DTE (application)
Pin function
Signal direction
Pin function
Signal direction
103
GSM_TXD1
Input
/TXD
Output
104
GSM_RXD1
Output
/RXD
Input
105
GSM_RTS1
Input
/RTS
Output
106
GSM_CTS1
Output
/CTS
Input
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3.10
Audio Interfaces
XT55/56 comprises three audio interfaces available on the board-to-board connector:
• Two analog audio interfaces, each with a balanced analog microphone input and a
balanced analog earpiece output. The second analog interface provides a supply circuit
to feed an active microphone.
• Serial digital audio interface (DAI) using PCM (Pulse Code Modulation) to encode analog
voice signals into digital bit streams.
This means you can connect up to three audio devices in any combination, although analog
and digital audio cannot be operated at the same time. Using the AT^SAIC command you
can easily switch back and forth.
GSM_MICP1
GSM_MICN1
GSM_MICP2
ADC
GSM_MICN2
GSM_EPP1
GSM_EPN1
DAC
GSM_EPP2
DSP
Air
Interface
GSM_EPN2
GSM_SCLK
GSM_RXDDA
GSM_RFSDAI
GSM_TXDDAI
GSM_TFSDAI
Digital
Audio
Interface
(DAI)
Figure 16: Audio block diagram
XT55/56 offers six audio modes which can be selected with the AT^SNFS command, no
matter which of the three interfaces is currently active. The electrical characteristics of the
voiceband part vary with the audio mode. For example, sending and receiving amplification,
sidetone paths, noise suppression etc. depend on the selected mode and can be altered with
AT commands (except for mode 1).
On each audio interface you can use all audio AT commands specified in [1] to alter
parameters. The only exception are the DAC and ADC gain amplifier attenuation
 and  which cannot be modified when the digital audio interface is
used, since in this case the DAC and ADC are switched off.
Please refer to Chapter 3.10 for specifications of the audio interface and an overview of the
audio parameters. Detailed instructions on using AT commands are presented in [1]. Table
31 on page 105 summarizes the characteristics of the various audio modes and shows what
parameters are supported in each mode.
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When shipped from factory, all audio parameters of XT55/56 are set to interface 1 and audio
mode 1. This is the default configuration optimized for the Votronic HH-SI-30.3/V1.1/0
handset and used for type approving the Siemens reference configuration. Audio mode 1 has
fix parameters which cannot be modified. To adjust the settings of the Votronic handset
simply change to another audio mode.
In transmit direction, all audio modes contain internal scaling factors (digital amplification)
that are not accessible by the user. To avoid saturation with a full scale digital input signal on
the DAI, and to obtain a one-to-one digital access to the speech coder in audio mode 5
and 6, it is recommended to set the parameter  of the selected audio mode as
follows:
Audio mode 1 and 4:
23196
Audio mode 2:
17396
Audio mode 3:
21901
Audio mode 5 and 6:
21402
3.10.1
Microphone Circuit
Interface 1
This interface has no microphone supply circuit and therefore, has an impedance of 50kΩ.
When connecting a microphone or another signal source to interface 1 you are required to
add two 100 nF capacitors, one to each line.
Interface 2
This interface comes with a microphone supply circuit and can be used to feed an active
microphone. It has an impedance of 2kΩ. If you do not use it or if you want to connect
another type of signal source, for example, an op amp or a dynamic microphone, it needs to
be decoupled with capacitors. The power supply can be switched off and on by using the
command AT^SNFM. For details see [1].
Figure 17 shows the microphone inputs at both analog interfaces of XT55/56.
2.65 V
Power down
GSM_MICP1
GSM_MICN1
Ri=50kΩ
to ADC
1 kΩ
1 kΩ
GSM_MICP2
33 µF
GSM_MICN2
1 kΩ
1 kΩ
Ri=2kΩ
Figure 17: Schematic of microphone inputs
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3.10.2
Speech Processing
The speech samples from the ADC or DAI are handled by the DSP of the baseband
controller to calculate e.g. amplifications, sidetone, echo cancellation or noise suppression
depending on the configuration of the active audio mode. These processed samples are
passed to the speech encoder. Received samples from the speech decoder are passed to
the DAC or DAI after post processing (frequency response correction, adding sidetone etc.).
Full rate, half rate, enhanced full rate, adaptive multi rate (AMR), speech and channel
encoding including voice activity detection (VAD) and discontinuous transmission (DTX) and
digital GMSK modulation are also performed on the GSM baseband processor.
Customer specific audio parameters can be evaluated and supplied by Siemens on request.
These parameters can be downloaded to XT55/56 using an AT command. For further
information refer to [10] or contact your Siemens distributor.
3.10.3
DAI Timing
To support the DAI function, XT55/56 integrates a simple five-line serial interface with one
input data clock line (GSM_SCLK) and input / output data and frame lines (GSM_TXDDAI,
GSM_TFSDAI, GSM_RXDDAI, GSM_RFSDAI).
The serial interface is always active if the external input data clock GSM_SLCK is present,
i.e. the serial interface is not clocked by the DSP of the XT55/56 baseband processor.
GSM_SLCK must be supplied from the application and can be in a frequency range between
0.2 and 10 MHz. Serial transfer of 16-bit words is done in both directions.
Data transfer to the application is initiated by the module via a short pulse of GSM_TFSDAI.
The duration of the GSM_TFSDAI pulse is one GSM_SCLK period, starting at the rising
edge of SLCK. During the following 16 SLCK cycles, the 16-bit sample will be transferred on
the GSM_TXDDAI line. The next outgoing sample will be transferred after the next
GSM_TFSDAI pulse which occurs every 125 µs.
The GSM_TFSDAI pulse is the master clock of the sample transfer. From the rising edge of
the GSM_TFSDAI pulse, the application has 100 µs to transfer the 16-bit input sample on the
GSM_RXDDAI line. The rising edge of the GSM_RFSDAI pulse (supplied by the application)
may coincide with the falling edge of GSM_TFSDAI or occur slightly later - it is only
significant that, in any case, the transfer of the LSB input sample will be completed within the
specified duration of 100 µs.
Audio samples are transferred from the module to the application in an average of 125µs.
This is determined by the 8kHz sampling rate, which is derived from and synchronized to the
GSM network. As SLCK is independent of the GSM network, the distance between two
succeeding sample transfers may vary about + 1 SLCK period.
The application is required to adapt its sampling rate to the GSM_TFSDAI rate. Failure to
synchronize the timing between the module and the application may cause audible pops and
clicks in a conversation. The timing characteristics of both data transfer directions are shown
in Figure 18 and Figure 19.
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Note:
Before starting the data transfer the clock GSM_SCLK should be available for at
least three cycles.
After the transfer of the LSB0 the clock GSM_SCLK should be still available for at
least three cycles.
minimum possible distance = 25 bit periods
GSM_SLCK
(input)
=T
T = 100ns to 5,000 ns
Internal
signal
GSM_RFSDAI
(input)
=T
GSM_RXDDAI
=T
MSB
15
(input)
Bit
14
Bit
13
Bit
12
Bit
11
Bit
10
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
LSB
MSB
15
< 1 DSP cycle
Flag
< 1.5 SCLK
cycles
automatic reset after
reading to DAIRD
interrupt on INTO
after 3 DSP cycles
Figure 18: DAI timing on transmit path
minimum possible distance = 25 bit periods
GSM_SLCK
(input)
=T
T = 100ns to 5,000 ns
Internal
signal
GSM_TFSDAI
<3 SCLK
cycles
(output)
=T
GSM_TXDDAI
(output)
Flag
MSB
15
Bit
14
=T
Bit
13
Bit
12
Bit
11
Bit
10
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
Bit
LSB
MSB
15
automatic reset after
writing to DAITD
<1 DSP
cycles
interrupt on INTO
after 3 DSP cycles
<2 DSP
cycles
Figure 19: DAI timing on receive path
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3.11
SIM Interface
The baseband processor has an integrated SIM interface compatible with the ISO 7816 IC
Card standard. This is wired to the host interface (board-to-board connector) in order to be
connected to an external SIM card holder. Six pins on the board-to-board connector are
reserved for the SIM interface.
The GSM_CCIN pin serves to detect whether a tray (with SIM card) is present in the card
holder. Using the GSM_CCIN pin is mandatory for compliance with the GSM 11.11
recommendation if the mechanical design of the host application allows the user to remove
the SIM card during operation. See Chapter 3.11.1 for details.
Table 15: Signals of the SIM interface (board-to-board connector)
Signal
Description
GSM_CCGND
Separate ground connection for SIM card to improve EMC.
GSM_CCCLK
Chipcard clock, various clock rates can be set in the baseband processor.
GSM_CCVCC
SIM supply voltage from PSU-ASIC
GSM_CCIO
Serial data line, input and output.
GSM_CCRST
Chipcard reset, provided by baseband processor.
GSM_CCIN
Input on the baseband processor for detecting a SIM card tray in the holder.
The GSM_CCIN pin is mandatory for applications that allow the user to remove the
SIM card during operation.
The GSM_CCIN pin is solely intended for use with a SIM card. It must not be used
for any other purposes. Failure to comply with this requirement may invalidate the
type approval of XT55/56.
It is recommended that the total cable length between the board-to-board connector pins on
XT55/56 and the pins of the SIM card holder does not exceed 200 mm in order to meet the
specifications of 3GPP TS 51.010-1 and to satisfy the requirements of EMC compliance.
To avoid possible cross-talk from the GSM_CCCLK signal to the GSM_CCIO signal be
careful that both lines are not placed closely next to each other. A useful approach is using
the GSM_CCGND line to shield the GSM_CCIO line from the GSM_CCCLK line.
Furthermore connect a 47 pF capacitor from the GSM_CCIO to the GSM_CCGND line.
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3.11.1
Requirements for Using the GSM_CCIN Pin
According to ISO/IEC 7816-3 the SIM interface must be immediately shut down once the SIM
card is removed during operation. Therefore, the signal at the GSM_CCIN pin must go low
before the SIM card contacts are mechanically detached from the SIM interface contacts.
This shut-down procedure is particularly required to protect the SIM card as well as the SIM
interface of XT55/56 from damage.
An appropriate SIM card detect switch is required on the card holder. For example, this is
true for the model supplied by Molex, which has been tested to operate with XT55/56 and is
part of the Siemens reference equipment submitted for type approval. Molex ordering
number is 91228-0001, see also Chapter 10.
The module’s startup procedure involves a SIM card initialization performed within 1 second
after getting started. An important issue is whether the initialization procedure ends up with a
high or low level of the GSM_CCIN signal:
a)
If, during startup of XT55/56, the GSM_CCIN signal on the SIM interface is high, then
the status of the SIM card holder can be recognized each time the card is inserted or
ejected.
A low level of GSM_CCIN indicates that no SIM card tray is inserted into the holder. In
this case, the module keeps searching, at regular intervals, for the SIM card. Once the
SIM card tray with a SIM card is inserted, GSM_CCIN is taken high again.
b)
If, during startup of XT55/56, the GSM_CCIN signal is low, the module will also attempt
to initialize the SIM card. In this case, the initialization will only be successful when the
card is present.
If the SIM card initialization has been done, but the card is no more operational or
removed, then the module will never search again for a SIM card and only emergency
calls can be made.
Removing and inserting the SIM card during operation requires the software to be
reinitialized. Therefore, after reinserting the SIM card it is necessary to restart XT55/56.
It is strongly recommended to connect the contacts of the SIM card detect switch to the
GSM_CCIN input and to the GSM_CCVCC output of the module as illustrated in the sample
diagram in Figure 20.
