Quectel Wireless Solutions 201511M85 GSM/GPRS Module User Manual

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Date Submitted	2015-12-14 00:00:00
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Creation Date	2015-12-09 16:17:33
Document Lastmod	2015-12-09 16:17:33
Document Title	User manual
Document Author:	Amy.Feng

M85 Hardware Design
GSM/GPRS Module Series
Rev. M85_Hardware_Design_V3.0
Date: 2015-10-22
www.quectel.com
GSM/GPRS Module Series
M85 Hardware Design
Our aim is to provide customers with timely and comprehensive service. For any
assistance, please contact our company headquarters:
Quectel Wireless Solutions Co., Ltd.
Office 501, Building 13, No.99, Tianzhou Road, Shanghai, China, 200233
Tel: +86 21 5108 6236
Mail: info@quectel.com
Or our local office, for more information, please visit:
http://www.quectel.com/support/salesupport.aspx
For technical support, to report documentation errors, please visit:
http://www.quectel.com/support/techsupport.aspx
Or Email: Support@quectel.com
GENERAL NOTES
QUECTEL OFFERS THIS INFORMATION AS A SERVICE TO ITS CUSTOMERS. THE INFORMATION
PROVIDED IS BASED UPON CUSTOMERS’ REQUIREMENTS. QUECTEL MAKES EVERY EFFORT
TO ENSURE THE QUALITY OF THE INFORMATION IT MAKES AVAILABLE. QUECTEL DOES NOT
MAKE ANY WARRANTY AS TO THE INFORMATION CONTAINED HEREIN, AND DOES NOT ACCEPT
ANY LIABILITY FOR ANY INJURY, LOSS OR DAMAGE OF ANY KIND INCURRED BY USE OF OR
RELIANCE UPON THE INFORMATION. ALL INFORMATION SUPPLIED HEREIN IS SUBJECT TO
CHANGE WITHOUT PRIOR NOTICE.
COPYRIGHT
THIS INFORMATION CONTAINED HERE IS PROPRIETARY TECHNICAL INFORMATION OF
QUECTEL CO., LTD. TRANSMITTABLE, REPRODUCTION, DISSEMINATION AND EDITING OF THIS
DOCUMENT AS WELL AS UTILIZATION OF THIS CONTENTS ARE FORBIDDEN WITHOUT
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RESERVED IN THE EVENT OF A PATENT GRANT OR REGISTRATION OF A UTILITY MODEL OR
DESIGN.
Copyright © Quectel Wireless Solutions Co., Ltd. 2015. All rights reserved.
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About the Document
History
Revision
Date
Author
Description
1.0
2012-07-15
Winter CHEN
Initial
1.1
2013-11-04
Felix YIN
Optimized the parameters of VBAT ripple in Table 33
1.
2.
3.
4.
3.0
2015-03-13
Stone YU/
Hollis WANG
5.
6.
7.
8.
9.
M85_Hardware_Design
Updated module key features in Table 1
Modified pin assignment in Figure 2
Updated DC characteristics of module’s pins in
Table 4
Updated reference circuit for power supply in
Figure 5
Modified over-voltage or under-voltage automatic
shutdown in Section 3.4.2.3
Modified RTC backup in Section 3.6
Modified UART application in Section 3.7.4
Deleted the data call mode in Section 3.13
Added antenna requirement in Section 4.5
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GSM/GPRS Module Series
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Contents
About the Document ................................................................................................................................... 2
Contents ....................................................................................................................................................... 3
Table Index ................................................................................................................................................... 6
Figure Index ................................................................................................................................................. 7
Introduction .......................................................................................................................................... 9
1.1.
Safety Information ................................................................................................................. 10
Product Concept ................................................................................................................................ 11
2.1.
General Description ............................................................................................................... 11
2.2.
Directives and Standards ...................................................................................................... 11
2.2.1. FCC Statement ............................................................................................................... 11
2.2.2. FCC Radiation Exposure Statement .............................................................................. 12
2.3.
Key Features ......................................................................................................................... 12
2.4.
Functional Diagram ............................................................................................................... 14
2.5.
Evaluation Board ................................................................................................................... 15
Application Interface ......................................................................................................................... 16
3.1.
Pin of Module......................................................................................................................... 17
3.1.1. Pin Assignment .............................................................................................................. 17
3.1.2. Pin Description ............................................................................................................... 18
3.2.
Operating Modes ................................................................................................................... 23
3.3.
Power Supply ........................................................................................................................ 24
3.3.1. Power Features of Module ............................................................................................. 24
3.3.2. Decrease Supply Voltage Drop ...................................................................................... 24
3.3.3. Reference Design For Power Supply ............................................................................ 25
3.3.4. Monitor Power Supply .................................................................................................... 26
3.4.
Power On and Down Scenarios ............................................................................................ 26
3.4.1. Power On ....................................................................................................................... 26
3.4.2. Power Down ................................................................................................................... 28
3.4.2.1.
Power Down Module Using the PWRKEY Pin ................................................ 28
3.4.2.2.
Power Down Module Using AT Command ...................................................... 29
3.4.2.3.
Over-voltage or Under-voltage Automatic Shutdown ...................................... 29
3.4.2.4.
Emergency Shutdown Using EMERG_OFF Pin ............................................. 30
3.4.3. Restart ............................................................................................................................ 31
3.5.
Power Saving ........................................................................................................................ 32
3.5.1. Minimum Functionality Mode ......................................................................................... 32
3.5.2. SLEEP Mode .................................................................................................................. 33
3.5.3. Wake up Module from SLEEP Mode ............................................................................. 33
3.5.4. Summary of State Transition .......................................................................................... 33
3.6.
RTC Backup .......................................................................................................................... 34
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3.7.
Serial Interfaces..................................................................................................................... 36
3.7.1. UART Port ...................................................................................................................... 38
3.7.1.1.
The Features of UART Port ............................................................................. 38
3.7.1.2.
The Connection of UART Port ......................................................................... 39
3.7.1.3.
Firmware Upgrade ........................................................................................... 40
3.7.2. Debug Port ..................................................................................................................... 41
3.7.3. Auxiliary UART Port ....................................................................................................... 42
3.7.4. UART Application ........................................................................................................... 42
3.8.
Audio Interfaces..................................................................................................................... 44
3.8.1. Decrease TDD Noise and Other Noise .......................................................................... 45
3.8.2. Microphone Interfaces Design ....................................................................................... 46
3.8.3. Receiver and Speaker Interface Design ........................................................................ 46
3.8.4. Earphone Interface Design ............................................................................................ 48
3.8.5. Loud Speaker Interface Design...................................................................................... 49
3.8.6. Audio Characteristics ..................................................................................................... 49
3.9.
SIM Card Interfaces .............................................................................................................. 50
3.10.
SD Card Interface .................................................................................................................. 53
3.11.
PCM Interface........................................................................................................................ 55
3.11.1. Configuration .................................................................................................................. 56
3.11.2. Timing ............................................................................................................................. 56
3.11.3. Reference Design .......................................................................................................... 58
3.11.4. AT Command ................................................................................................................. 58
3.12.
ADC ....................................................................................................................................... 59
3.13.
Behaviors Of The RI .............................................................................................................. 60
3.14.
Network Status Indication ...................................................................................................... 62
3.15.
Operating Status Indication ................................................................................................... 62
Antenna Interface ............................................................................................................................... 64
4.1.
Reference Design .................................................................................................................. 64
4.2.
RF Output Power ................................................................................................................... 65
4.3.
RF Receiving Sensitivity........................................................................................................ 65
4.4.
Operating Frequencies .......................................................................................................... 66
4.5.
Antenna Requirement ........................................................................................................... 66
4.6.
RF Cable Soldering ............................................................................................................... 67
Electrical, Reliability and Radio Characteristics ............................................................................ 68
5.1.
Absolute Maximum Ratings................................................................................................... 68
5.2.
Operating Temperature ......................................................................................................... 69
5.3.
Power Supply Ratings ........................................................................................................... 69
5.4.
Current Consumption ............................................................................................................ 70
5.5.
Electro-static Discharge ........................................................................................................ 72
Mechanical Dimensions .................................................................................................................... 74
6.1.
Mechanical Dimensions of Module ....................................................................................... 74
6.2.
Recommended Footprint ....................................................................................................... 76
6.3.
Top View of the Module ......................................................................................................... 77
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6.4.
Bottom View of the Module ................................................................................................... 77
Storage and Manufacturing .............................................................................................................. 78
7.1.
Storage .................................................................................................................................. 78
7.2.
Soldering ............................................................................................................................... 79
7.3.
Packaging .............................................................................................................................. 80
Appendix A Reference....................................................................................................................... 82
Appendix B GPRS Coding Scheme ................................................................................................. 87
10 Appendix C GPRS Multi-slot Class .................................................................................................. 89
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Table Index
TABLE 1: MODULE KEY FEATURES ............................................................................................................... 12
TABLE 2: CODING SCHEMES AND MAXIMUM NET DATA RATES OVER AIR INTERFACE ........................ 14
TABLE 3: PIN DESCRIPTION ........................................................................................................................... 18
TABLE 4: OVERVIEW OF OPERATING MODES ............................................................................................. 23
TABLE 5: SUMMARY OF STATE TRANSITION ............................................................................................... 33
TABLE 6: LOGIC LEVELS OF THE UART INTERFACE .................................................................................. 37
TABLE 7: PIN DEFINITION OF THE UART INTERFACES .............................................................................. 37
TABLE 8: PIN DEFINITION OF AUDIO INTERFACE ....................................................................................... 44
TABLE 9: AOUT3 OUTPUT CHARACTERISTICS ............................................................................................ 45
TABLE 10: TYPICAL ELECTRET MICROPHONE CHARACTERISTICS ......................................................... 49
TABLE 11: TYPICAL SPEAKER CHARACTERISTICS ..................................................................................... 49
TABLE 12: PIN DEFINITION OF THE SIM INTERFACE .................................................................................. 50
TABLE 13: PIN DEFINITION OF THE SD CARD INTERFACE ........................................................................ 54
TABLE 14: PIN DEFINITION OF THE SD CARD INTERFACE ........................................................................ 54
TABLE 15: PIN DEFINITION OF PCM INTERFACE ......................................................................................... 55
TABLE 16: CONFIGURATION........................................................................................................................... 56
TABLE 17: QPCMON COMMAND DESCRIPTION .......................................................................................... 59
TABLE 18: QPCMVOL COMMAND DESCRIPTION ......................................................................................... 59
TABLE 19: PIN DEFINITION OF THE ADC ...................................................................................................... 60
TABLE 20: CHARACTERISTICS OF THE ADC ................................................................................................ 60
TABLE 21: BEHAVIORS OF THE RI ................................................................................................................. 60
TABLE 22: WORKING STATE OF THE NETLIGHT .......................................................................................... 62
TABLE 23: PIN DEFINITION OF THE STATUS ................................................................................................ 63
TABLE 24: PIN DEFINITION OF THE RF_ANT ................................................................................................ 64
TABLE 25: THE MODULE CONDUCTED RF OUTPUT POWER .................................................................... 65
TABLE 26: THE MODULE CONDUCTED RF RECEIVING SENSITIVITY ....................................................... 65
TABLE 27: THE MODULE OPERATING FREQUENCIES ................................................................................ 66
TABLE 28: ANTENNA CABLE REQUIREMENTS ............................................................................................. 66
TABLE 29: ANTENNA REQUIREMENTS.......................................................................................................... 66
TABLE 30: ABSOLUTE MAXIMUM RATINGS .................................................................................................. 68
TABLE 31: OPERATING TEMPERATURE........................................................................................................ 69
TABLE 32: THE MODULE POWER SUPPLY RATINGS .................................................................................. 69
TABLE 33: THE MODULE CURRENT CONSUMPTION .................................................................................. 70
TABLE 34: THE ESD ENDURANCE (TEMPERATURE: 25ºC, HUMIDITY: 45%) ............................................ 73
TABLE 35: REEL PACKING .............................................................................................................................. 81
TABLE 36: RELATED DOCUMENTS ................................................................................................................ 82
TABLE 37: TERMS AND ABBREVIATIONS ...................................................................................................... 83
TABLE 38: DESCRIPTION OF DIFFERENT CODING SCHEMES .................................................................. 87
TABLE 39: GPRS MULTI-SLOT CLASSES ...................................................................................................... 89
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Figure Index
FIGURE 1: MODULE FUNCTIONAL DIAGRAM ............................................................................................... 15
FIGURE 2: PIN ASSIGNMENT ......................................................................................................................... 17
FIGURE 3: VOLTAGE RIPPLE DURING TRANSMITTING .............................................................................. 24
FIGURE 4: REFERENCE CIRCUIT FOR THE VBAT INPUT ........................................................................... 25
FIGURE 5: REFERENCE CIRCUIT FOR POWER SUPPLY ............................................................................ 25
FIGURE 6: TURN ON THE MODULE WITH AN OPEN-COLLECTOR DRIVER .............................................. 26
FIGURE 7: TURN ON THE MODULE WITH A BUTTON .................................................................................. 27
FIGURE 8: TURN-ON TIMING .......................................................................................................................... 27
FIGURE 9: TURN-OFF TIMING ........................................................................................................................ 28
FIGURE 10: AN OPEN-COLLECTOR DRIVER FOR EMERG_OFF ................................................................ 30
FIGURE 11: REFERENCE CIRCUIT FOR EMERG_OFF BY USING BUTTON .............................................. 31
FIGURE 12: TIMING OF RESTARTING SYSTEM ............................................................................................ 31
FIGURE 13: TIMING OF RESTARTING SYSTEM AFTER EMERGENCY SHUTDOWN ................................ 32
FIGURE 14: VRTC IS SUPPLIED BY A NON-CHARGEABLE BATTERY ........................................................ 35
FIGURE 15: VRTC IS SUPPLIED BY A RECHARGEABLE BATTERY ............................................................ 35
FIGURE 16: VRTC IS SUPPLIED BY A CAPACITOR ...................................................................................... 36
FIGURE 17: REFERENCE DESIGN FOR FULL-FUNCTION UART ................................................................ 39
FIGURE 18: REFERENCE DESIGN FOR UART PORT ................................................................................... 40
FIGURE 19: REFERENCE DESIGN FOR UART PORT WITH HARDWARE FLOW CONTROL .................... 40
FIGURE 20: REFERENCE DESIGN FOR FIRMWARE UPGRADE ................................................................. 41
FIGURE 21: REFERENCE DESIGN FOR DEBUG PORT ............................................................................... 41
FIGURE 22: REFERENCE DESIGN FOR AUXILIARY UART PORT ............................................................... 42
FIGURE 23: LEVEL MATCH DESIGN FOR 3.3V SYSTEM.............................................................................. 42
FIGURE 24: SKETCH MAP FOR RS-232 INTERFACE MATCH ...................................................................... 43
FIGURE 25: REFERENCE DESIGN FOR AIN1&AIN2 ..................................................................................... 46
FIGURE 26: HANDSET INTERFACE DESIGN FOR AOUT1 ........................................................................... 46
FIGURE 27: SPEAKER INTERFACE DESIGN WITH AN AMPLIFIER FOR AOUT1 ....................................... 47
FIGURE 28: HANDSET INTERFACE DESIGN FOR AOUT2 ........................................................................... 47
FIGURE 29: SPEAKER INTERFACE DESIGN WITH AN AMPLIFIER FOR AOUT2 ....................................... 48
FIGURE 30: EARPHONE INTERFACE DESIGN .............................................................................................. 48
FIGURE 31: LOUD SPEAKER INTERFACE DESIGN ...................................................................................... 49
FIGURE 32: REFERENCE CIRCUIT FOR SIM1 INTERFACE WITH 8-PIN SIM CARD HOLDER ................. 51
FIGURE 33: REFERENCE CIRCUIT FOR SIM1 INTERFACE WITH THE 6-PIN SIM CARD HOLDER ......... 52
FIGURE 34: REFERENCE CIRCUIT FOR SIM2 INTERFACE WITH THE 6-PIN SIM CARD HOLDER ......... 52
FIGURE 35: REFERENCE CIRCUIT FOR SD CARD ...................................................................................... 54
FIGURE 36: LONG SYNCHRONIZATION & SIGN EXTENSION DIAGRAM ................................................... 57
FIGURE 37: LONG SYNCHRONIZATION & ZERO PADDING DIAGRAM....................................................... 57
FIGURE 38: SHORT SYNCHRONIZATION & SIGN EXTENSION DIAGRAM ................................................. 57
FIGURE 39: SHORT SYNCHRONIZATION & ZERO PADDING DIAGRAM .................................................... 58
FIGURE 40: REFERENCE DESIGN FOR PCM ............................................................................................... 58
FIGURE 41: RI BEHAVIOR OF VOICE CALLING AS A RECEIVER ................................................................ 61
FIGURE 42: RI BEHAVIOR AS A CALLER ....................................................................................................... 61
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FIGURE 43: RI BEHAVIOR OF URC OR SMS RECEIVED ............................................................................. 61
FIGURE 44: REFERENCE DESIGN FOR NETLIGHT ..................................................................................... 62
FIGURE 45: REFERENCE DESIGN FOR STATUS.......................................................................................... 63
FIGURE 46: REFERENCE DESIGN FOR RF .................................................................................................. 64
FIGURE 47: RF SOLDERING SAMPLE ........................................................................................................... 67
FIGURE 48: M85 MODULE TOP AND SIDE DIMENSIONS (UNIT: MM) ......................................................... 74
FIGURE 49: M85 MODULE BOTTOM DIMENSIONS (UNIT: MM) ................................................................... 75
FIGURE 50: THE PAD DIMENSIONS (UNIT: MM) ........................................................................................... 75
FIGURE 51: RECOMMENDED FOOTPRINT (UNIT: MM) ................................................................................ 76
FIGURE 52: TOP VIEW OF THE MODULE ...................................................................................................... 77
FIGURE 53: BOTTOM VIEW OF THE MODULE .............................................................................................. 77
FIGURE 54: RAMP-SOAK-SPIKE REFLOW PROFILE.................................................................................... 79
FIGURE 55: TAPE AND REEL INFORMATION ................................................................................................ 81
FIGURE 56: RADIO BLOCK STRUCTURE OF CS-1, CS-2 AND CS-3 ........................................................... 87
FIGURE 57: RADIO BLOCK STRUCTURE OF CS-4 ....................................................................................... 88
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GSM/GPRS Module Series
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Introduction
This document defines the M85 module and describes its hardware interface which are connected with
the customer application and the air interface.
This document can help you quickly understand module interface specifications, electrical and
mechanical details. Associated with application notes and user guide, you can use M85 module to design
and set up mobile applications easily.
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1.1. Safety Information
The following safety precautions must be observed during all phases of the operation, such as usage,
service or repair of any cellular terminal or mobile incorporating M85 module. Manufacturers of the
cellular terminal should send the following safety information to users and operating personnel and to
incorporate these guidelines into all manuals supplied with the product. If not so, Quectel does not take on
any liability for customer failure to comply with these precautions.
Full attention must be given to driving at all times in order to reduce the risk of an
accident. Using a mobie while driving (even with a handsfree kit) cause distraction
and can lead to an accident. You must comply with laws and regulations restrcting
the use of wireless devices while driving.
Switch off the cellular terminal or mobile before boarding an aircraft. Make sure it
switched off. The operation of wireless appliances in an aircraft is forbidden to
prevent interference with communication systems. Consult the airline staff about
the use of wireless devices on boarding the aircraft. If your device offers a Flight
Mode which must be enabled prior to boarding an aircraft.
Switch off your wireless device when in hospitals or clinics or other health care
facilities. These requests are desinged to prevent possible interference with
sentitive medical equipment.
Cellular terminals or mobiles operate over radio frequency signal and cellular
network and cannot be guaranteed to connect in all conditions, for example no
mobile fee or an invalid SIM card. While you are in this condition and need
emergent help, please remember using emergency call. In order to make or
receive call, the cellular terminal or mobile must be switched on and in a service
area with adequate cellular signal strength.
Your cellular terminal or mobile contains a transmitter and receiver. When it is ON ,
it receives and transmits radio frequency energy. RF interference can occur if it is
used close to TV set, radio, computer or other electric equipment.
In locations with potencially explosive atmospheres, obey all posted signs to turn
off wireless devices such as your phone or other cellular terminals. Areas with
potencially exposive atmospheres including fuelling areas, below decks on boats,
fuel or chemical transfer or storage facilities, areas where the air contains
chemicals or particles such as grain, dust or metal powders.
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GSM/GPRS Module Series
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Product Concept
2.1. General Description
M85 is a Quad-band GSM/GPRS engine that works at frequencies of GSM850MHz, EGSM900MHz,
DCS1800MHz and PCS1900MHz. The M85 features GPRS multi-slot class 12 and supports the GPRS
coding schemes CS-1, CS-2, CS-3 and CS-4. For more details about GPRS multi-slot classes and coding
schemes, please refer to the Appendix B & C.
With a tiny profile of 24.5mm × 25.3mm × 2.6mm, the module can meet almost all the requirements for
M2M applications, including Vehicles and Personal Tracking, Security System, Wireless POS, Industrial
PDA, Smart Metering, and Remote Maintenance & Control, etc.
M85 is an SMD type module with LCC package, which can be easily embedded into applications. It
provides abundant hardware interfaces like PCM and SD Card Interface.
Designed with power saving technique, the current consumption of M85 is as low as 1.3 mA in SLEEP
mode when DRX is 5.
M85 is integrated with Internet service protocols, such as TCP/UDP, FTP and PPP. Extended AT
commands have been developed for you to use these Internet service protocols easily.
The module fully complies with the RoHS directive of the European Union.
2.2. Directives and Standards
The M85 module is designed to comply with the FCC statements. FCC ID: XMR201511M85
The Host system using M85 should have label ―contains FCC ID: XMR201511M85‖.
2.2.1. FCC Statement
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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2.2.2. FCC Radiation Exposure Statement
This equipment complies with FCC radiation exposure limits set forth for an uncontrolled environment.
This equipment should be installed and operated with minimum distance 20cm between the radiator and
your body as well as kept minimum 20cm from radio antenna depending on the Mobile status of this
module usage. This module should NOT be installed and operating simultaneously with other radio. The
manual of the host system, which uses M85, must include RF exposure warning statement to advice user
should keep minimum 20cm from the radio antenna of M85 module depending on the Mobile status. Note:
If a portable device (such as PDA) uses M85 module, the device needs to do permissive change and SAR
testing.
The following list indicates the performance of antenna gain in certificate testing.
Part
Number
Frequency Range (MHz)
Peak Gain
(XZ-V)
Average
Gain(XZ-V)
VS
WR
3R007
GSM850:824～894MHz
EGSM900:880～960MHz
DCS1800:1710～1880MHz
PCS1900: 1850～1990MHz
1 dBi typ.
1 dBi typ.
2 max
Impedanc
50Ω
2.3. Key Features
The following table describes the detailed features of M85 module.
Table 1: Module Key Features
Feature
Implementation
Power Supply
Single supply voltage: 3.3V~4.6V
Typical supply voltage: 4.0V
Power Saving
Typical power consumption in SLEEP mode: 1.3 mA@ DRX=5
1.2 mA@ DRX=9
Frequency Bands