Note: No guarantee can be given, nor any liability accepted, if loss of data is encountered
after removing the SIM card during operation.
Also, no guarantee can be given for properly initializing any SIM card that the user
inserts after having removed a SIM card during operation. In this case, the application
must restart XT55/56.
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3.11.2
Design Considerations for SIM Card Holder
The schematic below is a sample configuration that illustrates the Molex SIM card holder
located on the DSB45 Support Box (evaluation kit used for type approval of the Siemens
XT55/56 reference setup, see [9]). X503 is the designation used for the SIM card holder in
[9].
GSM_CCVCC
GSM_CCIN
GSM_CCIO
GSM_CCCLK
GSM_CCRST
47pF
GSM_CCGND
Molex card holder
GSM module
Figure 20: SIM card holder of DSB45 Support Box
Table 16: Pin assignment of Molex SIM card holder on DSB45 Support Box
Pin no. Signal name
I/O
Function
CCVCC
Supply voltage for SIM card, generated by the GSM engine
CCRST
Chip card reset, prompted by the GSM engine
CCCLK
Chip card clock
CCGND
Individual ground line for the SIM card to improve EMC
CCVPP
Not connected
CCIO
I/O
Serial data line, bi-directional
CCDET1
Connect to GSM_CCVCC
CCDET2
Connects to the GSM_CCIN input of the GSM engine. Serves to
recognize whether a SIM card is in the holder.
Pins 1 through 8 (except for 5) are the minimum
requirement according to the GSM Recommendations,
where pins 7 and 8 are needed for SIM card tray
detection through the GSM_CCIN pin.
Figure 21: Pin numbers of Molex SIM card holder on DSB45
Support Box
Place the capacitors C1205 and C1206 (or instead one capacitor of 200nF) as close as
possible to the pins 1 (CCVCC) and 4 (GND) of the card holder. Connect the capacitors to
the pins via low resistance tracks.
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3.12
Control Signals
3.12.1
Inputs
Table 17: Input control signals of the GSM part of the XT55/56 module
Signal
Pin
Pin status
Function
Ignition
GSM_IGT
Falling edge
Power up XT55/56 Active low ≥ 100ms (Open
drain/collector driver to GND
No operation
required in cellular device
application).
Left open or HiZ
Remarks
Note: If a charger and a
battery is connected to the
customer application the
GSM_IGT signal must be 1s
minimum.
Emergency
shutdown
GSM_EMERG- Low
OFF
down Active low ≥ 3.2s
drain/collector
required in cellular
No operation
application).
At
GSM_EMERGOFF
the watchdog signal
GSM engine can be
(see description in
27).
Power
XT55/56
Left open or HiZ
(Open
driver
device
the
signal
of the
traced
Table
(HiZ = high impedance)
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3.12.2
Outputs
3.12.2.1
Synchronization Signal
The synchronization signal serves to indicate growing power consumption during the transmit
burst. The signal is generated by the GSM_SYNC pin. Please note that this pin can adopt
two different operating modes which you can select by using the AT^SSYNC command
(mode 0 and 1). For details refer to the following chapter and to [1].
To generate the synchronization signal the pin needs to be configured to mode 0 (= default).
This setting is recommended if you want your application to use the synchronization signal
for better power supply control. Your platform design must be such that the incoming signal
accommodates sufficient power supply to the XT55/56 module if required. This can be
achieved by lowering the current drawn from other components installed in your application.
The timing of the synchronization signal is shown below. High level of the GSM_SYNC pin
indicates increased power consumption during transmission.
1 Tx 577 µs every 4.616 ms
2 Tx 1154 µs every 4.616 ms
Transmit burst
GSM_SYNC signal*)
300 µs
Figure 22: GSM_SYNC signal during transmit burst
*)
The duration of the GSM_SYNC signal is always equal, no matter whether the traffic or
the access burst are active.
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3.12.2.2
Using the GSM_SYNC Pin to Control a Status LED
As an alternative to generating the synchronization signal, the SYNC pin can be used to
control a status LED on your application platform.
Especially in the development and test phase of an application, system integrators are
advised to use the LED mode of the SYNC pin in order to evaluate their product design and
identify the source of errors.
To avail of this feature you need to set the SYNC pin to mode 1 by using the AT^SSYNC
command. For details see [1].
Table 18: Coding of the status LED
LED mode
Operating status of XT55/56
Permanently off
XT55/56 is in one of the following modes:
• POWER DOWN mode
• ALARM mode
• CHARGE-ONLY mode
• NON-CYCLIC SLEEP mode
• CYCLIC SLEEP mode with no temporary wake-up event in
progress.
600 ms on / 600 ms off
Limited Network Service: No SIM card inserted or no PIN entered, or
network search in progress, or ongoing user authentication, or network
login in progress.
75 ms on / 3 s off
IDLE mode: The mobile is logged to the network (monitoring control
channels and user interactions). No call in progress.
75 ms on / 75 ms off /
75 ms on / 3 s off
One or more GPRS contexts activated.
0.5 s on / off depending on Packet switched data transfer in progress. LED goes on within
transmission activity
1 second after data packets were exchanged. Flash duration is
approximately 0.5 s.
75 ms
URC
Permanently on
Depending on type of call:
Voice call: Connected to remote party.
CSD call: Connected to remote party or exchange of parameters while
setting up or disconnecting a call.
LED Off = SYNC pin low. LED On = SYNC pin high (if LED is connected as illustrated in Figure 23)
Note: When a temporary wake-up event (URC, call, packet switched transfer) occurs in
CYCLIC SLEEP mode the LED flashes. See Table 11 for details on the various
SLEEP modes and wake-up events.
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To operate the LED a buffer, e.g. a transistor or gate,
must be included in your application. A sample
configuration can be gathered from Figure 23. Power
consumption in the LED mode is the same as for the
synchronization signal mode. For details see Table
27, GSM_SYNC pin.
Figure 23: LED Circuit (Example)
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3.12.3
Behavior of the GSM_RING0 Line (ASC0 Interface only)
The GSM_RING0 line is available on the first serial interface (ASC0). The signal serves to
indicate incoming calls and other types of URCs (Unsolicited Result Code).
Although not mandatory for use in a host application, it is strongly suggested that you
connect the GSM_RING0 line to an interrupt line of your application. In this case, the
application can be designed to receive an interrupt when a falling edge on GSM_RING0
occurs. This solution is most effective, particularly, for waking up an application from power
saving. Note that if the GSM_RING0 line is not wired, the application would be required to
permanently poll the data and status lines of the serial interface at the expense of a higher
current consumption. Therefore, utilizing the GSM_RING0 line provides an option to
significantly reduce the overall current consumption of your application.
The behavior of the GSM_RING0 line varies with the type of event:
• When a voice/fax/data call comes in the GSM_RING0 line goes low for 1s and high for
another 4s. Every 5 seconds the ring string is generated and sent over the GSM_RXD0
line.
If there is a call in progress and call waiting is activated for a connected handset or
handsfree device, the GSM_RING0 line switches to ground in order to generate acoustic
signals that indicate the waiting call.
4s
GSM_RING0
4s
1s
Ring
string
1s
Ring
string
1s
Ring
string
Figure 24: Incoming voice call
•
All other types of Unsolicited Result Codes (URCs) also
cause the GSM_RING0 line to go low, however for 1 second
only.
GSM_RING0
1s
URC
Figure 25: URC transmission
Table 19: ASC0 ring signal
Function
Pin
Status
Description
Ring indication
GSM_RING0
Indicates an incoming call or URC. If in NON-CYCLIC
SLEEP mode CFUN=0 or CYCLIC SLEEP mode
CFUN=5 or 6, the module is caused to wake up to full
functionality. If CFUN=7 or 8, power saving is resumed
after URC transmission or end of call.
No operation
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GPS Application Interface
The XT55/56 module integrates a GPS receiver which offers the full performance of GPS
technology. The GPS receiver continuously tracks all satellites in view, thus providing
accurate satellite position data.
The GPS block can be used even if the XT55/56 module is deregistered from the GSM
network.
4.1
Theory of Operation
Figure 26: Theory of operation
The XT55/56 GPS part is designed to use L1 Frequency (C/A Code) GPS receiver and
performs the entire GPS signal processing, from antenna input to serial position data output.
The processing steps involved are:
• RF section
In the RF section the GPS signal detected by the antenna is amplified, filtered and
converted to an intermediate frequency (IF). An A/D converter transforms the analogue
intermediate frequency into a digital IF signal.
• GPS channels
The received digital IF signal bit stream is passed to the baseband section, where it is fed
into the correlators. The function of the correlators is to acquire and track the satellite
signals. There are 12 channels used in parallel, with each correlator looking for a
characteristic PRN code sequence in the bit stream. Once the correlator has found a
valid signal, pseudo range, carrier phase and orbit information can be extracted from the
GPS signal.
• Navigation
The on-board processor is running an algorithm that calculates the position, velocity and
time. This calculation is called navigation solution. Once the navigation solution is
calculated, it can be transformed into the desired coordinate system, e.g. Latitude/
Longitude/ Altitude. For further details refer to [4].
• Interface
The data of the navigation solution are available at the serial RS-232 interface.
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4.2
Technical Data
Industry leading GPS performance
•
•
•
•
12 channel GPS receiver
Signal acquisition using 1920 time / frequency search channels
Multipath-mitigation hardware
Cold start < 45 sec
Low power
•
•
•
•
Typ. 220mW without active antenna (continuous mode)
TricklePower™ mode reduces power to < 60mW
Adaptive TricklePower™ switches between full and TricklePower™
Push-to-Fix reduces power by as much as 98%
Additional software options (can be obtained separately)
•
•
•
AVL (for further information refer to [4])
SiRFXtrac (high sensitivity stand alone software)
SiRFDrive (high sensitivity dead reckoning software)
Protocols
•
SDI1 / SDO1:
•
SDI2 / SDO2:
NMEA 9600 baud, Msg.: GLL, GGA, RMC, VTG, GSV, GSA, ZDA
8 data bits, no parity, 1 stop bit
RTCM, 9600 baud
Specification
•
•
•
1)
Position accuracy
Autonomous:
Beacon DGPS:
< 10 m
< 2.5 m
Receiver
Tracking:
Channels:
Max. update rate:
Sensitivity:
Max. altitude:
Max. velocity:
Protocol support:
L1, CA code
12
10 Hz
-142 dBm +2 dB 1)
<60.000 ft
<1.000 knots
NMEA, SiRF binary
Acquisition rate
SnapStart:
Hotstart:
Warmstart:
Coldstart:
< 3 sec
< 8 sec
< 38 sec
< 45 sec
The specified GPS receiver sensitivity of the XT55/56 (GPS software version 2.3) in
tracking mode is related to the ARP (antenna reference point). However, the applied
antenna, the antenna amplifier, the customer application and / or the applied reference
setup might cause variations of the stated receiver sensitivity value.
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4.3
GPS Operating Modes
Mode
Function
Normal operation
The receiver is continuously running in Normal mode, as long as the operating
voltage Vcc is supplied. Position fixes are generated at the maximum update
rate. This enables the receiver a warm- and hotstart. However, the cold- and
warmstart times of the receiver do not differ significantly under good visibility
conditions.
Trickle Power
mode
Vcc is continuously supplied to the receiver in Trickle Power mode. By using a
especially configurable software, the user can force the receiver to acquire a
position fix periodically. Between two fixes, the receiver will be in a low power
mode.
The power-on scenario in Trickle Power mode on the XT55/56 GPS part differs
from one in continuous mode. If the receiver fails to acquire satellites within a
given period of time (approx. 150 sec), the receiver enters an extended sleep
phase. The duration of this sleep phase is approx. 30 sec. After that, the
receiver wakes up, starts a reset and tries to acquire satellites. This procedure
will be repeated until the GPS receiver can detect satellites. For further details
refer to [1].
Push-to-Fix mode
In this mode the receiver will turn on every 30 minutes to perform a system
update consisting of a GPS RTC calibration and satellite ephemeris data
collection if required (i.e. a new satellite has become visible) as well as all
software tasks to support SnapSart in the event of an NMI. Ephemeris
collection time in general takes 18 to 30 seconds. If ephemeris data is not
required the system will recalibrate and shut down. In either case, the amount
of time the receiver remains off will be in proportion to how long it stayed on:
Off period = On Period*(1-Duty Cycle)
Duty Cycle
The off period has a possible range between 10 and 7200 seconds. The default
is 1800 seconds.
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4.3.1
Trickle Power Mode
The default mode of XT55/56 GPS part is continuous mode, but the user can set the
XT55/56 GPS part into the Trickle Power mode using the input command message. The
XT55/56 GPS part enters the Trickle Power mode corresponding to Figure 27 (800ms OFF
time and 200ms ON time) as soon as valid GPS data are available. As a result the average
power consumption is reduced by approximately 80 % (approximately 150mW). The settings
for the Trickle Power mode can be modified by using the SiRFstar demo software. For
example if the XT55/56 GPS part is configured to enter the OnTime mode each 10s for a
duration of 200ms the average power consumption can be reduced up to approx. 95%
(approx. 15mW, ca. 4.8mA at Vcc=3.3V). For more details refer to [1].
Figure 27: Example for current in Trickle Power mode
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4.3.2
Comparison of Trickle Power and Push-to-Fix Mode
A comparison of the Trickle Power mode and Push-to-Fix mode is shown in Figure 28. This
diagram shows that for position update intervals less than approximately 600 seconds (i.e.
rates faster than one fix per 10 minutes), the Trickle Power mode at an update interval of 10
seconds offers a lower power solution. The user would then be required to filter the output
position data to use only the data points corresponding to the desired update interval. For
example, if the desired position output is at 60 second intervals, then the user would only
need one out of every six position outputs at a 10 second Trickle Power update interval.
Alternatively, the user could perform smoothing or averaging of the position data and provide
an output at the desired rate.
Please note that neither Trickle Power mode nor Push-to-Fix mode are supported if running
XT55/56 AVL software. For further details regarding power supply ratings see [4].
Figure 28: Comparing typical current in Trickle Power and Push-to-Fix mode
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4.4
Power Supply of the XT55/56 GPS Part
The power supply for the GPS part of the XT55/56 module has to be a single voltage source
of VCC=3.3V ± 5%. It must be able to provide sufficient current of >100mA.
GPS_VCC:
Two GPS_VCC pins of the board-to-board connector are dedicated to connect the power
supply voltage, five GND pins shared with the GSM part of the XT55/56 module are
recommended for grounding; see Figure 40 for details.
If no GPS_VCC is connected to XT55/56, the RTC and SRAM of the GPS part of XT55/56
can be fed by GSM_BATT+ of XT55/56.
GPS_VANT:
This pin is used for an external DC power supply of an active antenna.
The GPS_VANT input voltage should be chosen according to the connected antenna.
In order to use a 5V active GPS antenna, the GPS_VANT has to be connected to 5V
external power supply.
When using a 3V antenna it is possible to connect the GPS_VCC_RF output (which provides
3.0V) to GPS_VANT.
GPS_VCC_RF:
This pin is an output which provides +3.0V DC and can be connected to the GPS_VANT in
order to supply the GPS antenna.
In Trickle Power mode and Push-to-Fix mode, GPS_VCC_RF is switched off during the
sleep phase.
GSM_BATT+:
If no GPS_VCC is connected to XT55/56, the RTC and SRAM of the GPS part of XT55/56 is
fed by GSM_BATT+ of XT55/56.
4.5
General Purpose Input/Output (GPIO)
Several I/O’s (GPS_GPIO0, GPS_GPIO1, GPS_GPIO3, GPS_GPIO5, GPS_GPIO6,
GPS_GPIO7, GPS_GPIO10, GPS_GPIO13, GPS_GPIO14, GPS_GPIO15) of the CPU are
connected to the hardware interface connector of the XT55/56 GPS receiver. They are
reserved for customer specific applications.
NOTE: Not all of these pins are supported by the current GPS firmware.
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4.6
Serial Interfaces of the XT55/56 GPS Part
The GPS part of the XT55/56 module offers two serial interfaces:
SD1
• 2-wire serial interface
• Includes the SDI1 (receive) and SDO1 (transmit) lines
• Supported baud rate: 9600…115200 bps. See also [1] for details on the used GPS
protocol.
SD2
• 2-wire serial interface
• Includes the SDI2 (receive) and SDO2 (transmit) lines. It is intended for communication
with the GSM/ GPRS part of the XT55/56 module. See Figure 2 for details.
• Supported baud rate: 9600…115200 bps. See also [1] for details on the used GPS
protocol.
SD1 and SD2
• Both interfaces are configured for 8 data bits, no parity and 1 stop bit
• For more detailed characteristics see [1]
4.7
GPS Control Signals
GPS_M-RST:
This pin provides an active-low reset input to the board. It causes the board
to reset and start searching for satellites. Reset is an optional input and, if
not utilized, it may be left open.
GPS_BOOTSEL:
Set this pin to high for reprogramming the flash of the XT55/56 GPS part (for
instance updating to a new XT55/56 GPS firmware).
GPS_RFPC0, GPS_RFPC1 (including pull-up resistors):
These pins are input pins for Trickle-Power mode control. To use the TricklePower mode function connect the RFPC0 and RFPC1 as shown in Figure
58. The pull-up resistors ensure the correct voltage level during start-up and
reset procedure of the GPS base band processor.
GPS_GPIO8, GPS_GPIO4:
These pins are control outputs for the Trickle-Power mode. GPS_GPIO8
must be connected to GPS_RFPC0 and GPS_GPIO4 to GPS_RFPC1.
GPS_GPIO8, GPS_GPIO4 can also be used to control a LED. A possible
circuit is shown in Figure 29. If the LED lights permanently the GPS receiver
is searching for satellites. If the GPS receiver is in Trickle-Power mode, the
LED flashes in rhythm, i.e. the GPS receiver receives valid position data.
Timing differs between GPS_GPIO4 and GPS_GPIO8.
Note: If Trickle power is switched off the LED lights permanently.
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Vcc = 3.3 V DC
330 Ω
GPS_RFPC0, GPS_RFPC1
BC817
47 k Ω
GND
Figure 29: Example of LED circuit
4.8
Receiver Architecture
The XT55/56 GPS receiver is a product that features the SiRFstarII-Low Power chipset. It is
a complete 12 channel, WAAS-enabled GPS receiver which provides a vastly superior
position accuracy performance. The SiRFstarII architecture builds on the high-performance
SiRFstarI core, adding an acquisition accelerator, differential GPS processor, multipath
mitigation hardware and satellite-tracking engine. The XT55/56 GPS receiver delivers major
advancements in GPS performance, accuracy, integration, computing power and flexibility.
BOOTSELECT
Antenna input
RECEIVER ARCHITECTURE
XTAL
RTC
LNA
RF
Filter
GRF2i/LP
RF
Front-End
GPS-Data
AGC
Clock
GSP2e/LP
Signal
Processor
2 x PWRCTL
(RFPC)
GPS_SDI 1
GPS_SDO 1
GPS_SDO 2
GPS_SDI 2
12 x GPS_GPIO
TCXO
Data Bus
Address Bus
GPS_VCC_RF
GPS_VANT
Reset IC
GPS_M-RST
GPS_VCC
(+3.3 V DC)
FLASH
1MByte
Figure 30: Receiver architecture of the GPS receiver
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Figure 30 above shows the block diagram of the XT55/56 GPS receiver architecture. The
GPS module can be separated into four major parts: RF frequency down-converter, digital
baseband demodulation, embedded ARM microprocessor and internal GPS software stored
on-board (1 MByte) Flash-Memory. The RF frequency conversion and the baseband
demodulation are executed by hardware while the embedded ARM processor computes the
GPS position, velocity and time solution employing the internal GPS software.
The purpose of the RF circuitry is to reinforce the very weak (-130dBm nominal) GPS signal,
to filter it and to down-convert it to an Intermediate Frequency (IF) of 9.45MHz for digital
processing. The SiRFstarII architecture relies on the high level of integration in the GRF2i to
significantly reduce part count and circuit complexity. A IF filter is built-in as well.
• The digital baseband demodulator takes the quantified GPS signal and detects the
individual satellites serial data bit stream, along with the associated pseudo range. This
action consists of removing spread spectrum and Doppler frequency components of the
signal to obtain the serial data messages.
• The embedded ARM processor monitors channel allocation, extracts the raw satellite
tracking data, computes the position and time solution and sends it on a serial port for
high level applications to use or processes it locally. Support functions for the
microprocessor include real time clock and reset pulse generator circuits. The internal
GPS software monitors and allocates channels, computers the position, velocity and time
using the pseudo-range of the satellites and reformats the data to be output or used
locally. The internal GPS software is a tasking based architecture driven by the 100ms
interrupt generated by GPS2e internal hardware.
4.9
Operation Procedure
When the receiver is powered up, it steps trough a sequence of states until it can initially
determine position, velocity and time. Afterwards, the satellite signals are tracked
continuously and the position is calculated periodically.
In order to perform a navigation solution (3D solution), the receiver needs.
•
•
Pseudo-ranges for at least 3 satellites
Ephemeris data for the satellites it will use in the navigation solution.
Note: If almanac navigation is enabled, the receiver can calculate a position without
downloading ephemeris data (with a significant position error compared to an
ephemeris based solution).
The initial position calculation is made, using a Least-Squares Algorithm. Successive position
calculations are performed with a Kalman Filter. To generate a position (3D solution)
calculation the receiver needs at least 4 measurements to different satellites. In order to
calculate a position (Latitude/Longitude/Height), as a 2D solution with an estimated height
value, then 3 different satellites are required. Pseudo-range and carrier phase information
are available to the position determination algorithms if the receiver has found a SV
(acquisition) and can track the signal thereafter. Ephemeris data for a SV can be decoded
from orbit data once the GPS signal has been acquired. Each SV transmits its own
ephemeris data, the broadcast lasts for 18 seconds, repeating every 30 seconds.
The receiver stores ephemeris data in battery-backed memory. This data can be used in
future startup’s to improve the time to first fix (TTFF). The ephemeris can also be supplied to
the receiver via the serial port.
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4.10
Start-up Procedures
The start-up strategy of the XT55/56 GPS part depends on the last position, current time and
ephemeris data, that the receiver has stored the external SRAM memory. There are three
different start-up procedures:
4.10.1
Coldstart
The coldstart takes place when the receiver has no knowledge of its last position or time. In
this case the GPS RTC has not been running and no valid ephemeris data or almanac data
is available (The receiver has never been navigating or no battery backup memory
available).
4.10.2
Warmstart
This start-up procedure is performed whenever the receiver is able to use the valid almanac
data, and has not in an important manner moved since the last valid position calculation. This
procedure starts if the receiver has been shut off for more than 2 hours, but the last position,
time and almanac are still acknowledged. This procedure is able to announce the current
visible satellites in advance. However, since ephemeris data are not available or cannot
longer be used, the receiver has to wait for the ephemeris broadcast to complete.