GSM Class
Small MS
Transmitting Power


M85_Hardware_Design
Quad-band: GSM850, EGSM900, DCS1800, PCS1900
The module can search these frequency bands automatically
The frequency bands can be set by AT command
Compliant to GSM Phase 2/2+
Class 4 (2W) at GSM850 and EGSM900
Class 1 (1W) at DCS1800 and PCS1900
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


GPRS multi-slot class 12 (default)
GPRS multi-slot class 1~12 (configurable)
GPRS mobile station class B






GPRS data downlink transfer: max. 85.6kbps
GPRS data uplink transfer: max. 85.6kbps
Coding scheme: CS-1, CS-2, CS-3 and CS-4
Support the protocols PAP (Password Authentication Protocol)
usually used for PPP connections
Internet service protocols:
TCP/UDP/FTP/PPP/HTTP/NTP/MMS/SMTP/PING
Support Packet Broadcast Control Channel (PBCCH)
Support Unstructured Supplementary Service Data (USSD)
Temperature Range



Normal operation: -35°C ~ +80°C
Restricted operation: -40°C ~ -35°C and +80°C ~ +85°C 1)
Storage temperature: -45°C ~ +90°C
SMS


Text and PDU mode
SMS storage: SIM card
SIM Interfaces
Support SIM card: 1.8V, 3V
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)
 Echo Suppression
 Noise Reduction
 Embedded one amplifier of class AB with maximum driving power up
to 870mW
UART Interfaces
UART Port:
 Seven lines on UART port interface
 Used for AT command, GPRS data
 Multiplexing function
 Support autobauding from 4800bps to 115200bps
Debug Port:
 Two lines on debug port interface DBG_TXD and DBG_RXD
 Use for software debugging and log output
Auxiliary Port:
 Used for AT command
Phonebook Management
Support phonebook types: SM, ME, ON, MC, RC, DC, LD, LA
SIM Application Toolkit
Support SAT class 3, GSM 11.14 Release 99
Real Time Clock
Supported
GPRS Connectivity
DATA GPRS

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Physical Characteristics
Size: 25.3±0.15 × 24.5±0.15 × 2.6±0.2mm
Weight: Approx. 3.3g
Firmware Upgrade
Firmware upgrade via UART Port
Antenna Interface
Connected to antenna pad with 50 Ohm impedance control
NOTE
1)
When the module works within this temperature range, the deviations from the GSM specification may
occur. For example, the frequency error or the phase error will be increased.
Table 2: Coding Schemes and Maximum Net Data Rates over Air Interface
Coding scheme
1 Timeslot
2 Timeslot
4 Timeslot
CS-1
9.05kbps
18.1kbps
36.2kbps
CS-2
13.4kbps
26.8kbps
53.6kbps
CS-3
15.6kbps
31.2kbps
62.4kbps
CS-4
21.4kbps
42.8kbps
85.6kbps
2.4. Functional Diagram
The following figure shows a block diagram of M85 and illustrates the major functional parts.