4.10.3
Hotstart
Hotstart is performed whenever the receiver still has access to valid ephemeris data and
exact time. This procedure starts if the receiver has been shut off for less than 2 hours and
the GPS RTC has been running during that time. Furthermore, during the previous session,
the receiver must have been navigating (to allow it to decode and store ephemeris data).
In Hotstart, the receiver can announce in advance the currently visible satellites, and is
therefore able to quickly obtain and track the signal. Due to the fact that ephemeris is already
known, there is no need to wait for the ephemeris broadcast to complete.
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GSM and GPS Antenna Interfaces
5.1
GSM Antenna Installation
The RF interface has an impedance of 50Ω. XT55/56 is capable of sustaining a total
mismatch at the antenna connector or pad without any damage, even when transmitting at
maximum RF power.
The external antenna must be matched properly to achieve best performance regarding
radiated power, DC-power consumption and harmonic suppression. Matching networks are
not included on the XT55/56 PCB and should be placed in the host application.
Regarding the return loss XT55/56 provides the following values:
Table 20: Return loss
State of module
Return loss of module
Recommended return loss of application
Receive
> 8dB
> 12dB
Transmit
not applicable
> 12dB
Idle
< 5dB
not applicable
The connection of the antenna or other equipment must be decoupled from DC voltage.
5.1.1
GSM antenna Connector
To suit the physical design of individual applications XT55/56 offers two alternative
approaches to connecting the GSM antenna:
• Recommended approach: U.FL-R-SMT antenna connector from Hirose assembled on
the component side of the PCB (top view on XT55/56). See Chapter 5.3 for details.
• Antenna pad and grounding plane placed on the bottom side. See Chapter 5.1.2.
Antenna ground
Antenna pad
Figure 31: U.FL-R-SMT connector
Figure 32: Antenna pad and GND plane
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The U.FL-R-SMT connector has been chosen as antenna reference point (ARP) for the
Siemens reference equipment submitted to type approve XT55/56. All RF data specified
throughout this manual are related to the ARP. For compliance with the test results of the
Siemens type approval you are advised to give priority to the connector, rather than using the
antenna pad.
IMPORTANT: Both solutions can only be applied alternatively. This means, whenever an
antenna is plugged to the Hirose connector, the pad must not be used. Vice versa, if the
antenna is connected to the pad, then the Hirose connector must be left empty.
Antenna connected to Hirose connector:
Module
PAD
U.FL
Antenna connected to pad:
Antenna or
measurement
equipment
PAD
U.FL
50Ohm
50Ohm
50Ohm
Module
Antenna or
measurement
equipment
50Ohm
Figure 33: Never use antenna connector and antenna pad at the same time
No matter which option you choose, ensure that the antenna pad does not come into contact
with the holding device or any other components of the host application. It needs to be
surrounded by a restricted area filled with air, which must also be reserved 0.8 mm in height.
U.FL antenna connector
RF section
PCB
Antenna pad
Restricted area
Figure 34: Restricted area around antenna pad
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5.1.2
GSM Antenna Pad
The antenna can be soldered to the pad, or attached via contact springs. To help you ground
the antenna, XT55/56 comes with a grounding plane located close to the antenna pad. The
positions of both pads can be seen from Figure 50.
When you decide to use the antenna pad take into account that the pad has not been
intended as antenna reference point (ARP) for the Siemens XT55/56 type approval. The
antenna pad is provided only as an alternative option which can be used, for example, if the
recommended Hirose connection does not fit into your antenna design.
Also, consider that according to the GSM recommendations TS 45.005 and TS 51.010-01 a
50Ω connector is mandatory for type approval measurements. This requires GSM devices
with an integral antenna to be temporarily equipped with a suitable connector or a low loss
RF cable with adapter.
To prevent damage to the module and to obtain long-term solder joint properties you are
advised to maintain the standards of good engineering practice for soldering.
XT55/56 material properties:
XT55/56 PCB:
FR4
Antenna pad:
Gold plated pad
Suitable cable types:
For direct solder attachment, we suggest to use the following cable types:
• RG316/U 50 Ohm coaxial cable
• 1671A 50 Ohm coaxial cable
Suitable cables are offered, for example, by IMS Connector Systems. For further details and
other cable types please contact http://www.imscs.com.
5.2
Installing the GPS Antenna
In order to receive satellite signals an additional GPS antenna must be connected to the
GPS part of the XT55/56 module. The position of the GPS antenna connector can be found
in Figure 35 and Figure 51. Recommended devices which can be mounted onto the Hirose
connector are available in Chapter 10.
Figure 35: GPS antenna connector (U.FL-R-SMT connector)
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5.3
Hirose Antenna Connector
XT55/56 uses two ultra-miniature SMT antenna connectors (GSM
and GPS antenna) supplied from Hirose Ltd. The product name is
U.FL-R-SMT.
The positions of both antenna connectors on the XT55/56 board
can be seen in Figure 49.
Figure 36: Mechanical dimensions of U.FL-R-SMT connector
Table 21: Product specifications of U.FL-R-SMT connector
Item
Specification
Conditions
Nominal impedance
50 Ω
Rated frequency
DC to 6 GHz
Operating temp: -40°C to +90°C
Operating humidity: max. 90%
Ratings
Mechanical characteristics
Female contact holding
force
0.15 N min
Measured with a ∅ 0.475 pin
gauge
Repetitive operation
Contact resistance:
Centre 25 mΩ
Outside 15mΩ
30 cycles of insertion and
disengagement
Vibration
No momentary disconnections of
1 µs;
No damage, cracks and looseness
of parts
Frequency of 10 to 100 Hz,
single amplitude of 1.5 mm,
acceleration of 59 m/s2, for 5
cycles in the direction of each of
the 3 axes
Shock
No momentary disconnections of
Acceleration of 735 m/s2, 11 ms
1 µs.
duration for 6 cycles in the
No damage, cracks and looseness direction of each of the 3 axes
of parts.
Environmental characteristics
Humidity resistance
No damage, cracks and looseness Exposure to 40°C, humidity of
of parts.
95% for a total of 96 hours
Insulation resistance:
100 MΩ min. at high humidity
500 MΩ min when dry
Temperature cycle
No damage, cracks and looseness
of parts.
Contact resistance:
Centre 25 mΩ
Outside 15mΩ
Temperature: +40°C → 5 to 35°C
→ +90°C → 5 to 35°C
Time: 30 min. → within 5 min. →
30 min. → within 5 min
Salt spray test
No excessive corrosion
48 hours continuous exposure to
5% salt water
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Table 22: Material and finish of U.FL-R-SMT connector and recommended plugs
Part
Material
Finish
Shell
Phosphor bronze
Silver plating
Male centre contact
Brass
Gold plating
Female centre contact
Phosphor bronze
Gold plating
Insulator
Plug:
Receptacle:
PBT
LCP
Black
Beige
Mating plugs and cables can be chosen from the Hirose U.FL Series. Examples are shown
below and listed in Table 23. For latest product information please contact your Hirose dealer
or visit the Hirose home page, for example http://www.hirose.com.
Figure 37: U.FL-R-SMT connector with U.FL-LP-040 plug
Figure 38: U.FL-R-SMT connector with U.FL-LP-066 plug
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In addition to the connectors illustrated above, the U.FL-LP-(V)-040(01) version is offered as
an extremely space saving solution. This plug is intended for use with extra fine cable (up to
∅ 0.81 mm) and minimizes the mating height to 2 mm. See Figure 39 which shows the
Hirose datasheet.
Figure 39: Specifications of U.FL-LP-(V)-040(01) plug
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Table 23: Ordering information for Hirose U.FL Series
Item
Part number
HRS number
Connector on XT55/56
U.FL-R-SMT
CL331-0471-0-10
Right-angle plug shell for
∅ 0.81 mm cable
U.FL-LP-040
CL331-0451-2
Right-angle plug for
∅ 0.81 mm cable
U.FL-LP(V)-040 (01)
CL331-053-8-01
Right-angle plug for
∅ 1.13 mm cable
U.FL-LP-068
CL331-0452-5
Right-angle plug for
∅ 1.32 mm cable
U.FL-LP-066
CL331-0452-5
Extraction jig
E.FL-LP-N
CL331-0441-9
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Electrical, Reliability and Radio Characteristics
6.1
Absolute Maximum Ratings
Absolute maximum ratings for supply voltage and voltages on digital and analog pins of
XT55/56 are listed in Table 24. Exceeding these values will cause permanent damage to
XT55/56.
Table 24: Absolute maximum ratings (GSM part)
Parameter
Min
Max
Unit
Voltage GSM_BATT+
-0.3
4.8
Voltage at digital pins
-0.3
3.3
Voltage at analog pins
-0.3
3.0
Voltage at digital / analog pins in POWER DOWN mode
-0.25
+0.25
Voltage at GSM_POWER pin
15
Voltage at GSM_CHARGE pin
15
Differential load resistance between EPNx and EPPx
Ω
15
Table 25: Absolute maximum rating (GPS part)
Parameter
Min
Max
Unit
Voltage at GPS_VCC
-0.3
3.46
25
mA
Current at GPS_VCC_RF
6.2
Operating Temperatures
Test conditions were specified in accordance with IEC 60068-2 (still air). The values stated
below are in compliance with GSM recommendation TS 51.010-01.
Table 26: Operating temperatures
Parameter
Ambient temperature (according to GSM 11.10)
*)
Restricted operation
Min
Typ
Max
-20
25
55
Unit
°C
***
-25 to -20
55 to 70
°C
-29
-18
>70**
>60
°C
°C
+45
°C
Automatic shutdown
XT55/56 board temperature
Battery temperature
Charging temperature (software controlled fast charging)
*)
XT55/56 works, but deviations from the GSM specification may occur.
**)
XT55/56 has the automatic shutdown set to 70°C at PCL 5 (GSM 900) GPRS class 8. This
prevents permanent damage to components on the board. Consider the ratio of output power,
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supply voltage and operating temperature: To achieve Tamb max = 70°C and, for example, GSM
900 PCL 5 the supply voltage must not be higher than 4.2V.
***)
To achive Tamb max = 70°C at permanent GPRS class 8 operation (1 TX, 4 RX GSM 900 at
PCL 5 with a supply voltage 4.2V) it is recommended to integrate XT55/56 in such a way that a
minor heat exchange with the environment can take place. A solution might be the usage of a
small heat sink.
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6.3
Pin Description
Please note that the reference voltages listed in Table 27 are the values measured directly
on the XT55/56 module. They do not apply to the accessories connected.
If an input pin is specified for VIHmax = 3.3V, be sure never to exceed the stated voltage. The
value 3.3V is an absolute maximum rating.
The Hirose DF12C board-to-board connector on XT55/56 is a 80-pin double-row receptacle.
The names and the positions of the pins can be seen from Figure 40 which shows the top
view of XT55/56.
GPS_VANT
80
GSM_EPN2
GPS_VCC_RF
79
GSM_EPP2
GPS_VCC
78
GSM_EPP1
GPS_VCC
77
GSM_EPN1
GSM_RXDDAI
76
GSM_MICN2
GSM_TFSDAI
75
GSM_MICP2
GSM_SCLK
74
GSM_MICP1
GSM_TXDDAI
73
GSM_MICN1
GSM_RFSDAI
72
GSM_CCVCC
NC
10
71
GSM_CCCLK
NC
11
70
GSM_CCIO
NC
12
69
GSM_CCRST
NC
13
68
GSM_CCIN
NC
14
67
GSM_CCGND
GSM_RTS1
15
66
GSM_IGT
GSM_CTS1
16
65
GSM_EMERGOFF
GSM_RXD1
17
64
GSM_DCD0
GSM_TXD1
18
63
GSM_CTS0
NC
19
62
GSM_DTR0
GPS_GPIO15
20
61
GSM_RTS0
GPS_GPIO14
21
60
GSM_RING0
GPS_GPIO13
22
59
GSM_DSR0
GPS_GPIO10
23
58
GSM_TXDO
GPS_GPIO9
24
57
GSM_RXDO
GPS_GPIO8
25
56
GPS_SDI2
GPS_GPIO7
26
55
GPS_SDO2
GPS_GPIO6
27
54
GSM_CHARGE
GPS_GPIO5
28
53
GSM_POWER
GPS_GPIO4
29
52
GSM_BATT_TEMP
GPS_GPIO3
30
51
GSM_SYNC
GPS_GPIO1
31
50
GSM_BATT+
GPS_GPIO0
32
49
GSM_BATT+
GPS_SDI1
33
48
GSM_BATT+
GPS_SDO1
34
47
GSM_BATT+
GPS_BOOTSEL
35
46
GSM_BATT+
GPS_RFPCO
36
45
GND
GPS_RFPC1
37
44
GND
GPS_M-RST
38
43
GND
GSM_VDD
39
42
GND
GSM_VDDLP
40
41
GND
Figure 40: Pin assignment (top view on XT55/56)
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Table 27: Electrical description of application interface
Function
Signal name
IO
Signal form and level
Comments
GSM power
supply
GSM_BATT+
VI = 3.3V to 4.8V
VInorm = 4.2V
Inorm ≈ 1.6A (during Tx burst)
Imax< 2A
Power supply input.
5 GSM_BATT+ pins to be
connected in parallel. 5 GND
pins to be connected in
parallel.
The power supply must be
able to meet the
requirements of current
consumption in a Tx burst
(up to 3A).
Sending with two timeslots
doubles the duration of
current pulses to 1154µs
(every 4.616ms)!
GND
1 Tx, peak current 577µs every 4.616ms
2 Tx, peak current 1154µs every
4.616ms
Charge
interface
This line signalizes to the
processor that the charger is
connected.
If unused keep pin open.
GSM_POWER
GSM_BATT_TEM
GSM_CHARGE
IGSM_CHARGE = -300µA ... -600µA
@ 3V < VGSM_CHARGE < VLOAD
This line is a current source
for the charge FET with a
10kΩ resistance between
gate and source.
If unused keep pin open.
External
supply
voltage
GSM_VDD
GSM_VDDmin = 2.84V,
GSM_VDDmax = 2.96V
Imax = -10mA
CLmax = 1µF
Supply voltage, e.g. for an
external LED or level shifter.
The external digital logic
must not cause any spikes or
glitches on voltage
GSM_VDD.
Not available in POWER
DOWN mode.
GSM_VDD signalizes the
“ON” state of the module.
If unused GSM_VDD keep
pin open.
VDD Low
Power
GSM_VDDLP
I/O
RI =1kΩ
VOmax ≈ 4.0V (output)
Supplies the RTC with power
via an external capacitor or
buffer battery if no VGSM_BATT+
is applied.
If unused keep pin open.
VImin = 3.0V
VImax = 15V
Connect NTC with RNTC ≈ 10kΩ @ 25°C
to ground.
VImin = 2.2V, VImax = 5.5V (input)
IItyp = 10µA at GSM_BATT+ = 0V
Mobile in POWER DOWN mode:
VImin = 1.2V
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Input to measure the battery
temperature over NTC
resistor.
NTC should be installed
inside or near battery pack to
enable the charging
algorithm and deliver
temperature values.
If unused keep pin open.
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Function
Signal name
IO
Signal form and level
Comments
Ignition
GSM_IGT
RI ≈ 100kΩ, CI ≈ 1nF
VILmax = 0.5V at Imax = -20µA
VOpenmax = 2.3V
Input to switch the mobile
ON.
The line must be driven low
by an Open Drain or Open
Collector driver.
ON
Emergency
shutdown
(Watchdog)
GSM_EMERGOFF I/O
~~~
|____|~~~ Active Low ≥ 100ms
RI ≈22kΩ
VILmax = 0.5V at Imax = -100µA
VOpenmax = 2.73V
Signal
3.2s
~~~
|______|~~~ Active Low ≥
Watchdog:
VOLmax = 0.35V at I = 10µA
VOHmin= 2.25V at I = -10µA
fOmin = 0.16Hz
fOmax = 1.55Hz
This line must be driven by
an Open Drain or Open
Collector driver.
Emergency shutdown
deactivates the power supply
to the module.
The module can be reset if
GSM_IGT is activated after
emergency shutdown.
To switch the mobile off use
the AT^SMSO command.
To avoid floating if pin is high
impedance, use pull-down
resistor tied to GND. See
Chapter 3.3.2.1.
GSM_EMERGOFF also
indicates the internal
watchdog function.
If unused keep pin open.
Synchronization
GSM_SYNC
VOLmax = 0.2V at I = 1mA
VOHmin = 2.35V at I = -1mA
VOHmax = 2.73V
Indicates increased current
consumption during uplink
transmission burst. Note that
timing is different during
handover.
Alternatively used to control
status LED (see Chapter
3.12.2.2).
If unused keep pin open.
1 Tx, 877µs impulse each 4.616ms and
2 Tx, 1454µs impulse each 4.616ms,
with 300µs forward time.
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Function
Signal name
IO
Signal form and level
Comments
RI ≈ 100kΩ
VILmax = 0.5V
VIHmin = 2.15V at I = 20µA,
VIHmax=3.3V at I = 30µA
GSM_CCIN = high, SIM
card holder closed (no card
recognition)
GSM_CCRST
RO ≈47Ω
VOLmax = 0.25V at I = 1mA
VOHmin = 2.3V at I = -1mA
VOHmax = 2.73V
GSM_CCIO
IO
RI ≈10kΩ
VILmax = 0.5V
VIHmin = 1.95V, VIHmax=3.3V
Maximum cable length
200mm to SIM card holder.
All signals of SIM interface
are protected against ESD
with a special diode array.
Usage of GSM_CCGND is
mandatory.
SIM interface GSM_CCIN
RO ≈220Ω
VOLmax = 0.4V at I = 1mA
VOHmin = 2.15V at I = -1mA
VOHmin = 2.55V at I = -20µA
VOHmax = 2.96V
GSM_CCCLK
RO ≈220Ω
VOLmax = 0.4V at I = 1mA
VOHmin = 2.15V at I = -1mA
VOHmax = 2.73V
GSM_CCVCC
ROmax = 5Ω
GSM_CCVCCmin = 2.84V,
GSM_CCVCCmax = 2.96V
Imax = -20mA
GSM_CCGND
ASC0
interface
ASC1
interface
Ground
GSM_RXD0
GSM_TXD0
GSM_CTS0
GSM_RTS0
GSM_DTR0
GSM_DCD0
GSM_DSR0
GSM_RING0
GSM_RXD1
GSM_TXD1
GSM_CTS1
GSM_RTS1
VOLmax = 0.2V at I = 1mA
VOHmin = 2.35V at I = -1mA
VOHmax = 2.73V
VILmax = 0.5V
VIHmin = 1.95V, VIHmax=3.3V
GSM_DTR0, GSM_RTS0: Imax = -90µA
at VIN = 0V
GSM_TXD0: Imax = -30µA at VIN = 0V
VOLmax = 0.2V at I = 1mA
VOHmin = 2.35V at I = -1mA
VOHmax = 2.73V
VILmax = 0.5V
VIHmin = 1.95V, VIHmax=3.3V
IImax = -90µA at VIN = 0V
First serial interface for AT
commands or data stream.
To avoid floating if output
pins are high-impedance,
use pull-up resistors tied to
GSM_VDD or pull-down
resistors tied to GND. See
Chapter 3.3.2.1.
If unused keep pins open.
Second serial interface for
AT commands.
To avoid floating if output
pins are high-impedance,
use pull-up resistors tied to
GSM_VDD or pull-down
resistors tied to GND. See
Chapter 3.3.2.1.
If unused keep pins open.
Digital audio
interface
GSM_RFSDAI
GSM_RXDDAI
GSM_SCLK
GSM_TFSDAI
GSM_TXDDAI
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VOLmax = 0.2V at I = 1mA
VOHmin = 2.35V at I = -1mA
VOHmax = 2.73V
If unused keep pins open.
VILmax = 0.5V
VIHmin = 1.95V, VIHmax=3.3V
IImax = 330µA at VIN = 3.3V
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Signal name
IO
Signal form and level
Comments
VOmax = 3.7Vpp
See also Table 32.
The audio output is
balanced and can directly
operate an earpiece.
If unused keep pins open.
VOmax = 3.7Vpp
See also Table 32.
Balanced audio output. Can
be used to directly operate
an earpiece.
If unused keep pins open.
RI ≈ 50kΩ differential
VImax = 1.03Vpp
See also Table 33.
Balanced microphone input.
To be decoupled with 2
capacitors (CK = 100nF), if
connected to a microphone
or another device.
If unused keep pins open.
RI = 2kΩ differential
VImax = 1.03Vpp
See also Table 33.
Balanced microphone input.
Can be used to directly feed
an active microphone.
If used for another signal
source, e.g. op amp, to be
decoupled with capacitors.
If unused keep pins open.
Max. 8V DC
Max. 25 mA
Power supply for active
antenna; in case of 3V
antenna can be connected
to GPS_VCC_RF
GPS_VCC_RF
Typ.: 3.0V ±5% DC
Max: 25 mA
Regulates 3V output for
feeding a 3V active GPS
antenna
GPS_VCC
Typ.: 3.3V ±5% DC
Typ. 80 mA (without feeding
GPS_VCC_RF)
50 mV ripple
Digital Input / GPS_GPIO0
Output
I/O
CMOS 3.3V DC level
See Chapter 4.5
Digital Input / GPS_GPIO1
Output
I/O
CMOS 3.3V DC level
See Chapter 4.5
Digital Input / GPS_GPIO3
Output
I/O
CMOS 3.3V DC level
See Chapter 4.5
Digital Input / GPS_GPIO4
Output
I/O
CMOS 3.3V DC level
Output for Trickle Power
mode. Connect externally to
GPS_RFPC1. Usable as
LED control output, see
Chapter 4.7
Digital Input / GPS_GPIO5
Output
I/O
CMOS 3.3V DC level
See Chapter 4.5
Digital Input / GPS_GPIO6
Output
I/O
CMOS 3.3V DC level
See Chapter 4.5
Digital Input / GPS_GPIO7
Output
I/O
CMOS 3.3V DC level
See Chapter 4.5
Digital Input / GPS_GPIO8
Output
I/O
CMOS 3.3V DC level
Output for Trickle Power
mode. Connect externally to
GPS_RFPC0. Usable as
LED control output, see
Chapter 4.7
Digital Input / GPS_GPIO10
Output
I/O
CMOS 3.3V DC level
See Chapter 4.5
Digital Input / GPS_GPIO13
Output
I/O
CMOS 3.3V DC level
See Chapter 4.5
Analog audio GSM_EPP2
interfaces
GSM_EPN2
GSM_EPP1
Explanation of signal names:
P = positive, N = negative
Function
GSM_EPN1
GSM_MICP1
GSM_MICN1
GSM_MICP2
GSM_MICN2
Antenna
power
GPS_VANT
Internal
antenna
power
GPS power
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Function
IO
Signal form and level
Comments
Digital Input / GPS_GPIO14
Output
Signal name
I/O
CMOS 3.3V DC level
See Chapter 4.5
Digital Input / GPS_GPIO15
Output
I/O
CMOS 3.3V DC level
See Chapter 4.5
GPS Reset
GPS_M-RST
CMOS 3.3V DC level
Active low reset input
Serial1 Rx
GPS_SDI1
CMOS 3.3V DC level
See Chapter 4.6
Serial1 Tx
GPS_SDO1
CMOS 3.3V DC level
See Chapter 4.6
Digital Input
GPS_BOOTSEL
CMOS 3.3V DC level
For re-programming the
Flash must be set to High
Digital Input
GPS_RFPC1
CMOS 3.3V DC level
Connect to GPS_GPIO4
including the pull-up
resistors as shown in Figure
58
Digital Input
GPS_RFPC0
CMOS 3.3V DC level
Connect to GPS_GPIO8
including the pull-up
resistors as shown in Figure
58
Serial2 Rx
GPS_SDI2
CMOS 3.3V DC level
See Chapter 4.6
Serial2 Tx
GPS_SDO2
CMOS 3.3V DC level
See Chapter 4.6
CMOS 3.3V level:
XT55/56_hd_v02.96
Input High
Input Low
2.0 – 3.3
0 – 0.8
V DC; I_leakage = 2µA
V DC, I_leakage = 2µA
Output High
Output Low
min. 2.4
max 0.4
V DC, Ioh= 2mA
V DC, Ioh= 2mA
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6.4
Power Supply Ratings
Table 28: Power supply ratings (GSM part)
Parameter
Description
Conditions
Min
GSM_BATT+
Supply voltage
Reference points on XT55/56:
TP GSM_BATT+ and TP GND (see
Figure 50).