Radio frequency part
Serial Flash
Power management
The Peripheral interface
—Power supply
—Turn-on/off interface
—UART interfaces
—Audio interfaces
—SIM interfaces
—SD interface
—PCM interface
—ADC interface
—RTC interface
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—RF interface
RF_ANT
ESD
RF PAM
VBAT
PWRKEY
PMU
EMERG_OFF
Reset
VRTC
RTC
SIM Interfaces
GPIO&
Status&
Netlight
UART
RF Transceiver
BB&RF
SIM
Interface
GPIO&PWM
Serial Interface
MEMORY
26MHz
ADC
ADC
PCM
Interface
PCM
SD
Interface
SD
Audio
Audio
Serial Flash
Figure 1: Module Functional Diagram
2.5. Evaluation Board
In order to help customer to develop applications with M85, Quectel supplies an evaluation board (EVB),
RS-232 to USB cable, power adapter, earphone, antenna and other peripherals to control or test the
module. For details, please refer to the document [12].
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GSM/GPRS Module Series
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Application Interface
The module adopts LCC package and has 83 pins. The following chapters provide detailed descriptions
about these pins below.













Power supply
Power on/down
Power saving
RTC
Serial interfaces
Audio interfaces
SIM interfaces
SD interface
PCM interface
ADC
RI
NETLIGHT
Status
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3.1. Pin of Module
SIM1_PRESENCE
VRTC
RESERVED
VDD_EXT
GND
RF_ANT
GND
GND
GND
VBAT
GND
VBAT
VBAT
VBAT
SIM2_CLK
SIM2_VDD
SIM2_DATA
SIM2_RST
3.1.1. Pin Assignment
74 73 72 71 70 69 68 67 66 65 64 63 62 61 60 59 58 57
RESERVED
56 SIM1_VDD
ADC0
55 SIM1_CLK
RESERVED
NETLIGHT
SPK2P
AGND
GND
51 RTS
MIC2P
RESERVED
50 RXD
MIC2N
Top view
54 SIM1_DATA
53 SIM1_RST
52 SIM_GND
82
MIC1P 9
48 CTS
80 GND
83
RESERVED 76
MIC1N 10
49 TXD
81 GND
RESERVED 75
47 DTR
SPK1N
11
SPK1P
12
LOUDSPKN
13
LOUDSPKP
14
43 DBG_RXD
PWRKEY 15
42 DBG_TXD
RESERVED 77
79
GND
46 RI
78
45 DCD
RESERVED
44 RESERVED
STATUS
16
41 RXD_AUX
EMERG_OFF
17
40 TXD_AUX
PCM_IN
18
39 RESERVED
PCM_CLK
19
38 RESERVED
VBAT
SIM2
GND
Power
SIM1
RESERVED
RF
SD
UART
Audio
Other
PCM
GND
SD_DATA0
SD_CLK
SD_CMD
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
RESERVED
PCM_SYNC
PCM_OUT
20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37
ADC
Figure 2: Pin Assignment
NOTE
Keep all reserved pins open.
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3.1.2. Pin Description
Table 3: Pin Description
Power Supply
PIN NAME
VBAT
VRTC
PIN NO.
I/O
67, 68, 69,
70
59
VDD_EXT
60
GND
37, 61, 62,
64~66,
79~82,
I/O
DC
CHARACTERISTICS
COMMENT
Main power supply of
module:
VBAT=3.3V~4.6V
Vmax=4.6V
Vmin=3.3V
Vnorm=4.0V
Make sure that
supply sufficient
current in a
transmitting burst
typically rises to
1.6A.
Power supply for RTC.
Charging for backup
battery or golden
capacitor when the
VBAT is applied.
VImax=3.3V
VImin=1.5V
VInorm=2.8V
VOmax=3V
VOmin=2V
VOnorm=2.8V
Iout(max)=2mA
Iin≈10uA
If unused, keep
this pin open.
Vmax=2.9V
Vmin=2.7V
Vnorm=2.8V
Imax=20mA
1. If unused, keep
this pin open.
2. Recommend to
add a 2.2~4.7uF
bypass capacitor,
when using this
pin for power
supply.
COMMENT
DESCRIPTION
Supply 2.8V voltage for
external circuit.
Ground
Turn on/off
PIN NAME
PWRKEY
PIN NO.
15
I/O
DESCRIPTION
DC
CHARACTERISTICS
Power on/off key.
PWRKEY should be pulled
down for a moment to turn
on or turn off the system.
VILmax=
0.1×VBAT
VIHmin=
0.6×VBAT
VIHmax=3.1V
Emergency Shutdown
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PIN NAME
EMERG_
OFF
PIN NO.
17
DC
CHARACTERISTICS
I/O
DESCRIPTION
COMMENT
Emergency off. Pulled
down for at least 40ms,
which will turn off the
module in case of
emergency. Use it only
when shutdown via
PWRKEY or AT command
cannot be achieved.
VILmax=0.45V
VIHmin=1.35V
Vopenmax=1.8V
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
Indicate module’s
operating status. Output
high level when module
turns on, while output low
level when module turns
off.
VOHmin=
0.85×VDD_EXT
VOLmax=
0.15×VDD_EXT
If unused, keep
this pin open.
DC
CHARACTERISTICS
COMMENT
Open
drain/collector
driver required in
cellular device
application.
If unused, keep
this pin open.
Module Indicator
PIN NAME
STATUS
PIN NO.
16
Audio Interface
PIN NAME
PIN NO.
I/O
DESCRIPTION
MIC1P
MIC1N
9, 10
Channel 1 positive and
negative voice input
MIC2P
MIC2N
7, 8
Channel 2 positive and
negative voice input
SPK1P
SPK1N
12, 11
Channel 1 positive and
negative voice output
SPK2P
Channel 2 voice output
AGND
LOUDSPKN
LOUDSPKP
13, 14
M85_Hardware_Design
Analog ground. Separate
ground connection for
external audio circuits.
If unused, keep
these pins open.
1. If unused, keep
these pins open.
2. Support both
voice and
ringtone output.
Refer to Section 3.8
Channel 3 positive and
negative voice output
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If unused, keep
this pin open.
1. If unused, keep
these pins open.
2. Integrate a
Class- AB
amplifier
internally.
3. Support both
voice and
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ringtone output.
Network Status Indicator
PIN NAME
PIN NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
If unused, keep
this pin open.
Network status
indication
VOHmin=
0.85×VDD_EXT
VOLmax=
0.15×VDD_EXT
PIN NAME
PIN NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
DTR
47
Data terminal ready
RXD
50
Receive data
TXD
49
Transmit data
RTS
51
Request to send
CTS
48
Clear to send
RI
46
Ring indication
If only use TXD,
RXD and GND to
communicate,
recommended
connecting RTS
to GND via 0R
resistor and
keeping other
pins open.
DCD
45
Data carrier detection
VILmin=0V
VILmax=
0.25×VDD_EXT
VIHmin=
0.75×VDD_EXT
VIHmax=
VDD_EXT+0.2
VOHmin=
0.85×VDD_EXT
VOLmax=
0.15×VDD_EXT
PIN NAME
PIN NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
DBG_TXD
42
Transmit data
Same as above
If unused, keep
these pins open.
NETLIGHT
UART Port
Debug Port
DBG_RXD
43
Receive data
PIN NAME
PIN NO.
I/O
DESCRIPTION
TXD_AUX
40
Transmit data
Auxiliary Port
RXD_AUX
41
Receive data
PIN NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
Same as above
If unused, keep
these pins open.
DC
CHARACTERISTICS
COMMENT
SIM Interface
PIN NAME
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SIM1_VDD
56
SIM2_VDD
71
SIM1_CLK
55
SIM2_CLK
SIM1_ DATA
Power supply for SIM
card
The voltage can be
selected by software
automatically. Either
1.8V or 3V.
SIM clock
VOLmax=
0.15×SIM_VDD
VOHmin=
0.85×SIM_VDD
SIM data
VILmax=
0.25×SIM_VDD
VIHmin=
0.75×SIM_VDD
VOLmax=
0.15×SIM_VDD
VOHmin=
0.85×SIM_VDD
SIM reset
VOLmax=
0.15×SIM_VDD
VOHmin=
0.85×SIM_VDD
SIM card detection
VILmin=0V
VILmax=
0.25×VDD_EXT
VIHmin=
0.75×VDD_EXT
VIHmax=
VDD_EXT+0.2
72
54
I/O
SIM2_DATA
73
SIM1_RST
53
SIM2_RST
74
SIM1_
PRESENCE
57
SIM_GND
52
All signals of SIM
interface should be
protected against
ESD with a TVS
diode array.
Maximum trace
length is 200mm
from the module
pad to SIM card
holder.
If unused, keep
these pins open.
SIM ground
ADC
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
General purpose
analog to digital
converter.
Voltage range:
0V to 2.8V
If unused, keep
this pin open.
PIN NAME
PIN NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
PCM_CLK
19
PCM clock
PIN NAME
ADC0
PIN NO.
PCM
PCM_IN
18
M85_Hardware_Design
PCM data input
VILmin= 0V
VILmax=
0.25×VDD_EXT
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COMMENT
If unused, keep
these pins open.
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PCM_OUT
PCM_SYNC
20
PCM data output
21
PCM frame
synchronization
PIN NO.
I/O
DESCRIPTION
VIHmin=
0.75×VDD_EXT
VIHmax=
VDD_EXT+0.2
VOHmin=
0.85×VDD_EXT
VOLmax=
0.15×VDD_EXT
If unused, keep
these pins open.
DC
CHARACTERISTICS
COMMENT
VILmin=0V
VILmax=
0.25×VDD_EXT
VIHmin=
0.75×VDD_EXT
VIHmax=
VDD_EXT+0.2
VOHmin=
0.85×VDD_EXT
VOLmax=
0.15×VDD_EXT
If unused, keep
these pins open.
COMMENT
SD Card
PIN NAME
SD_CMD
34
SD command
SD_CLK
35
SD clock
SD_DATA0
36
I/O
SD data
Antenna Interface
PIN NAME
PIN NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
RF_ANT
63
I/O
RF antenna pad
Impedance of 50Ω
I/O
DESCRIPTION
DC
CHARACTERISTICS
Other Interface
PIN NAME
PIN NO.
RESERVD
1, 3,
22~33,
38, 39,
44, 58,
75~78,
83
M85_Hardware_Design
COMMENT
Keep these pins
open.
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3.2. Operating Modes
The table below briefly summarizes the various operating modes in the following chapters.
Table 4: Overview of Operating Modes
Mode
Normal
Operation
Function
GSM/GPRS
Sleep
After enabling sleep mode by AT+QSCLK=1, the module will
automatically go into Sleep Mode if DTR is set to high level and
there is no interrupt (such as GPIO interrupt or data on UART
port). In this case, the current consumption of module will reduce
to the minimal level. During Sleep Mode, the module can still
receive paging message and SMS from the system normally.
GSM IDLE
Software is active. The module has registered to the GSM
network, and the module is ready to send and receive GSM data.
GSM TALK
GSM connection is ongoing. In this mode, the power
consumption is decided by the configuration of Power Control
Level (PCL), dynamic DTX control and the working RF band.
GPRS IDLE
The module is not registered to GPRS network. The module is
not reachable through GPRS channel.
GPRS
STANDBY
The module is registered to GPRS network, but no GPRS PDP
context is active. The SGSN knows the Routing Area where the
module is located at.
GPRS READY
The PDP context is active, but no data transfer is ongoing. The
module is ready to receive or send GPRS data. The SGSN
knows the cell where the module is located at.
GPRS DATA
There is GPRS data in transfer. In this mode, power consumption
is decided by the PCL, working RF band and GPRS multi-slot
configuration.
POWER DOWN
Normal shutdown by sending the AT+QPOWD=1 command or using the PWRKEY
or the EMERG_OFF1) pin. The power management ASIC disconnects the power
supply from the base band part of the module, and only the power supply for the
RTC is remained. Software is not active. The UART interfaces are not accessible.
Operating voltage (connected to VBAT) remains applied.
Minimum
Functionality
Mode (without
removing power
supply)
AT+CFUN command can set the module to a minimum functionality mode without
removing the power supply. In this case, the RF part of the module will not work or
the SIM card will not be accessible, or both RF part and SIM card will be disabled,
but the UART port is still accessible. The power consumption in this case is very
low.
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NOTE
Use the EMERG_OFF pin only when failing to turn off the module by the command AT+QPOWD=1 and
the PWRKEY pin. For more details, please refer to the Section 3.4.2.4.
3.3. Power Supply
3.3.1. Power Features of Module
The power supply is one of the key issues in designing GSM terminals. Because of the 577us radio burst
in GSM every 4.615ms, power supply must be able to deliver high current peaks in a burst period. During
these peaks, drops on the supply voltage must not exceed minimum working voltage of module.
For the M85 module, the max current consumption could reach to 1.6A during a transmit burst. It will
cause a large voltage drop on the VBAT. In order to ensure stable operation of the module, it is
recommended that the max voltage drop during the transmit burst does not exceed 400mV.
4.615ms
577us
Burst:1.6A
IBAT
VBAT
Vdrop
Figure 3: Voltage Ripple during Transmitting
3.3.2. Decrease Supply Voltage Drop
The power supply range of the module is 3.3V to 4.6V. Make sure that the input voltage will never drop
below 3.3V even in a transmitting burst. If the power voltage drops below 3.3V, the module could turn off
automatically. For better power performance, it is recommended to place a 100uF tantalum capacitor with
low ESR (ESR=0.7Ω) and ceramic capacitor 100nF, 33pF and 10pF near the VBAT pin. The reference
circuit is illustrated in Figure 4.
The VBAT route should be wide enough to ensure that there is not too much voltage drop during transmit
burst. The width of trace should be no less than 2mm and the principle of the VBAT route is the longer
route, the wider trace.
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VBAT
C1
100uF
C2
100nF
C3
C4
10pF
33pF
0603
0603
GND
Figure 4: Reference Circuit for the VBAT Input
3.3.3. Reference Design For Power Supply
The power design for the module is very important, since the performance of power supply for the module
largely depends on the power source. The power supply is capable of providing the sufficient current up to
2A at least. If the voltage drop between the input and output is not too high, it is suggested to use a LDO
as module’s power supply. If there is a big voltage difference between the input source and the desired
output (VBAT), a switcher power converter is recommended to use as a power supply.
Figure 5 shows a reference design for +5V input power source. The designed output for the power supply
is 4.0V and the maximum load current is 3A. In addition, in order to get a stable output voltage, a zener
diode is placed close to the pins of VBAT. As to the zener diode, it is suggested to use a zener diode
whose reverse zener voltage is 5.1V and dissipation power is more than 1 Watt.
MIC29302WU
U1
DC_IN
VBAT
470uF
ADJ
R1
51K
GND
C2
OUT 4
EN
C1
2 IN
R2
124K
R4
R3
56K
100nF
470R
C3
470uF
C4
D1
100nF
5.1V
R5
4.7K
MCU_POWER_ON/OFF
R6
47K
Figure 5: Reference Circuit for Power Supply
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NOTE
It is suggested to control the module’s main power supply (VBAT) via LDO enable pin to restart the
module when the module has become abnormal. Power switch circuit like P-channel MOSFET switch
circuit can also be used to control VBAT.
3.3.4. Monitor Power Supply
The command AT+CBC can be used to monitor the supply voltage of the module. The unit of the
displayed voltage is mV.
For details, please refer to the document [1].
3.4. Power On and Down Scenarios
3.4.1. Power On
The module can be turned on by driving the pin PWRKEY to a low level voltage. An open collector driver
circuit is suggested to control the PWRKEY. A simple reference circuit is illustrated as below.
PWRKEY
4.7K
Turn on pulse
47K
Figure 6: Turn on the Module with an Open-collector Driver
NOTES
1.
M85 module is set to autobauding mode (AT+IPR=0) by default. In the autobauding mode, URC
―RDY‖ is not reported to the host controller after module is powered on. When the module is powered
on after a delay of 4 or 5 seconds, it can receive AT command. Host controller should first send an AT
string in order that the module can detect baud rate of host controller, and it should continue to send
the next AT string until receiving OK string from the module. Then enter AT+IPR=x;&W to set a fixed
baud rate for the module and save the configuration to flash memory of the module. After these
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2.
configurations, the URC RDY would be received from the UART Port of the module every time when
the module is powered on. For more details, refer to the section AT+IPR in document [1].
AT command response indicates module is turned on successfully, or else the module fails to be
turned on.
The other way to control the PWRKEY is through a button directly. A TVS component is indispensable to
be placed nearby the button for ESD protection. For the best performance, the TVS component must be
placed nearby the button. When pressing the key, electrostatic strike may generate from finger. A
reference circuit is shown in the following figure.
K1
PWRKEY
TVS
Close to K1
Figure 7: Turn on the Module with a Button
The turn-on timing is illustrated as the following figure.
T1
54ms
VBAT
EMERG_OFF
(INPUT)
>1s
VIH > 0.6*VBAT
PWRKEY
(INPUT)
VIL<0.1*VBAT
VDD_EXT
(OUTPUT)
800ms
STATUS
(OUTPUT)
MODULE
STATUS
OFF
BOOTING
RUNNING
Figure 8: Turn-on Timing
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GSM/GPRS Module Series
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NOTES
1. Make sure that VBAT is stable before pulling down PWRKEY pin. The time of T1 is recommended as
100ms.
2. EMERG_OFF should be floated when it is unused.
3. For more details about the application of STATUS pin, please refer to the Chapter 3.15.
3.4.2. Power Down
The following procedures can be used to turn off the module:




Normal power down procedure: Turn off module using the PWRKEY pin.
Normal power down procedure: Turn off module using command AT+QPOWD.
Over-voltage or under-voltage automatic shutdown: Take effect when over-voltage or under-voltage
is detected.
Emergent power down procedure: Turn off module using the EMERG_OFF pin.
3.4.2.1. Power Down Module Using the PWRKEY Pin
It is a safe way to turn off the module by driving the PWRKEY to a low level voltage for a certain time. The
power down scenario is illustrated as the following figure.
VBAT
0.7s4.6V or <3.3V, the module would
automatically shut down itself.
If the voltage is <3.3V, the following URC will be presented:
UNDER_VOLTAGE POWER DOWN
If the voltage is >4.6V, the following URC will be presented:
OVER_VOLTAGE POWER DOWN
After that moment, no further AT commands can be executed. The module logs off from network and
enters power down mode, and only RTC is still active.
NOTES
1. These unsolicited result codes do not appear when autobauding is active and DTE and DCE are not
correctly synchronized after start-up. The module is recommended to set to a fixed baud rate.
2. Over-voltage warning and shutdown function is disabled by default.
3.4.2.4. Emergency Shutdown Using EMERG_OFF Pin
The module can be shut down by driving the pin EMERG_OFF to a low level voltage over 40ms and then
releasing it. The EMERG_OFF line can be driven by an open-drain/collector driver or a button. The circuit
is illustrated as the following figures.
EMERG_OFF
4.7K
Emergency
shutdown pulse
47K
Figure 10: An Open-collector Driver for EMERG_OFF
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GSM/GPRS Module Series
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K2
EMERG_OFF
TVS2
Close to K2
Figure 11: Reference Circuit for EMERG_OFF by Using Button
Be cautious to use the pin EMERG_OFF. It should only be used under emergent situation. For instance, if
the module is unresponsive or abnormal, the pin EMERG_OFF could be used to shut down the system.
Although turning off the module by EMERG_OFF is fully tested and nothing wrong detected, this
operation is still a big risk as it could cause destroying of the code or data area of the flash memory in the
module. Therefore, it is recommended that PWRKEY or AT command should always be the preferential
way to turn off the system.
3.4.3. Restart
The module can be restarted by driving the PWRKEY to a low level voltage for a certain time, which is
similar to the way of turning on module. In order to make the internal LDOs discharge completely after
turning off the module, it is recommended to delay about 500ms before restarting the module. The restart
timing is illustrated as the following figure.
PWRKEY
(INPUT)
STATUS
(OUTPUT)
Turn off
Delay >500ms
Restart
Pull down the PWRKEY
to turn on the module
Figure 12: Timing of Restarting System
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The module can also be restarted by the PWRKEY after emergency shutdown.
EMERG_OFF
(INPUT)
Pulldown >40ms
Delay >500ms
STATUS
(OUTPUT)
PWRKEY
(INPUT)
Figure 13: Timing of Restarting System after Emergency Shutdown
NOTE
For more details about the application of STATUS pin, please refer to the Chapter 3.15.
3.5. Power Saving
Based on system requirements, there are several actions to drive the module to enter low current
consumption status. For example, AT+CFUN can be used to set module into minimum functionality mode
and DTR hardware interface signal can be used to lead system to SLEEP mode.
3.5.1. Minimum Functionality Mode
Minimum functionality mode reduces the functionality of the module to a minimum level. The consumption
of the current can be minimized when the slow clocking mode is activated at the same time. The mode is
set with the AT+CFUN command which provides the choice of the functionality levels =0, 1, 4.



0: minimum functionality
1: full functionality (default)
4: disable both transmitting and receiving of RF part
If the module is set to minimum functionality by AT+CFUN=0, the RF function and SIM card function
would be disabled. In this case, the UART port is still accessible, but all AT commands related with RF
function or SIM card function will be not available.
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If the module has been set by the command with AT+CFUN=4, the RF function will be disabled, but the
UART port is still active. In this case, all AT commands related with RF function will be not available.
After the module is set by AT+CFUN=0 or AT+CFUN=4, it can return to full functionality by AT+CFUN=1.
For detailed information about AT+CFUN, please refer to the document [1].
3.5.2. SLEEP Mode
The SLEEP mode is disabled by default. You can enable it by AT+QSCLK=1. On the other hand, the
default setting is AT+QSCLK=0 and in this mode, the module cannot enter SLEEP mode.
When the module is set by the command with AT+QSCLK=1, you can control the module to enter or exit
from the SLEEP mode through pin DTR. When DTR is set to high level, and there is no on-air or hardware
interrupt such as GPIO interrupt or data on UART port, the module will enter SLEEP mode automatically.
In this mode, the module can still receive voice, SMS or GPRS paging from network, but the UART port
does not work.
3.5.3. Wake up Module from SLEEP Mode
When the module is in the SLEEP mode, the following methods can wake up the module.



If the DTR Pin is set low, it would wake up the module from the SLEEP mode. The UART port will be
active within 20ms after DTR is changed to low level.
Receive a voice or GPRS data from network wakes up module.
Receive an SMS from network wakes up module.
NOTE
DTR pin should be held at low level during communication between the module and DTE.
3.5.4. Summary of State Transition
Table 5: Summary of State Transition
Next Mode
Current Mode
Power Down
Power Down
M85_Hardware_Design
Normal Mode
Sleep Mode
Use PWRKEY
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Normal Mode
SLEEP Mode
Use AT command
AT+QSCLK=1 and pull up
DTR
AT+QPOWD, use PWRKEY
pin, or use EMERG_OFF pin
Use PWRKEY pin, or use
EMERG_OFF pin
Pull DTR down or
incoming voice call or
SMS or GPRS data
transmission
3.6. RTC Backup
The RTC (Real Time Clock) function is supported. The RTC is designed to work with an internal power
supply.
There are three kinds of designs for RTC backup power:

Use VBAT as the RTC power source
When the module is turned off and the main power supply (VBAT) is remained, the real time clock is still
active as the RTC core is supplied by VBAT. In this case, the VRTC pin can be kept floating.

Use VRTC as the RTC power source
If the main power supply (VBAT) is removed after the module is turned off, a backup supply such as a
coin-cell battery (rechargeable or non-chargeable) or a super-cap can be used to supply the VRTC pin to
keep the real time clock active.