3.3
Typ
Max
4.2
Unit
4.8
400
mV
Voltage must stay within the
min/max values, including voltage
drop, ripple, spikes.
Voltage drop
during transmit
burst
Normal condition, power control
level for Pout max
Voltage ripple
Normal condition, power control
level for Pout max
@ f<200kHz
50
@ f>200kHz
IGSM_BATT+
Average supply
current3)
POWER DOWN mode
50
SLEEP mode
@ DRX = 6
IDLE mode
TALK mode
µA
mA
GSM850
15
mA
EGSM 900
15
GSM 1800/1900
15
1) 4)
GSM850
260
EGSM 900
260
GSM 1800/19002) 4)
180
GSM850
15
EGSM 900
15
GSM 1800/1900
15
DATA mode GPRS,
(4 Rx, 1 Tx)
GSM 8501) 4)
EGSM 900
mA
mA
300
2) 4)
GSM 1800/1900
DATA mode GPRS,
(3 Rx, 2 Tx)
GSM 8501) 4)
230
450
1) 4)
EGSM 900
mA
450
2) 4)
GSM 1800/1900
Power control level
mA
300
1) 4)
Peak supply
current (during
transmission slot
every 4.6ms)
100
1) 4)
IDLE GPRS
mV
1)
330
1.6
1)
Power control level PCL 5
2)
Power control level PCL 0
3)
All average supply current values @ IGSM_VDD = 0mA
4)
Test conditions: 50Ω
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Table 29: Power supply ratings (GPS part)
Parameter Description
Conditions
GPS_VCC Supply voltage
IGPS_VCC
Average supply
current
Min
3.14
Continuous mode (without antenna
feeding on GPS_VCC_RF)
Typ
Max
Unit
3.3
3.46
80
100
mA
Please note that the stated current values are depending on the used mode of the module
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6.4.1
Current Consumption during GSM Transmit Burst
The diagrams provided in Figure 46 and Figure 47 illustrate the typical current consumption
of the application caused during a transmit burst. The typical peak current is shown vs. the
power control level for 900 MHz, 1800 MHz and 1900 MHz and vs. the return loss of the
antenna.
Test conditions: All measurements have been performed at Tamb= 25°C, VGSM_BATT+ nom = 4.1V.
Reference points for measuring the voltage are the GSM_BATT+ and GND test points on the
back side of the module. The curves are for one TX slot (for example a voice call, CSD call
or Class 8 GPRS). Curves for Class 10 GPRS activities (2 TX slots) are shown too.
Changing the conditions, e.g. in terms of temperature or voltage, will cause different results.
Average Current GSM900 (VBATT+=4.1V)
0.5
0.45
0.4 0.43
1 TX - Average Current
2 TX - Average Current
Current (Amps)
0.35
0.33
0.3
0.25
0.25
0.23
0.2
0.21
0.15
0.16
0.15
0.1
0.11
0.14
0.13
0.10
0.10
0.05
11
13
15
17
19
Power Control Level
Figure 41: Typical current consumption vs. return loss in EGSM 900 network
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Average Current DCS1800 (VBATT+=4.1V)
0.3
0.25
0.26
1 TX - Average Current
2 TX - Average Current
Current (Amps)
0.2
0.19
0.15
0.18
0.16
0.14
0.13
0.13
0.1
0.12
0.10
0.10
0.05
10
11
12
13
14
15
Power Control Level
Figure 42: Typical current consumption vs. return loss in GSM 1800 network
Average Current PCS1900 (VBATT+=4.1V)
0.3
0.29
0.25
1 TX - Average Current
2 TX - Average Current
Current (Amps)
0.2
0.15
0.21
0.17
0.17
0.14
0.13
0.13
0.12
0.1
0.11
0.10
0.05
10
11
12
13
14
Power Control Level
Figure 43: Typical current consumption vs. return loss in GSM 1900 network
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Burst Current GSM900 (VBATT+=4.1V)
1.8
1.6
1.6
1.4
1 TX - Peak current
1.2
Current (Amps)
1.24
0.8
0.6
0.68
0.4
0.4
0.3
0.2
0.28
11
13
15
17
19
Power Control Level
Figure 44: Peak current consumption during transmit burst in EGSM 900 network
Burst Current DCS1800 (VBATT+=4.1V)
0.9
0.8
1 TX - Peak current
0.84
Current (Amps)
0.7
0.6
0.5
0.52
0.4
0.38
0.3
0.27
0.2
0.24
0.1
10
11
12
13
14
15
Power Control Level
Figure 45: Peak current consumption during transmit burst in GSM 1800 network
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Burst Current PCS1900 (VBATT+=4.1V)
0.92
0.9
0.8
1 TX - Peak current
Current (Amps)
0.7
0.6
0.6
0.5
0.4
0.42
0.3
0.3
0.24
0.2
0.1
10
11
12
13
14
15
Power Control Level
Test conditions: Tamb= 25°C, VGSM_BATT+ nom = 4.1V
Figure 46: Peak current consumption during transmit burst in GSM 1900 network
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1600
Service mode GSM900 ch.124
Variations in current with 0.4dB return
loss (all phases)
1400
1200
Current (mA)
1000
ch.124 PCL5
800
600
400
200
Burst (max)
Burst (min)
Average Current (Max)
Average Current (Min)
1000
Service mode PCS1900 ch.661
Variations in current with 0.6dB return
loss (all phases)
900
800
700
Current (mA)
600
ch.661 PCL0
500
400
300
200
100
Burst (max)
Burst (min)
Average Current (Max)
Average Current (Min)
Test conditions: Tamb= 25°C, VGSM_BATT+ nom = 4.1V measured at TP GSM_BATT+ and GND, 1 TX slot
Figure 47: Typical current consumption vs. return loss
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6.5
Electrical Characteristics of the Voiceband Part
6.5.1
Setting Audio Parameters by AT Commands
The audio modes 2 to 6 can be adjusted according to the parameters listed below. Each
audio mode is assigned a separate set of parameters.
Table 30: Audio parameters adjustable by AT command
Parameter
Influence to
Range
Gain range
Calculation
inBbcGain
MICP/MICN analog amplifier gain of
baseband controller before ADC
0...7
0...42dB
6dB steps
inCalibrate
digital attenuation of input signal
after ADC
0...32767 -∞...0dB
20 * log
(inCalibrate/
32768)
outBbcGain
EPP/EPN analog output gain of
baseband controller after DAC
0...3
6dB steps
outCalibrate[n]
n = 0...4
digital attenuation of output signal
after speech decoder, before
summation of sidetone and DAC
0...32767 -∞...+6dB
20 * log (2 *
outCalibrate[n]/
32768)
0...32767 -∞...0dB
20 * log
(sideTone/
32768)
0...-18dB
present for each volume step[n]
sideTone
digital attenuation of sidetone
is corrected internally by
outBbcGain to obtain a constant
sidetone independent of output
volume
Note: The parameters inCalibrate, outCalibrate and sideTone accept also values from 32768
to 65535. These values are internally truncated to 32767.
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6.5.2
Audio Programming Model
The audio programming model shows how the signal path can be influenced by varying the
AT command parameters. The model is the same for all three interfaces, except for the
parameters  and  which cannot be modified if the digital audio
interface is being used, since in this case the DAC is switched off.
The parameters inBbcGain and inCalibrate can be set with AT^SNFI. All the other
parameters are adjusted with AT^SNFO.
GSM_MIC1

2.65V
1k

1k
GSM_MIC2
-∞...0dB
10uF
1k

Speech coder
+0...42dB in 6dB steps
1k
GSM_RFSDAI, GSM_RXDDAI




Speech decoder

neg. gain (attenuation)
0dB; -6db, -12dB; -18dB
n = 0...4
AT parameters are given in brackets <…>
and marked red and italic.
GSM_TFSDAI, GSM_TXDDAI
Figure 48: AT audio programming model
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6.5.3
Characteristics of Audio Modes
The electrical characteristics of the voiceband part depend on the current audio mode set
with the AT^SNFS command.
Table 31: Voiceband characteristics (typical)
Audio mode no.
AT^SNFS=
1 (Default
settings, not
adjustable)
Name
Default
Handset
Basic
Handsfree
Headset
User
Handset
Plain
Codec 1
Plain
Codec 2
Purpose
DSB with
Votronic
handset
Siemens Car
Kit Portable
Siemens
Headset
DSB with
individual
handset
Direct
access to
speech
coder
Direct
access to
speech
coder
Gain setting via AT
command. Defaults:
inBbcGain
outBbcGain
Fix
Adjustable
Adjustable
Adjustable Adjustable Adjustable
4 (24dB)
1 (-6dB)
2 (12dB)
1 (-6dB)
5 (30dB)
2 (-12dB)
4 (24dB)
1 (-6dB)
0 (0dB)
0 (0dB)
0 (0dB)
0 (0dB)
Default audio
interface
2 3)
Power supply
ON (2.65V)
ON (2.65V)
ON (2.65V)
ON (2.65V) OFF (GND) OFF (GND)
Sidetone
ON
---
Adjustable
Adjustable Adjustable Adjustable
Volume control
OFF
Adjustable
Adjustable
Adjustable Adjustable Adjustable
Limiter (receive)
ON
ON
ON
ON
---
---
Compressor
(receive)
---
OFF1)
---
---
---
---
AGC (send)
---
---
ON
---
---
---
Echo control (send)
Suppression Cancellation + --suppression
Suppression
---
---
Noise suppression2)
---
up to 10dB
10dB
---
---
---
MIC input signal for
0dBm0 @ 1024 Hz
(default gain)
23mV
58mV
7.5mV @
23mV
-3dBm0 due
to AGC
315mV
315mV
EP output signal in
mV rms. @ 0dBm0,
1024 Hz, no load
(default gain);
@ 3.14 dBm0
284mV
120mV
default @
max volume
300mV
284mV
default @
default @
max volume max
volume
895mV
895mV
3.7Vpp
3.7Vpp
Sidetone gain at
default settings
22.8dB
-∞ dB
-∞ dB
1)
2)
-∞ dB
Affected by
AGC, 13dB
@ 7.5mV
(MIC)
22.8dB
Adaptive, receive volume increases with higher ambient noise level. The compressor
can be activated by loading an application specific audio parameter set (see [10]).
In audio modes with noise reduction, the microphone input signal for 0dBm shall be
measured with a sine burst signal for a tone duration of 5 seconds and a pause of 2 sec.
The sine signal appears as noise and, after approx. 12 sec, is attenuated by the noise
reduction by up to 10dB.
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3)
Audio mode 5 and 6 are identical. With AT^SAIC, you can easily switch mode 5 to the
second interface. Therefore, audio mode 6 is only kept for compatibility to earlier
Siemens GSM products.
Note: With regard to acoustic shock, the cellular application must be designed to avoid
sending false AT commands that might increase amplification, e.g. for a high
sensitive earpiece. A protection circuit should be implemented in the cellular
application.
6.5.4
Voiceband Receive Path
Test conditions:
• The values specified below were tested to 1kHz and 0dB gain stage, unless otherwise
stated.
• Parameter setup: gs = 0dB means audio mode = 5 for GSM_EPP1 to GSM_EPN1 and 6
for GSM_EPP2 to GSM_EPN2, inBbcGain= 0, inCalibrate = 32767, outBbcGain = 0,
OutCalibrate = 16384, sideTone = 0.
Table 32: Voiceband receive path
Parameter
Min
Typ
Max
Unit
Test condition / remark
Differential output
voltage (peak to peak)
3.33
3.7
4.07
from GSM_EPPx to GSM_EPNx
gs = 0dB @ 3.14 dBm0
no load
Differential output gain
settings (gs) at 6dB
stages (outBbcGain)
-18
dB
Set with AT^SNFO
Fine scaling by DSP
(outCalibrate)
-∞
dB
Set with AT^SNFO
100
mV
gs = 0dB, outBbcGain = 0 and -6dB
Ω
from GSM_EPPx to GSM_EPNx
Output differential
DC offset
Differential output
resistance
Differential load
capacitance
1000
pF
from GSM_EPPx to GSM_EPNx
Absolute gain accuracy
0.8
dB
Variation due to change in
temperature and life time
Attenuation distortion
dB
for 300...3900Hz,
@ GSM_EPPx/ GSM_EPNx
(333Hz) /
@ GSM_EPPx/ GSM_EPNx
(3.66kHz)
Out-of-band
discrimination
60
dB
for f > 4kHz with in-band test
signal@ 1kHz and 1kHz RBW
gs = gain setting
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6.5.5
Voiceband Transmit Path
Test conditions:
• The values specified below were tested to 1kHz and 0dB gain stage, unless otherwise
stated.
• Parameter setup: Audio mode = 5 for GSM_MICP1 to GSM_MICN1 and 6 for
GSM_MICP2 to GSM_MICN2, inBbcGain= 0, inCalibrate = 32767, outBbcGain = 0,
OutCalibrate = 16384, sideTone = 0
Table 33: Voiceband transmit path
Parameter
Min
Typ
Input voltage (peak to peak)
Max
Unit
1.03
Test condition/Remark
GSM_MICP1 to GSM_MICN1,
GSM_MICP2 to GSM_MICN2
Input amplifier gain in 6dB steps
(inBbcGain)
42
dB
Set with AT^SNFI
Fine scaling by DSP (inCalibrate)
-∞
dB
Set with AT^SNFI
Input impedance GSM_MIC1
50
kΩ
Input impedance GSM_MIC2
2.0
kΩ
Microphone supply voltage ON
Ri = 4kΩ (GSM_MIC2 only)
Microphone supply voltage OFF;
Ri = 4kΩ (GSM_MIC2 only)
2.57
2.17
1.77
2.65
2.25
1.85
2.73
2.33
1.93
Microphone supply in POWER
DOWN mode
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@ 100µA
@ 200µA
See Figure 17
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6.6
Air Interface of the XT55/56 GSM Part
Test conditions: All measurements have been performed at Tamb= 25°C, VGSM_BATT+ nom = 4.1V.
The reference points used on XT55/56 are the GSM_BATT+ and GND contacts (test points
are shown in Figure 50).
Table 34: Air Interface
Parameter
Min
Typ
Max
Unit
Frequency range
GSM 850 3)
824
849
MHz
Uplink (MS → BTS)
E-GSM 900 4)
880
915
MHz
GSM 1800
1710
1785
MHz
GSM 1900
1850
1910
MHz
869
894
MHz
3)
Frequency range
GSM 850
Downlink (BTS → MS)
E-GSM 900 4)
925
960
MHz
GSM 1800
1805
1880
MHz
GSM 1900
1930
1990
MHz
RF power @ ARP with 50Ω load
GSM 850
3)
E-GSM 900 4) 1)
GSM 1800
2)
GSM 1900
Number of carriers
GSM 850
Duplex spacing
31
33
35
dBm
31
33
35
dBm
28
30
32
dBm
28
30
32
dBm
3)
124
E-GSM 900 4)
174
GSM 1800
374
GSM 1900
299
GSM 850
3)
45
MHz
E-GSM 900 4)
45
MHz
GSM 1800
95
MHz
GSM 1900
80
MHz
200
kHz
Carrier spacing
Multiplex, Duplex
TDMA / FDMA, FDD
Time slots per TDMA frame
Frame duration
4.615
ms
Time slot duration
577
µs
-102
-107
dBm
Modulation
GMSK
3)
Receiver input sensitivity @ ARP
GSM 850
BER Class II < 2.4%
E-GSM 900 4)
-102
-107
dBm
GSM 1800
-102
-106
dBm
GSM 1900
-102
-105.5
dBm
1)
Power control level PCL 5
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Power control level PCL 0
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4)
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6.7
Electrostatic Discharge
The GSM engine is not protected against Electrostatic Discharge (ESD) in general.
Consequently, it is subject to ESD handling precautions that typically apply to ESD sensitive
components. Proper ESD handling and packaging procedures must be applied throughout
the processing, handling and operation of any application that incorporates a XT55/56
module.
Special ESD protection provided on XT55/56:
Antenna interface: one spark discharge line (spark gap)
SIM interface: clamp diodes for protection against overvoltage.
The remaining ports of XT55/56 are not accessible to the user of the final product (since they
are installed within the device) and therefore, are only protected according to the “Human
Body Model” requirements.
XT55/56 has been tested according to the EN 61000-4-2 standard. The measured values
can be gathered from the following table.
Table 35: Measured electrostatic values
Specification / Requirements
Contact discharge
Air discharge
ESD at SIM port (GSM)
± 4kV
± 8kV
ESD at GSM antenna port
± 4kV
± 8kV
Indirect ESD to GSM part
± 4kV
Indirect ESD to GPS part
± 4kV
ETSI EN 301 489-7
Human Body Model (Test conditions: 1.5 kΩ, 100 pF)
ESD at GPS antenna port
± 1kV
ESD at all other ports
± 1kV
Please note that the values may vary with the individual application design. For example, it matters
whether or not the application platform is grounded over external devices like a computer or other
equipment, such as the Siemens reference application described in Chapter 8.
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6.8
Reliability Characteristics
The test conditions stated below are an extract of the complete test specifications.
Table 36: Summary of reliability test conditions
Type of test
Conditions
Standard
Vibration
Frequency range: 10-20 Hz; acceleration: 3.1mm DIN IEC 68-2-6
amplitude
Frequency range: 20-500 Hz; acceleration: 5g
Duration: 2h per axis = 10 cycles; 3 axes
Shock half-sinus
Acceleration: 500g
DIN IEC 68-2-27
Shock duration: 1msec
1 shock per axis
6 positions (± x, y and z)
Dry heat
Temperature: +70 ±2°C
EN 60068-2-2 Bb
Test duration: 16 h
ETS 300019-2-7
Humidity in the test chamber: < 50%
Temperature
change (shock)
Low temperature: -40°C ±2°C
DIN IEC 68-2-14 Na
High temperature: +85°C ±2°C
Changeover time: < 30s (dual chamber system)
ETS 300019-2-7
Test duration: 1 h
Number of repetitions: 100
Damp heat cyclic
High temperature: +55°C ±2°C
DIN IEC 68-2-30 Db
Low temperature: +25°C ±2°C
Humidity: 93% ±3%
ETS 300019-2-5
Number of repetitions: 6
Test duration: 12h + 12h
Cold (constant
exposure)
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Temperature: -40 ±2°C
DIN IEC 68-2-1
Test duration: 16 h
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Mechanics
The following chapters describe the mechanical dimensions of XT55/56 and give
recommendations for integrating XT55/56 into the host application.
7.1
Mechanical Dimensions of XT55/56
Figure 49 shows the top view of XT55/56. For further details see Figure 51.
Size:
Weight:
35.0 ± 0.15mm x 53.0 ± 0.15mm x 5.1 ± 0.2mm
11g
GPS antenna
connector
GSM antenna
connector
Figure 49: XT55/56 – top view
Figure 50 shows the bottom view of XT55/56 and marks the test points and pads for GSM
antenna connection.
Antenna ground
TP GSM_BATT+
Antenna pad
TP Ground
Figure 50: XT55/56 bottom view
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All dimensions in millimeters
Figure 51: Mechanical dimensions of XT55/56
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7.2
Mounting XT55/56 onto the Application Platform
There are many ways to properly install XT55/56 in the host device. To avoid harming the
module while handling, an efficient approach is to mount the XT55/56 PCB to a frame, plate,
rack or chassis.
When assembling the XT55/56 module plug the B2B connector to the mating header in your
application with applying carefully pressure to that side opposite to the B2B connector
(labeled with “XT_GPS-PBF”).
Fasteners can be M1.6 or M1.8 screws plus suitable washers, circuit board spacers, or
customized screws, clamps, or brackets. Screws must be inserted with the screw head on
the bottom of the XT55/56 PCB. In addition, the board-to-board connection can also be
utilized to achieve better support.
In case you wish to connect the host device using the mounting hole enclosed by the dashed
line (see Figure 52) it is strongly recommended to use a plastic dowel according to Figure 53.
For ordering instructions refer to Table 39.
Figure 52: Mounting holes on XT55/56
For proper grounding it is strongly recommended to use the ground plane on the back side in
addition to the five GND pins of the board-to-board connector. To avoid short circuits ensure
that the remaining sections of the XT55/56 PCB do not come into contact with the host
device since there are a number of test points. Figure 50 shows the positions of all test
points.
To prevent mechanical damage, be careful not to force, bend or twist the module. Be sure it
is positioned flat against the host device.
All the information you need to install an antenna is summarized in Chapter 5. Note that the
antenna pad on the bottom of the XT55/56 PCB must not be influenced by any other PCBs,
components or by the housing of the host device. It needs to be surrounded by a restricted
space as described in Chapter 5.1.2.
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All dimensions in millimeters
Figure 53: Recommended dowel
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7.3
Board-to-Board Connector
This chapter provides specifications for the 80-pin board-to-board connector which serves as
physical interface to the host application. The receptacle assembled on the XT55/56 PCB is
type Hirose DF12C. Mating headers from Hirose are available in different stacking heights.
Table 37: Ordering information DF12 series
Item
Part number
Stacking
height (mm)
HRS number
Receptacle on XT55/56
DF12C(3.0)-80DS-0.5V(81)
3.0
537-0733-9-81
Headers DF12 series
DF12D(3.0)-80DP-0.5V(81)
3.0
537-0803-2-81
DF12E(3.0)-80DP-0.5V(81)
3.0
537-0838-7-81
Notes: The headers listed above are without boss and metal fitting. Please contact Hirose for details
on other types of mating headers. Asterixed HRS numbers denote different types of packaging.