Use VBAT and VRTC as the RTC power source
As only power the VRTC pin to keep the RTC will lead an error about 5 minutes a day, it is recommended
to power VBAT and VRTC pin at the same time when RTC function is needed. The recommended supply
for RTC core circuits are shown as below.
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Module
RTC
Core
Power Supply
LDO/DCDC
VBAT
VRTC
LDO
1.5K
Non-chargeable
Backup Battery
Figure 14: VRTC is Supplied by a Non-chargeable Battery
Module
RTC
Core
Power Supply
LDO/DCDC
VBAT
VRTC
LDO
1.5K
Rechargeable
Backup Battery
Figure 15: VRTC is Supplied by a Rechargeable Battery
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Module
RTC
Core
Power Supply
LDO/DCDC
VBAT
VRTC
LDO
1.5K
Large Capacitance
Capacitor
Figure 16: VRTC is Supplied by a Capacitor
For the choice of a rechargeable or non-chargeable coin-cell battery, please visit http://www.sii.co.jp/en/.
NOTE
If you want to keep an accurate real time, please keep the main power supply VBAT alive.
3.7. Serial Interfaces
The module provides three serial ports: UART Port, Debug Port and Auxiliary Port. The module is
designed as a DCE (Data Communication Equipment), following the traditional DCE-DTE (Data Terminal
Equipment) connection. Autobauding function supports baud rate from 4800bps to 115200bps.
The UART Port:







TXD: Send data to RXD of DTE.
RXD: Receive data from TXD of DTE.
RTS: Request to send.
CTS: Clear to send.
DTR: DTE is ready and inform DCE (this pin can wake the module up).
RI: Ring indicator (when there is a call, SMS or URC output, the module will inform DTE with the RI
pin).
DCD: Data carrier detection (the validity of this pin demonstrates the communication link is set up).
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NOTE
Hardware flow control is disabled by default. When hardware flow control is required, RTS and CTS
should be connected to the host. AT command AT+IFC=2,2 is used to enable hardware flow control. AT
command AT+IFC=0,0 is used to disable the hardware flow control. For more details, please refer to the
document [1].
The Debug Port:


DBG_TXD: Send data to the COM port of computer.
DBG_RXD: Receive data from the COM port of computer.
The Auxiliary UART Port:


TXD_AUX: Send data to the RXD of DTE.
RXD_AUX: Receive data from the TXD of DTE.
The logic levels are described in the following table.
Table 6: Logic Levels of the UART Interface
Parameter
Min.
Max.
Unit
VIL
0.25×VDD_EXT
VIH
0.75×VDD_EXT
VDD_EXT +0.2
VOL
0.15×VDD_EXT
VOH
0.85×VDD_EXT
VDD_EXT
Pin Name
Pin No.
Description
DBG_RXD
43
Receive data
DBG_TXD
42
Transmit data
DCD
45
Data carrier detection
RI
46
Ring indication
Table 7: Pin Definition of the UART Interfaces
Interface
Debug Port
UART Port
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DTR
47
Data terminal ready
CTS
48
Clear to send
TXD
49
Transmit data
RXD
50
Receive data
RTS
51
Request to send
TXD_AUX
40
Transmit data
RXD_AUX
41
Receive data
Auxiliary UART Port
3.7.1. UART Port
3.7.1.1. The Features of UART Port





Contain data lines TXD and RXD, hardware flow control lines RTS and CTS, other control lines DTR,
DCD and RI.
Used for AT command, GPRS data, etc. Multiplexing function is supported on the UART Port. So far
only the basic mode of multiplexing is available.
Support the communication baud rates as the following:
300, 600, 1200, 2400, 4800, 9600, 14400, 19200, 28800, 38400, 57600 and 115200.
The default setting is autobauding mode. Support the following baud rates for autobauding function:
4800, 9600, 19200, 38400, 57600 and 115200.
The module disables hardware flow control by default. AT command AT+IFC=2,2 is used to enable
hardware flow control.
After setting a fixed baud rate or autobauding, please send AT string at that rate. The UART port is ready
when it responds OK.
Autobauding allows the module to detect the baud rate by receiving the string AT from the host or PC
automatically, which gives module flexibility without considering which baud rate is used by the host
controller. Autobauding is enabled by default. To take advantage of the autobauding mode, special
attention should be paid according to the following requirements:
1. Synchronization between DTE and DCE
When DCE (the module) powers on with the autobauding enabled, it is recommended to wait 4 or 5
seconds before sending the first AT character. After receiving the OK response, DTE and DCE are
correctly synchronized.
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If the host controller needs URC in the mode of autobauding, it must be synchronized firstly. Otherwise
the URC will be discarded.
2. Restrictions on autobauding operation






The UART port has to be operated at 8 data bits, no parity and 1 stop bit (factory setting).
Only the strings ―AT‖ or ―at‖ can be detected (neither ―At‖ nor ―aT‖).
The Unsolicited Result Codes like ―RDY‖, ―+CFUN: 1‖ and ―+CPIN: READY‖ will not be indicated
when the module is turned on with autobauding enabled and not be synchronized.
Any other Unsolicited Result Codes will be sent at the previous baud rate before the module detects
the new baud rate by receiving the first AT string. The DTE may receive unknown characters after
switching to new baud rate.
It is not recommended to switch to autobauding from a fixed baud rate.
If autobauding is active it is not recommended to switch to multiplex mode.
NOTE
To assure reliable communication and avoid any problems caused by undetermined baud rate between
DCE and DTE, it is strongly recommended to configure a fixed baud rate and save it instead of using
autobauding after start-up. For more details, please refer to the Section AT+IPR in document [1].
3.7.1.2. The Connection of UART Port
The connection between module and host using UART Port is very flexible. Three connection styles are
illustrated as below.
Reference design for Full-Function UART connection is shown as below when it is applied in
modulation-demodulation.
Module (DCE)
PC (DTE)
UART port
Serial port
TXD
RXD
RTS
CTS
DTR
DCD
TXD
RXD
RTS
CTS
DTR
DCD
RI
RING
GND
GND
Figure 17: Reference Design for Full-Function UART
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Three-line connection is shown as below.
Host (DTE)
Controller
Module (DCE)
UART port
TXD
TXD
RXD
RXD
GND
GND
0R
RTS
Figure 18: Reference Design for UART Port
UART Port with hardware flow control is shown as below. This connection will enhance the reliability of
the mass data communication.
Host (DTE)
Controller
Module (DCE)
TXD
TXD
RXD
RXD
RTS
RTS
CTS
CTS
GND
GND
Figure 19: Reference Design for UART Port with Hardware Flow Control
3.7.1.3. Firmware Upgrade
The TXD, RXD can be used to upgrade firmware. The PWRKEY pin must be pulled down before firmware
upgrade. The reference circuit is shown as below:
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Module (DCE)
IO Connector
UART port
TXD
TXD
RXD
RXD
GND
GND
PWRKEY
PWRKEY
Figure 20: Reference Design for Firmware Upgrade
NOTE
The firmware of module might need to be upgraded due to certain reasons. It is recommended to reserve
these pins in the host board for firmware upgrade.
3.7.2. Debug Port



Two lines: DBG_TXD and DBG_RXD
It outputs log information automatically.
Debug Port is only used for firmware debugging and its baud rate must be configured as 460800bps.
The reference design for Debug Port is shown as below.
Module
Peripheral
DBG_TXD
TXD
DBG_RXD
RXD
GND
GND
Figure 21: Reference Design for Debug Port
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3.7.3. Auxiliary UART Port





Two data lines: TXD_AUX and RXD_AUX.
Auxiliary UART port is used for AT command only and does not support GPRS data, multiplexing
function etc.
Auxiliary UART port supports the communication baud rates as the following:
1200, 2400, 4800, 9600, 14400, 19200, 28800, 38400, 57600, 115200bps.
Auxiliary UART port could be used when you send AT+QEAUART=1 string on the UART port.
The default baud rate setting is 115200bps, and does not support autobauding. The baud rate can be
modified by AT+QSEDCB command. For more details, please refer to the document [1].
Module
Peripheral
TXD_AUX
TXD
RXD_AUX
RXD
GND
GND
Figure 22: Reference Design for Auxiliary UART Port
3.7.4. UART Application
The reference design of 3.3V level match is shown as below. If the host is a 3V system, please change
the 5.6K resistor to 10K.
Module
Peripheral
/TXD
/RXD
/RTS
/CTS
GPIO
EINT
GPIO
1K
RXD
1K
TXD
1K
RTS
1K
CTS
1K
DTR
1K
RI
1K
DCD
GND
GND
5.6K
5.6K
5.6K
Voltage level:3.3V
Figure 23: Level Match Design for 3.3V System
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NOTE
It is highly recommended to add the resistor divider circuit on the UART signal lines when the host’s level
is 3V or 3.3V. For the higher voltage level system, a level shifter IC could be used between the host and
the module. For more details about UART circuit design, please refer to document [11].
The following figure shows a sketch map between module and standard RS-232 interface. Since the
electrical level of module is 2.8V, so a RS-232 level shifter must be used. Note that you should assure the
IO voltage of level shifter which connects to module is 2.8V.
C1+
V+
GND
C1-
GND
GND
C2+
VCC
C2-
V-
3.3V
Module
1K
DCD
1K
TXD
1K
CTS
1K
RI
T1IN
T2OUT
T2IN
T1OUT
T3IN
T5OUT
T4IN
T3OUT
T5IN
T4OUT
GND
1K
RXD
1K
DTR
1K
RTS
/R1OUT
5.6K
R1OUT
R1IN
R2OUT
R2IN
R3OUT
R3IN
GND
GND
5.6K
5.6K
RS-232 Level Shifter
To PC Serial Port
Figure 24: Sketch Map for RS-232 Interface Match
Please visit vendor website to select the suitable RS-232 level shifter IC, such as: http://www.exar.com/
and http://www.maximintegrated.com.
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3.8. Audio Interfaces
The module provides two analogy input channels and three analogy output channels.
Table 8: Pin Definition of Audio Interface
Interface
Pin Name
Pin No.
Description
MIC1P
Channel 1 Microphone positive input
MIC1N
10
Channel 1 Microphone negative input
SPK1P
12
Channel 1 Audio positive output
SPK1N
11
Channel 1 Audio negative output
MIC2P
Channel 2 Microphone positive input
MIC2N
Channel 2 Microphone negative input
SPK2P
Channel 2 Audio positive output
AGND
Form a pseudo-differential pair with SPK2P
LOUDSPKP
14
Channel 3 Audio positive output
LOUDSPKN
13
Channel 3 Audio negative output
AIN1/AOUT1
AIN2/AOUT2
AOUT3
AIN1 and AIN2 can be used for input of microphone and line. An electret microphone is usually used.
AIN1 and AIN2 are both differential input channels.
AOUT1 is used for output of the receiver. This channel is typically used for a receiver built into a handset.
AOUT1 channel is a differential channel.
AOUT2 is typically used with earphone. It is a single-ended and mono channel. SPK2P and AGND can
establish a pseudo differential mode.
AOUT2 can also be used for output of receiver, which can be used as a single-ended channel. SPK2P
and AGND can establish a pseudo differential mode.
AOUT3 is used for loud speaker output as it embedded an amplifier of class AB whose maximum drive
power is 870mW.
All of these three audio channels support voice and ringtone output, and so on, and can be switched by
AT+QAUDCH command. For more details, please refer to the document [1].
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Use AT command AT+QAUDCH to select audio channel:



0--AIN1/AOUT1, the default value is 0.
1--AIN2/AOUT2
2--AIN2/AOUT3
For each channel, you can use AT+QMIC to adjust the input gain level of microphone. Customer can also
use AT+CLVL to adjust the output gain level of receiver and speaker. AT+QSIDET is used to set the
side-tone gain level. For more details, please refer to the document [1].
Table 9: AOUT3 Output Characteristics
Item
RMS Power
Condition
Min.
Type
Max.
Unit
8ohm load
VBAT=4.2V
THD+N=1%
870
mW
8ohm load
VBAT=3.3V
THD+N=1%
530
mW
3.8.1. Decrease TDD Noise and Other Noise
The 33pF capacitor is applied for filtering out 900MHz RF interference when the module is transmitting at
EGSM900MHz. Without placing this capacitor, TDD noise could be heard. Moreover, the 10pF capacitor
here is for filtering out 1800MHz RF interference. However, the resonant frequency point of a capacitor
largely depends on the material and production technique. Therefore, you would have to discuss with its
capacitor vendor to choose the most suitable capacitor for filtering out GSM850MHz, EGSM900MHz,
DCS1800MHz and PCS1900MHz separately.
The severity degree of the RF interference in the voice channel during GSM transmitting period largely
depends on the application design. In some cases, GSM900 TDD noise is more severe; while in other
cases, DCS1800 TDD noise is more obvious. Therefore, you can have a choice based on test results.
Sometimes, even no RF filtering capacitor is required.
The capacitor which is used for filtering out RF noise should be close to audio interface. Audio alignment
should be as short as possible.
In order to decrease radio or other signal interference, the position of RF antenna should be kept away
from audio interface and audio alignment. Power alignment and audio alignment should not be parallel,
and power alignment should be far away from audio alignment.
The differential audio traces have to be placed according to the differential signal layout rule.
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3.8.2. Microphone Interfaces Design
AIN1 and AIN2 channels come with internal bias supply for external electret microphone. A reference
circuit is shown in the following figure.
Close to
Microphone
GND
Differential
layout
GND
GND
10pF
0603
33pF
0603
10pF
0603
33pF
0603
10pF
0603
33pF
0603
ESD
MICxP
Module
MICxN
GND
Electret
Microphone
ESD
GND
GND
Figure 25: Reference Design for AIN1&AIN2
3.8.3. Receiver and Speaker Interface Design
Close to speaker
GND
Differential layout
10pF
0603
33pF
0603
10pF
0603
33pF
0603
10pF
0603
33pF
0603
ESD
Module
SPK1P
SPK1N
ESD
GND
Figure 26: Handset Interface Design for AOUT1
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Close to speaker
GND
Differential
layout
10pF
0603
33pF
0603
10pF
0603
33pF
0603
10pF
0603
33pF
0603
ESD
Amplifier
circuit
SPK1P
Module
SPK1N
ESD
GND
Figure 27: Speaker Interface Design with an Amplifier for AOUT1
Close to Speaker
GND
Differential layout
SPK2P
Module
10pF
0603
33pF
0603
ESD
22uF
AGND
Figure 28: Handset Interface Design for AOUT2
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Close to Speaker
GND
Differential layout
Amplifier
circuit
10pF
0603
33pF
0603
10pF
0603
33pF
0603
ESD
C1
SPK2P
Module
AGND
C2
ESD
GND
Figure 29: Speaker Interface Design with an Amplifier for AOUT2
The suitable differential audio amplifier can be chosen from the Texas Instrument’s website
(http://www.ti.com/). There are other excellent audio amplifier vendors in the market too.
4.NOTE
The value of C1 and C2 here depends on the input impedance of audio amplifier.
3.8.4. Earphone Interface Design
Close to Socket
Differential
layout
GND
4.7uF
10pF
0603
MIC2N
MIC2P
33pF
0603
ESD
68R
Module
22uF
SPK2P
AGND
10pF
0603
33pF
0603
ESD
AGND
AGND
GND
Figure 30: Earphone Interface Design
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3.8.5. Loud Speaker Interface Design
Close to Speaker
GND
Differential layout
10pF
0603
33pF
0603
0R
ESD
LOUDSPKP
Module
100pF
0R
LOUDSPKN
10pF
0603
33pF
0603
ESD
GND
Figure 31: Loud Speaker Interface Design
3.8.6. Audio Characteristics
Table 10: Typical Electret Microphone Characteristics
Parameter
Min.
Typ.
Max.
Unit
Working Voltage
1.2
1.5
2.0
Working Current
200
500
uA
External Microphone Load Resistance
2.2
kΩ
Table 11: Typical Speaker Characteristics
Parameter
Min.
Load resistance
Typ.
Max.
32
Unit
Ohm
Single-ended
Ref level
AOUT1
Output
Load resistance
2.4
32
Vpp
Ohm
Differential
Ref level
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AOUT2
Output
AOUT3
Output
Load resistance
32
Ohm
Single-ended
Ref level
Load resistance
2.4
Vpp
Ohm
Differential
Ref level
2×VBAT
Vpp
3.9. SIM Card Interfaces
The module contains two SIM interfaces to allow module access the two SIM cards. Only one SIM card
can work at a time. Both of two SIM interfaces share the ground and only first SIM interface have card
insert detection.
In dual SIM card mode, configure AT+QDSIM=0 to use the SIM1 interface and configure AT+QDSIM=1 to
use SIM2 interface. For more details, please refer to the document [1].
The SIM interface supports the functionality of the GSM Phase 1 specification and also supports the
functionality of the new GSM Phase 2+ specification for FAST 64 kbps SIM card, which is intended for
use with a SIM application Tool-kit.
The SIM interface is powered by an internal regulator in the module. Both 1.8V and 3.0V SIM Cards are
supported.
Table 12: Pin Definition of the SIM Interface
Pin Name
Pin No.
Description
SIM1_VDD
56
SIM2_VDD
71
Supply power for SIM card. Automatic detection of SIM
card voltage. 3.0V±10% and 1.8V±10%. Maximum
supply current is around 10mA.
SIM1_CLK
55
SIM card clock
SIM2_CLK
72
SIM1_DATA
54
SIM2_DATA
73
SIM1_RST
53
SIM card data I/O
SIM card reset
SIM2_RST
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SIM1_PRESENCE
57
SIM1 card detection
SIM_GND
52
SIM card ground
The following figure is the reference design for SIM interface, and here an 8-pin SIM card holder is used.
The pin SIM1_PRESENCE is used to detect whether the tray of the Molex SIM socket, which is used for
holding SIM card, is present in the card socket. When the tray is inserted in the socket, SIM1_PRESENCE
is at low level. Regardless of the SIM card is in the tray or not, the change of SIM1_PRESENCE level from
high to low level prompts the module to reinitialize SIM card. In default configuration, SIM card detection
function is disabled. Your application can use AT+QSIMDET=1,0 and AT+QSIMDET=0,0 to switch on and
off the SIM card detection function. For details of this AT command, please refer to document [1]. When
AT+QSIMDET=1,0 is set and the tray with SIM card is removed from SIM socket, the following URC will be
presented:
+CPIN: NOT INSERTED
When the tray with SIM card is inserted into SIM socket again and the module finishes reinitializing SIM
card, the following URC will be presented:
+CPIN: READY
Call Ready
VDD_EXT
10K
SIM_GND
Module
100nF
SIM1_VDD
SIM1_RST
SIM1_CLK
SIM1_PRESENCE
SIM1_DATA
SIM_Holder
VCC
RST
22R
22R
CLK
GND
VPP
IO
22R
GND
33pF 33pF33pF33pF
TVS
GND
GND
Figure 32: Reference Circuit for SIM1 Interface with 8-pin SIM Card Holder
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If the SIM1 card detection function is not used, keep SIM1_PRESENCE pin open. The reference circuit
for a 6-pin SIM card socket is illustrated as the following figure.
SIM_GND
Module
100nF
SIM1_VDD
SIM1_RST
SIM1_CLK
SIM1_PRESENCE
SIM1_DATA
SIM_Holder
VCC
RST
CLK
22R
22R
GND
VPP
IO
22R
33pF33pF 33pF 33pF
TVS
GND
GND
Figure 33: Reference Circuit for SIM1 Interface with the 6-pin SIM Card Holder
The following figure is the reference design for SIM2 interface with the 6-pin SIM card holder.
SIM_GND
Module
100nF
SIM2_VDD
SIM2_RST
SIM2_CLK
SIM_Holder
VCC
RST
CLK
22R
22R
SIM2_DATA
GND
VPP
IO
22R
33pF33pF 33pF 33pF
TVS
GND
GND
Figure 34: Reference Circuit for SIM2 Interface with the 6-pin SIM Card Holder
For more information
http://www.molex.com.
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In order to enhance the reliability and availability of the SIM card in application. Please follow the below
criteria in the SIM circuit design:






Keep layout of SIM card as close as possible to the module. Assure the length of the trace as less
than 200mm as possible.
Keep SIM card signals away from RF and VBAT alignment.
Assure the ground between module and SIM cassette short and wide. Keep the width of ground no
less than 0.5mm to maintain the same electric potential. The decouple capacitor of SIM_VDD is less
than 1uF and must be near to SIM cassette.
To avoid cross talk between SIM_DATA and SIM_CLK. Keep them away with each other and shield
them with surrounded ground.
In order to offer good ESD protection, it is recommended to add a TVS diode array. For more
information of TVS diode, please visit http://www.onsemi.com/.The most important rule is to place the
ESD protection device close to the SIM card socket and make sure the nets being protected will go
through the ESD device first and then lead to module. The 22Ω resistors should be connected in
series between the module and the SIM card so as to suppress the EMI spurious transmission and
enhance the ESD protection. Please to be noted that the SIM peripheral circuit should be close to the
SIM card socket.
Place the RF bypass capacitors (33pF) close to the SIM card on all signal lines for improving EMI.
3.10. SD Card Interface
The module provides SD card interface that supports many types of memory, such as Memory Stick,
SD/MCC card and T-Flash or Micro SD card. The following are the main features of SD card interface.






Only supports 1bit serial mode.
Not support the SPI mode for SD memory card.
Not support multiple SD memory cards.
Not support hot plug.
The data rate up to 48MHz in serial mode.
Up to 32GB maximum memory card capacity.
With the SD card interface features and reference circuit shown as below, you can easily design the SD
card application circuit to enhance the memory capacity of the module. The users can store some
high-capacity files to external memory card. Such as in the automotive application system, the module
can record and store the audio file to the SD card, and also can play the audio files in SD card.
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Table 13: Pin Definition of the SD Card Interface
Pin Name
Pin No.
Description
SD_CMD
34
Command signal of SD card output
SD_CLK
35
Clock signal of SD card output
SD_DATA0
36
Data output and input signal of SD card
VDD_EXT
47K 47K
33R
SD_CMD
33R
SD_CLK
33R
SD_DATA0
SD Socket
47K
Module
4.7uF
DATA2
CD/DATA3
CMD
VSS1
VDD
CLK
VSS2
DATA0
DATA1
0.1nF
Figure 35: Reference Circuit for SD Card
Table 14: Pin Definition of the SD Card Interface
Pin No.
Pin Name of SD Card
Pin Name of T-Flash (Micro SD) Card
CD/DATA3
DATA2
CMD
CD/DATA3
VSS1
CMD
VDD
VDD
CLK
CLK
VSS2
VSS
DATA0
DATA0
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DATA1
DATA2
DATA1
In SD card interface designing, in order to ensure good communication performance with SD card, the
following design principles should be complied with:






Keep all the SD card signals far away from VBAT power and RF trace.
Route all SD card signals as short as possible. Ensure the length of every trace does not exceed
10cm.
The SD_CLK, SD_DATA0 and SD_CMD trace should be routed together. Keep trace difference of
SD_DATA0, SD_CMD and SD_CLK to be less than 10mm.
In order to offer good ESD protection, it is recommended to add TVS on signals with the capacitance
less than 15pF.
Reserve external pull-up resistors for other data lines except the DATA0 signal.
The SD_CLK and SD_DATA0 line must be shielded by ground in order to improve EMI.
3.11. PCM Interface
M85 supports PCM interface. It is used for digital audio transmission between the module and the device.
This interface is composed of PCM_CLK, PCM_SYNC, PCM_IN and PCM_OUT signal lines.
Pulse-code modulation (PCM) is a converter that changes the consecutive analog audio signal to discrete
digital signal. The whole procedure of Pulse-code modulation contains sampling, quantizing and
encoding.
Table 15: Pin Definition of PCM Interface
Pin Name
Pin No.
Description
PCM_IN
18
PCM data input
PCM_CLK
19
PCM clock output
PCM_OUT
20
PCM data output
PCM_SYNC
21
PCM frame synchronization output
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3.11.1. Configuration
M85 module supports 13-bit line code PCM format. The sample rate is 8 KHz, and the clock source is 256
KHz, and the module can only act as master mode. The PCM interface supports both long and short
synchronization simultaneously. Furthermore, it only supports MSB first. For detailed information, please
refer to the table below.
Table 16: Configuration
PCM
Line Interface Format
Linear
Data Length
Linear: 13 bits
Sample Rate
8KHz
PCM Clock/Synchronization Source
PCM master mode: clock and synchronization is
generated by module
PCM Synchronization Rate
8KHz
PCM Clock Rate
PCM master mode: 256 KHz (line)
PCM Synchronization Format
Long/short synchronization
PCM Data Ordering
MSB first
Zero Padding
Yes
Sign Extension
Yes
3.11.2. Timing
The sample rate of the PCM interface is 8 KHz and the clock source is 256 KHz, so every frame contains
32 bits data, since M85 supports 16 bits line code PCM format, the left 16 bits are invalid. The following
diagram shows the timing of different combinations. The synchronization length in long synchronization
format can be programmed by firmware from one bit to eight bits. In the Sign extension mode, the high
three bits of 16 bits are sign extension, and in the Zero padding mode, the low three bits of 16 bits are
zero padding.
Under zero padding mode, you can configure the PCM input and output volume by executing
AT+QPCMVOL command. For more details, please refer to Chapter 3.11.4.
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PCM_CLK
PCM_SYNC
MSB
PCM_OUT
Sign
extension
12 11 10
12 11 10 9
MSB
PCM_IN
Sign
extension
Figure 36: Long Synchronization & Sign Extension Diagram
PCM_CLK
PCM_SYNC
MSB
PCM_OUT
12 11 10 9
Zero padding
Zero padding
MSB
PCM_IN
12 11 10 9
Figure 37: Long Synchronization & Zero Padding Diagram
PCM_CLK
PCM_SYNC
MSB
PCM_OUT
Sign extension
12 11 10
12 11 10
MSB
PCM_IN
Sign extension
Figure 38: Short synchronization & Sign Extension Diagram
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PCM_CLK
PCM_SYNC
MSB
PCM_OUT
12 11 10
0 Zero padding
0 Zero padding
MSB
PCM_IN
12 11 10
Figure 39: Short Synchronization & Zero Padding Diagram
3.11.3. Reference Design
M85 can only work as a master, providing synchronization and clock source. The reference design is
shown as below.
Peripheral
(Slave)
Module
(Master)
PCM_CLK
PCM_CLK
PCM_SYNC
PCM_SYNC
PCM_OUT
PCM_IN
PCM_OUT
PCM_IN
Figure 40: Reference Design for PCM
3.11.4. AT Command
There are two AT commands about the configuration of PCM are listed as below.
AT+QPCMON can configure operating mode of PCM.
AT+QPCMON= mode,Sync_Type,Sync_Length,SignExtension,MSBFirst.
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Table 17: QPCMON Command Description
Parameter
Scope
Description
Mode
0~2
0: Close PCM
1: Open PCM
2: Open PCM when audio talk is set up
Sync_Type
0~1
0: Short synchronization
1: Long synchronization
Sync_Length
1~8
Programmed from one bit to eight bit
SignExtension
0~1
0: Zero padding
1: Sign extension
MSBFirst
0~1
0: MSB first
1: Not supported
AT+QPCMVOL can configure the volume of input and output.
AT+QPCMVOL=vol_pcm_in, vol_pcm_out
Table 18: QPCMVOL Command Description
Parameter
Scope
Description
vol_pcm_in
0~32767
Set the input volume
vol_pcm_out
0~32767
Set the output volume
The voice may be distorted when this value exceeds 16384.
3.12. ADC
The module provides an ADC channel to measure the value of voltage. Please give priority to the use of
ADC0 channel. The command AT+QADC can read the voltage value applied on ADC0 pin. For details of
this AT command, please refer to the document [1]. In order to improve the accuracy of ADC, the layout
of ADC should be surrounded by ground.
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Table 19: Pin Definition of the ADC
Pin Name
Pin No.
Description
ADC0
Analog to digital converter.
Table 20: Characteristics of the ADC
Item
Min.
Voltage Range
Typ.
Max.
Units
2.8
ADC Resolution
10
bits
ADC Accuracy
2.7
mV
3.13. Behaviors Of The RI
Table 21: Behaviors of the RI
State
RI response
Standby
HIGH
Voice Calling
Change to LOW, then:
1. Change to HIGH when call is established.
2. Use ATH to hang up the call, RI changes to HIGH.
3. Calling part hangs up, RI changes to HIGH first, and changes to LOW for
120ms indicating ―NO CARRIER‖ as an URC, then changes to HIGH again.
4. Change to HIGH when SMS is received.
SMS
When a new SMS comes, the RI changes to LOW and holds low level for about 120
ms, then changes to HIGH.
URC
Certain URCs can trigger 120ms low level on RI.
NOTE
If URC of SMS is disabled, the RI will not change.
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If the module is used as a caller, the RI would maintain high except the URC or SMS is received. On the
other hand, when it is used as a receiver, the timing of the RI is shown as below.
RI
HIGH
Off-hook by“ATA”
On-hook by “ATH”
LOW
Idle
SMS received
Ring
Figure 41: RI Behavior of Voice Calling as a Receiver
HIGH
RI
LOW
Idle
Calling
Talking
On-hook
Idle
Figure 42: RI Behavior as a Caller
HIGH
RI
120ms
LOW
Idle or
Talking
URC or
SMS received
Figure 43: RI Behavior of URC or SMS Received
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3.14. Network Status Indication
The NETLIGHT signal can be used to drive a network status indicator LED. The working state of this pin
is listed in the following table.
Table 22: Working State of the NETLIGHT
State
Module function
Off
The module is not running.
64ms On/800ms Off
The module is not synchronized with network.
64ms On/2000ms Off
The module is synchronized with network.
64ms On/600ms Off
The GPRS data transmission after dialing the PPP connection.
A reference circuit is shown as below.
VBAT
Module
300R
4.7K
NETLIGHT
47K
Figure 44: Reference Design for NETLIGHT
3.15. Operating Status Indication
The STATUS pin will output a high level after the module being turned on, but it is not recommended
connecting this pin to a MCU’s GPIO to judge whether the module is turn-on or not. The following LED
indicator circuit for STATUS pin can be used to indicate the state after the module has been turned on.
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Table 23: Pin Definition of the STATUS
Pin Name
Pin No.
Description
STATUS
16
Indicate module operating status
VBAT
300R
Module
4.7K
STATUS
47K
Figure 45: Reference Design for STATUS
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Antenna Interface
The Pin 63 is the RF antenna pad. The RF interface has an impedance of 50Ω.
Table 24: Pin Definition of the RF_ANT
Pin Name
Pin No.
Description
GND
61
Ground
GND
62
Ground
RF_ANT
63
RF antenna pad
GND
64
Ground
GND
65
Ground
GND
66
Ground
4.1. Reference Design
The external antenna must be matched properly to achieve best performance, so the matching circuit is
necessary, the reference design for RF is shown as below.
0R
RF_ANT
Module
NM
NM
Figure 46: Reference Design for RF
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M85 provides an RF antenna pad for antenna connection. The RF trace in host PCB connected to the
module RF antenna pad should be coplanar waveguide line or microstrip line, whose characteristic
impedance should be close to 50Ω. M85 comes with grounding pads which are next to the antenna pad in
order to give a better grounding. Besides, a π type match circuit is suggested to be used to adjust the RF
performance.
4.2. RF Output Power
Table 25: The Module Conducted RF Output Power
Frequency
Max.
Min.
GSM850
33dBm±2dB
5dBm±5dB
EGSM900
33dBm±2dB
5dBm±5dB
DCS1800
30dBm±2dB
0dBm±5dB
PCS1900
30dBm±2dB
0dBm±5dB
NOTE
In GPRS 4 slots TX mode, the max output power is reduced by 2.5dB. This design conforms to the GSM
specification as described in Section 13.16 of 3GPP TS 51.010-1.
4.3. RF Receiving Sensitivity
Table 26: The Module Conducted RF Receiving Sensitivity
Frequency
Receive Sensitivity
GSM850
< -109dBm
EGSM900
< -109dBm
DCS1800
< -109dBm
PCS1900
< -109dBm
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4.4. Operating Frequencies
Table 27: The Module Operating Frequencies
Frequency
Receive
Transmit
ARFCH
GSM850
869~894MHz
824~849MHz
128~251
EGSM900
925~960MHz
880~915MHz
0~124, 975~1023
DCS1800
1805~1880MHz
1710~1785MHz
512~885
PCS1900
1930~1990MHz
1850~1910MHz
512~810
4.5. Antenna Requirement
The following table shows the requirement on GSM antenna.
Table 28: Antenna Cable Requirements
Type
Requirements
GSM850/EGSM900
Cable insertion loss <1dB
DCS1800/PCS1900
Cable insertion loss <1.5dB
Table 29: Antenna Requirements
Type
Requirements
Frequency Range
GSM850/EGSM900/DCS1800/PCS1900MHz.
VSWR
≤2
Gain (dBi)
Max Input Power (W)
50
Input Impedance (Ω)
50
Polarization Type
Vertical
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4.6. RF Cable Soldering
Soldering the RF cable to RF pad of module correctly will reduce the loss on the path of RF, please refer
to the following example of RF soldering.
Figure 47: RF Soldering Sample
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Electrical, Reliability and Radio
Characteristics
5.1. Absolute Maximum Ratings
Absolute maximum ratings for power supply and voltage on digital and analog pins of module are listed in
the following table:
Table 30: Absolute Maximum Ratings
Parameter
Min.
Max.
Unit
VBAT
-0.3
+4.73
Peak current of power supply
RMS current of power supply (during one TDMA- frame)
0.7
Voltage at digital pins
-0.3
3.08
Voltage at analog pins
-0.3
3.08
Voltage at digital/analog pins in power down mode
-0.25
0.25
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5.2. Operating Temperature
The operating temperature is listed in the following table:
Table 31: Operating Temperature
Parameter
Min.
Typ.
Max.
Unit
Normal Temperature
-35
+25
+80
℃
Restricted Operation1)
-40 ~ -35
+80 ~ +85
℃
Storage Temperature
-45
+90
℃
NOTE
1)
When the module works within this temperature range, the deviation from the GSM specification may
occur. For example, the frequency error or the phase error will be increased.
5.3. Power Supply Ratings
Table 32: The Module Power Supply Ratings
Parameter
VBAT
IVBAT
Description
Conditions
Min.
Typ.
Max.
Unit
Supply voltage
Voltage must stay within the
min/max values, including
voltage drop, ripple, and
spikes.
3.3
4.0
4.6
Voltage drop
during
transmitting
burst
Maximum power control level
on GSM850 and EGSM900.
400
mV
Average supply
current
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Power down mode
SLEEP mode @DRX=5
150
1.3
uA
mA
Minimum functionality mode
AT+CFUN=0
IDLE mode
SLEEP mode
13
0.98
mA
mA
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Peak supply
current (during
transmission
slot)
AT+CFUN=4
IDLE mode
SLEEP mode
13
1.0
mA
mA
TALK mode
GSM850/EGSM9001)
DCS1800/PCS19002)
223/219
153/151
mA
mA
DATA mode, GPRS (3Rx,2Tx)
GSM850/EGSM9001)
DCS1800/PCS19002)
363/393
268/257
mA
mA
DATA mode, GPRS (2Rx,3Tx)
GSM850/EGSM9001)
DCS1800/PCS19002)
506/546
366/349
mA
mA
DATA mode, GPRS (4Rx,1Tx)
GSM850/EGSM9001)
DCS1800/PCS19002)
217/234
172/170
mA
mA
DATA mode, GPRS (1Rx,4Tx)
GSM850/EGSM9001)
DCS1800/PCS19002)
458/4853)
462/439
mA
mA
Maximum power control level
on GSM850 and EGSM900.
1.6
NOTES
1.
2.
3.
1)
Power control level PCL 5.
Power control level PCL 0.
3)
Under the GSM850 and EGSM900 spectrum, the power of 1Rx and 4Tx has been reduced.
2)
5.4. Current Consumption
The values of current consumption are shown as below.
Table 33: The Module Current Consumption
Condition
Current Consumption
Voice Call
GSM850
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@power level #12, Typical 83mA
@power level #19, Typical 62mA
EGSM900
@power level #5 <300mA, Typical 219mA
@power level #12, Typical 83mA
@power level #19, Typical 63mA
DCS1800
@power level #0 <250mA, Typical 153mA
@power level #7, Typical 73mA
@power level #15, Typical 60mA
PCS1900
@power level #0 <250mA, Typical 151mA
@power level #7, Typical 76mA
@power level #15, Typical 61mA
GPRS Data
DATA Mode, GPRS (3Rx, 2Tx) CLASS 12
GSM850
@power level #5 <550mA, Typical 363mA
@power level #12, Typical 131mA
@power level #19, Typical 91mA
EGSM900
@power level #5 <550mA, Typical 393mA
@power level #12, Typical 132mA
@power level #19, Typical 92mA
DCS1800
@power level #0 <450mA, Typical 268mA
@power level #7, Typical 112mA
@power level #15, Typical 88mA
PCS1900
@power level #0 <450mA, Typical 257mA
@power level #7, Typical 119mA
@power level #15, Typical 89mA
DATA Mode, GPRS (2Rx, 3Tx) CLASS 12
GSM850
@power level #5 <640mA, Typical 506mA
@power level #12, Typical 159mA
@power level #19, Typical 99mA
EGSM900
@power level #5 <600mA, Typical 546mA
@power level #12, Typical 160mA
@power level #19, Typical 101mA
DCS1800
@power level #0 <490mA, Typical 366mA
@power level #7, Typical 131mA
@power level #15, Typical 93mA
PCS1900
@power level #0 <480mA, Typical 348mA
@power level #7, Typical 138mA
@power level #15, Typical 94mA
DATA Mode, GPRS (4Rx, 1Tx) CLASS 12
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GSM850
@power level #5 <350mA, Typical 216mA
@power level #12, Typical 103mA
@power level #19, Typical 83mA
EGSM900
@power level #5 <350mA, Typical 233mA
@power level #12, Typical 104mA
@power level #19, Typical 84mA
DCS1800
@power level #0 <300mA, Typical 171mA
@power level #7, Typical 96mA
@power level #15, Typical 82mA
PCS1900
@power level #0 <300mA, Typical 169mA
@power level #7, Typical 98mA
@power level #15, Typical 83mA
DATA Mode, GPRS (1Rx, 4Tx) CLASS 12
GSM850
@power level #5 <660mA, Typical 457mA
@power level #12, Typical 182mA
@power level #19, Typical 106mA
EGSM900
@power level #5 <660mA, Typical 484mA
@power level #12, Typical 187mA
@power level #19, Typical 109mA
DCS1800
@power level #0 <530mA, Typical 461mA
@power level #7, Typical 149mA
@power level #15, Typical 97mA
PCS1900
@power level #0 <530mA, Typical 439mA
@power level #7, Typical 159mA
@power level #15, Typical 99mA
NOTE
GPRS Class 12 is the default setting. The module can be configured from GPRS Class 1 to Class 12.
Setting to lower GPRS class would make it easier to design the power supply for the module.
5.5. Electro-static Discharge
Although the GSM engine is generally protected against Electro-static Discharge (ESD), ESD protection
precautions should still be emphasized. Proper ESD handling and packaging procedures must be applied
throughout the processing, handling and operation of any applications using the module.
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The measured ESD values of module are shown as the following table:
Table 34: The ESD Endurance (Temperature: 25ºC, Humidity: 45%)
Tested Point
Contact Discharge
Air Discharge
VBAT, GND
±5KV
±10KV
RF_ANT
±5KV
±10KV
TXD, RXD
±2KV
±4KV
Others
±0.5KV
±1KV
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Mechanical Dimensions
This chapter describes the mechanical dimensions of the module.
6.1. Mechanical Dimensions of Module
Figure 48: M85 Module Top and Side Dimensions (Unit: mm)
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Figure 49: M85 Module Bottom Dimensions (Unit: mm)
Figure 50: The PAD Dimensions (Unit: mm)
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6.2. Recommended Footprint
Figure 51: Recommended Footprint (Unit: mm)
NOTE
The module should keep about 3mm away from other components in the host PCB.
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6.3. Top View of the Module
Figure 52: Top View of the Module
6.4. Bottom View of the Module
Figure 53: Bottom View of the Module
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Storage and Manufacturing
7.1. Storage
M85 module is distributed in a vacuum-sealed bag. The restriction for storage is shown as below.
Shelf life in the vacuum-sealed bag: 12 months at environments of <40ºC temperature and < 90%RH.
After the vacuum-sealed bag is opened, devices that need to be mounted directly must be:


Mounted within 72 hours at the factory environment of ≤30ºC temperature and <60% RH.
Stored at <10% RH.
Devices require baking before mounting, if any circumstance below occurs.



When the ambient temperature is 23ºC±5ºC, humidity indication card shows the humidity is >10%
before opening the vacuum-sealed bag.
If ambient temperature is <30ºC and the humidity is <60%, the devices have not been mounted
during 72hours.
Stored at >10% RH.
If baking is required, devices should be baked for 48 hours at 125ºC±5ºC.
NOTE
As plastic container cannot be subjected to high temperature, devices must be removed prior to high
temperature (125ºC) bake. If shorter bake times are desired, refer to the IPC/JEDECJ-STD-033 for bake
procedure.
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7.2. Soldering
The squeegee should push the paste on the surface of the stencil that makes the paste fill the stencil
openings and penetrate to the PCB. The force on the squeegee should be adjusted so as to produce a
clean stencil surface on a single pass. To ensure the module soldering quality, the thickness of stencil at
the hole of the module pads should be 0.2 mm for M85. For more details, please refer to document [13].
It is suggested that peak reflow temperature is from 235ºC to 245ºC (for SnAg3.0Cu0.5 alloy). Absolute
max reflow temperature is 260ºC. To avoid damage to the module when it was repeatedly heated, it is
suggested that the module should be mounted after the first panel has been reflowed. The following
picture is the actual diagram which we have operated.
℃
Preheat
Heating
Cooling
250
Liquids
Temperature
217
200℃
200
40s~60s
160℃
150
70s~120s
100
Between 1~3℃/S
50
50
100
150
200
250
300
Time(s)
Figure 54: Ramp-Soak-Spike Reflow Profile
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7.3. Packaging
M85 modules are shipped in tape and reel form. The reel is 330mm in diameter and each reel contains
250pcs modules. This is especially suitable for the M85 according to SMT assembly processes
requirements.
The tape is packed in a vacuum-sealed bag which is ESD protected. Furthermore, it should not be
opened until the devices are ready to be soldered onto the application.
Direction of SMT
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DETAIL:A
PS
DC圆盘44
DETAIL:A
Figure 55: Tape and Reel Information
Table 35: Reel Packing
Model Name
M85
MOQ for MP
Minimum Package: 250pcs
Minimum Package×4=1000pcs
250pcs
Size: 370 × 350 × 56mm
N.W: 0.78kg
G.W: 1.54kg
Size: 380 × 250 × 365mm
N.W: 3.10kg
G.W: 6.80kg
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M85 Hardware Design
Appendix A Reference
Table 36: Related Documents
SN
Document Name
Remark
[1]
Quectel_M85_AT_Commands_Manual
AT commands manual
[2]
ITU-T Draft new recommendation V.25ter
Serial asynchronous automatic dialing and
control
[3]
GSM 07.07
Digital cellular telecommunications (Phase
2+); AT command set for GSM Mobile
Equipment (ME)
[4]
GSM 07.10
Support GSM 07.10 multiplexing protocol
GSM 07.05
Digital cellular telecommunications (Phase
2+); Use of Data Terminal Equipment – Data
Circuit terminating Equipment (DTE – DCE)
interface for Short Message Service (SMS)
and Cell Broadcast Service (CBS)
GSM 11.14
Digital cellular telecommunications (Phase
2+); Specification of the SIM Application
Toolkit for the Subscriber Identity module –
Mobile Equipment (SIM – ME) interface
GSM 11.11
Digital cellular telecommunications (Phase
2+); Specification of the Subscriber Identity
module – Mobile Equipment (SIM – ME)
interface
GSM 03.38
Digital cellular telecommunications (Phase
2+); Alphabets and language-specific
information
[9]
GSM 11.10
Digital cellular telecommunications (Phase
2); Mobile Station (MS) conformance
specification;
Part
1:
Conformance
specification
[10]
Quectel_GSM_UART_Application_Note
UART port application note
[11]
Quectel_GSM_Module_Digital_IO_Application_Note
GSM Module Digital IO Application Note
[5]
[6]
[7]
[8]
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[12]
Quectel_GSM_EVB_User_Guide
GSM EVB user guide
[13]
Quectel_Module_Secondary_SMT_User_Guide
Module secondary SMT user guide
Table 37: Terms and Abbreviations
Abbreviation
Description
ADC
Analog-to-Digital Converter
AMR
Adaptive Multi-Rate
ARP
Antenna Reference Point
ASIC
Application Specific Integrated Circuit
BER
Bit Error Rate
BOM
Bill Of Material
BTS
Base Transceiver Station
CHAP
Challenge Handshake Authentication Protocol
CS
Coding Scheme
CSD
Circuit Switched Data
CTS
Clear To Send
DAC
Digital-to-Analog Converter
DRX
Discontinuous Reception
DSP
Digital Signal Processor
DCE
Data Communications Equipment (typically module)
DTE
Data Terminal Equipment (typically computer, external controller)
DTR
Data Terminal Ready
DTX
Discontinuous Transmission
EFR
Enhanced Full Rate
EGSM
Enhanced GSM
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EMC
Electromagnetic Compatibility
ESD
Electrostatic Discharge
ETS
European Telecommunication Standard
FCC
Federal Communications Commission (U.S.)
FDMA
Frequency Division Multiple Access
FR
Full Rate
GMSK
Gaussian Minimum Shift Keying
GPRS
General Packet Radio Service
GSM
Global System for Mobile Communications
G.W
Gross Weight
HR
Half Rate
I/O
Input/Output
IC
Integrated Circuit
IMEI
International Mobile Equipment Identity
Imax
Maximum Load Current
Inorm
Normal Current
kbps
Kilo Bits Per Second
LED
Light Emitting Diode
Li-Ion
Lithium-Ion
MO
Mobile Originated
MOQ
Minimum Order Quantity
MP
Manufacture Product
MS
Mobile Station (GSM engine)
MT
Mobile Terminated
N.W
Net Weight
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PAP
Password Authentication Protocol
PBCCH
Packet Switched Broadcast Control Channel
PCB
Printed Circuit Board
PDU
Protocol Data Unit
PPP
Point-to-Point Protocol
RF
Radio Frequency
RMS
Root Mean Square (value)
RTC
Real Time Clock
RX
Receive Direction
SIM
Subscriber Identification Module
SMS
Short Message Service
TDMA
Time Division Multiple Access
TE
Terminal Equipment
TX
Transmitting Direction
UART
Universal Asynchronous Receiver & Transmitter
URC
Unsolicited Result Code
USSD
Unstructured Supplementary Service Data
VSWR
Voltage Standing Wave Ratio
Vmax
Maximum Voltage Value
Vnorm
Normal Voltage Value
Vmin
Minimum Voltage Value
VIHmax
Maximum Input High Level Voltage Value
VIHmin
Minimum Input High Level Voltage Value
VILmax
Maximum Input Low Level Voltage Value
VILmin
Minimum Input Low Level Voltage Value
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VImax
Absolute Maximum Input Voltage Value
VImin
Absolute Minimum Input Voltage Value
VOHmax
Maximum Output High Level Voltage Value
VOHmin
Minimum Output High Level Voltage Value
VOLmax
Maximum Output Low Level Voltage Value
VOLmin
Minimum Output Low Level Voltage Value
Phonebook Abbreviations
LD
SIM Last Dialing phonebook (list of numbers most recently dialed)
MC
Mobile Equipment list of unanswered MT Calls (missed calls)
ON
SIM (or ME) Own Numbers (MSISDNs) list
RC
Mobile Equipment list of Received Calls
SM
SIM phonebook
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M85 Hardware Design
Appendix B GPRS Coding Scheme
Four coding schemes are used in GPRS protocol. The differences between them are shown in the
following table.
Table 38: Description of Different Coding Schemes
Radio
Block
excl.USF
and BCS
BCS
Tail
Coded
Bits
Punctured
Bits
Data
Rate
Kb/s
40
456
9.05
268
16
588
132
13.4
312
16
676
220
15.6
12
428
16
456
21.4
Scheme
Code
Rate
USF
Pre-coded
USF
CS-1
1/2
181
CS-2
2/3
CS-3
3/4
CS-4
Radio block structure of CS-1, CS-2 and CS-3 is shown as the figure below.
Radio Block
BCS
USF
Rate 1/2 convolutional coding
Puncturing
456 bits
Figure 56: Radio Block Structure of CS-1, CS-2 and CS-3
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Radio block structure of CS-4 is shown as the following figure.
Radio Block
BCS
USF
Block
Code
No coding
456 bits
Figure 57: Radio Block Structure of CS-4
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10
Appendix C GPRS Multi-slot Class
Twenty-nine classes of GPRS multi-slot modes are defined for MS in GPRS specification. Multi-slot
classes are product dependant, and determine the maximum achievable data rates in both the uplink and
downlink directions. Written as 3+1 or 2+2, the first number indicates the amount of downlink timeslots,
while the second number indicates the amount of uplink timeslots. The active slots determine the total
number of slots the GPRS device can use simultaneously for both uplink and downlink communications.
The description of different multi-slot classes is shown in the following table.
Table 39: GPRS Multi-slot Classes
Multislot Class
Downlink Slots
Uplink Slots
Active Slots
10
11
12
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