Table 38: Electrical and mechanical characteristics of the Hirose DF12C connector
Parameter
Specification (80 pin board-to-board connector)
Number of contacts
80
Quantity delivered
2000 connectors per tape & reel
Voltage
50V
Rated current
0.3A max per contact
Resistance
0.05 Ohm per contact
Dielectric withstanding voltage
500V RMS min
Operating temperature
-45°C...+125°C
Contact material
phosphor bronze (surface: gold plated)
Insulator material
PA , beige natural
Stacking height
3.0 mm
Insertion force
Withdrawal force 1
21.8N
st
Withdrawal force 50
10N
th
Maximum connection cycles
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50
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Figure 54: Mechanical dimensions of Hirose DF12 connector
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Reference Approval
8.1
Reference Equipment for Type Approval
The Siemens reference setup submitted to type approve XT55/56 consists of the following
components:
• Siemens XT55/56 cellular engine
• Development Support Box (DSB45)
• Flex cable (160 mm) from Hirose DF12C receptacle on XT55/56 to Hirose DF12
connector on DSB45. Please note that this cable is not included in the scope of delivery
of DSB45.
• SIM card reader integrated on DSB45
• Handset type Votronic HH-SI-30.3/V1.1/0
• PC as MMI
Antenna or 50 Ω
cable to system
simulator
Active GPS antenna
Antenna
cable
PC
GSM engine
DSB45
RS-232
Flex cable
160mm
GPS engine
GP
DAI cable for
acoustic measuring
SIM
DAI Box
Power supply
Handset
Acoustic tester
Figure 55: Reference equipment for approval
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8.2
Compliance with FCC Rules and Regulations (XT55 only)
The FCC Equipment Authorization Certification for the XT55 reference application described
in Chapter 8.1 is listed under the
FCC identifier QIPXT55
IC: 267W-XT55
granted to Siemens AG.
The XT55 reference application registered under the above identifier is certified to be in
accordance with the following Rules and Regulations of the Federal Communications
Commission (FCC).
“This device contains GSM 900MHz and GSM 1800MHz functions that are not
operational in U.S. Territories.
This device is to be used only for mobile and fixed applications. The antenna(s) used
for this transmitter must be installed to provide a separation distance of at least 20 cm
from all persons and must not be co-located or operating in conjunction with any other
antenna or transmitter. Users and installers must be provided with antenna installation
instructions and transmitter operating conditions for satisfying RF exposure compliance. Antennas used for this OEM module must not exceed 7dBi gain for mobile and
fixed operating configurations. This device is approved as a module to be installed in
other devices.”
The FCC label of the module must be visible from the outside. If not, the host device is
required to bear a second label stating, “Contains FCC ID QIPXT55”.
Manufacturers of mobile or fixed devices incorporating XT55 modules are advised to include
instructions according to the above mentioned RF exposure statements in end product user
manual.
Please note that changes or modifications not expressly approved by the party responsible
for compliance could void the user’s authority to operate the equipment.
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8.3
Compliance with FCC Rules and Regulations (XT56 only)
The FCC Equipment Authorization Certification for the XT56 reference application described
in Chapter 8.1 is listed under the
FCC identifier QIPXT56
IC: 267W-XT56
granted to Siemens AG.
The XT56 reference application registered under the above identifier is certified to be in
accordance with the following Rules and Regulations of the Federal Communications
Commission (FCC).
“This device contains GSM 1800MHz function that is not operational in U.S. Territories.
This device is to be used only for mobile and fixed applications. The antenna(s) used
for this transmitter must be installed to provide a separation distance of at least 20 cm
from all persons and must not be co-located or operating in conjunction with any other
antenna or transmitter. Users and installers must be provided with antenna installation
instructions and transmitter operating conditions for satisfying RF exposure compliance. Antennas used for this OEM module must not exceed 7dBi gain (GSM 1900)
and 2.2dBi (GSM 850) for mobile and fixed operating configurations. This device is
approved as a module to be installed in other devices.”
The FCC label of the module must be visible from the outside. If not, the host device is
required to bear a second label stating, “Contains FCC ID QIPXT56”.
Manufacturers of mobile or fixed devices incorporating XT56 modules are advised to include
instructions according to the above mentioned RF exposure statements in end product user
manual.
Please note that changes or modifications not expressly approved by the party responsible
for compliance could void the user’s authority to operate the equipment.
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Example Applications
The XT55/56 module offers different options for integrating additional software, such as AVL
and SiRF Demo software. For further details refer to [1] and [4].
Figure 56: Block diagram of XT55/56 for SiRF Demo application
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Figure 57: Block diagram of XT55/56 with AVL application (optional)
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1SS355
GPS antenna (3V)
3V3
470uF
LiIon
battery pack
LDO
ON/OFF
33pF
4 70
GSM antenna
BATT+
33pF
4V3
2.2uF
CRS04
100nF
SI3441DV
LNA
470k
220k
*)
33pF
Charger
3k3
220k
NTC
GPIO4
VCC
RFPC1
GPIO8
XT55
XT56
VCC_RF
*)E S D p ro tectio n
e .g. 1 /5 E S D A 6 V 1 -5 W 6
*)
BATT_TEMP
RFPC0
2x
BLM18
HG 601
10k
BATT+
CHARGE
POWER
BATT+
VANT
LDO
VDD
CCVCC
CCCLK
CCIO
CCRST
CCIN
CCGND
GSM
GPS
ON/OFF
SIM
1nF
47pF
33pF
2.2uF
0R
200nF
V+
6R8
GPO
RESET
6R8
100nF
2x4.7nF
GPI
2x47nF
µC
470k
SDI1
BOOT
SDO1 SEL
SDO2
GND
SDI2
VDD
LP
RXD0
TXD0
TP
TP
TP
TP
TP
TP
LCD
470k
IGT
RING0 RTS0 CTS0
470k
not mounted
EPP2
EPN2
MICP2
MICN2
2.2uF
33pF
3.3k
TXD0
100uF
Keypad
RXD0
CTS0
TP = Test point
RTS0
GPI/INT
TXD1
RXD1
3.3k
BC
847
Oscillator
GND
BATT+
ON/OFF
100k
TP
Figure 58: XT55/56 tracking phone with external µC (example application)
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Figure 58 shows a sample application that incorporates an XT55/56 module and an external
µC which controls the entire application.
This µC must provide two asynchronous serial interfaces for controlling the XT55/56. One
serial interface (TXD0, RXD0, CTS0, RTS0) controls the GSM part. The other serial interface
(TXD1, RXD1) controls the GPS part of the XT55/56 module. It is recommended to use an
interrupt input of the external µC for RING0 detection.
If the application uses IP-based data connections (internet access via GPRS or CSD), the
external µC is responsible for handling the IP protocol.
To update the GSM and GPS software the test points (TP) must be used.
Disclaimer
No warranty, either stated or implied, is provided on the sample schematic diagram shown in
Figure 58 and the information detailed in this section. As functionality and compliance with
national regulations depend to a great amount on the used electronic components and the
individual application layout manufacturers are required to ensure adequate design and
operating safeguards for their products using XT55/56 modules.
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10
List of Parts and Accessories
Table 39: List of parts and accessories
Description
Supplier
Ordering information
Siemens
Siemens ordering number:
XT55
Standard module:
L36880-N8390-A100
Customer IMEI SIM Lock mode: L36880-N8391-A100
XT56
Standard module:
L36880-N8392-A100
Customer IMEI SIM Lock mode: L36880-N8393-A100
Siemens Car Kit Portable
Siemens
Siemens ordering number:
L36880-N3015-A117
DSB45 Support Box
Siemens
Siemens ordering number:
L36880-N8301-A100
BB35 Bootbox
Siemens
Siemens ordering number:
L36880-N8102-A100-1
Votronic Handset
VOTRONIC
Votronic HH-SI-30.3/V1.1/0
VOTRONIC
Entwicklungs- und Produktionsgesellschaft für
elektronische Geräte mbH
Saarbrücker Str. 8
66386 St. Ingbert
Germany
Phone:
Fax:
e-mail:
+49-(0)6 89 4 / 92 55-0
+49-(0)6 89 4 / 92 55-88
contact@votronic.com
Ordering numbers:
91228
91236
SIM card holder incl. push
button ejector and slide-in
tray
Molex
DF12C board-to-board
connector
Hirose
See Chapter 7.3 for details on receptacle on XT55/56 and
mating headers.
Sales contacts are listed in Table 41.
U.FL-R-SMT antenna
connector
Hirose
See Chapter 5.3 for details on U.FL-R-SMT connector,
mating plugs and cables.
Sales contacts are listed in Table 41.
Mounting dowel
Falcom
Ordering number: 511287
GPS antenna
Falcom
Ordering numbers:
FAL-ANT-6
FAL-ANT-7
Sales contacts are listed in Table 40.
Falcom Wireless Communications GmbH
Gewerbering 6
98704 Langewiesen
Germany
Phone: +49-(0)-3677 8042-0
E-Mail: info@falcom.de
Info: http://www.falcom.de
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Table 40: Molex sales contacts (subject to change)
Molex
Molex Deutschland GmbH
American Headquarters
For further information
please click:
Felix-Wankel-Str. 11
4078 Heilbronn-Biberach
Germany
Lisle, Illinois 60532
U.S.A.
http://www.molex.com/
Phone: +49-7066-9555 0
Fax:
+49-7066-9555 29
Email: mxgermany@molex.com
Molex China Distributors
Beijing,
Room 1319, Tower B,
COFCO Plaza
No. 8, Jian Guo Men Nei
Street, 100005
Beijing
P.R. China
Phone: +86-10-6526-9628
Phone: +86-10-6526-9728
Phone: +86-10-6526-9731
Fax:
+86-10-6526-9730
Molex Singapore Pte. Ltd.
Jurong, Singapore
Phone: +65-268-6868
Fax:
+65-265-6044
Phone: +1-800-78MOLEX
Fax:
+1-630-969-1352
Molex Japan Co. Ltd.
Yamato, Kanagawa, Japan
Phone: +81-462-65-2324
Fax:
+81-462-65-2366
Table 41: Hirose sales contacts (subject to change)
Hirose Ltd.
For further information
please click:
http://www.hirose.com
Hirose Electric UK, Ltd
Crownhill Business Centre
22 Vincent Avenue,
Crownhill
Milton Keynes, MK8 OAB
Great Britain
Phone:+44-1908-305400
Fax: +44-1908-305401
XT55/56_hd_v02.96
Hirose Electric (U.S.A.) Inc
2688 Westhills Court
Simi Valley, CA 93065
U.S.A.
Phone: +1-805-522-7958
Fax:
+1-805-522-3217
Hirose Electric GmbH
Zeppelinstrasse 42
73760 Ostfildern
Kemnat 4
Germany
Phone: +49-711-4560-021
Fax
+49-711-4560-729
E-mail info@hirose.de
Hirose Electric Co., Ltd.
5-23, Osaki 5 Chome,
Shinagawa-Ku
Tokyo 141
Japan
Phone: +81-03-3491-9741
Fax:
+81-03-3493-2933
Hirose Electric Co., Ltd.
European Branch
First class Building 4F
Beechavenue 46
1119PV Schiphol-Rijk
Netherlands
Phone: +31-20-6557-460
Fax:
+31-20-6557-469
Page 125 of 125
18.08.2005

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