Simcom 1005242010007 SIM900B Wireless Module User Manual

Shanghai Simcom Ltd. SIM900B Wireless Module

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Hardware Design
SIM900B_HD_V1.03
SIM900B Hardware Design
Document Title:
SIM900B Hardware Design
Version:
1.03
Date:
2010-06-24
Status:
Release
Document Control ID:
SIM900B_HD_V1.03
General Notes
SIMCom offers this information as a service to its customers, to support application and engineering efforts
that use the products designed by SIMCom. The information provided is based upon requirements
specifically provided to SIMCom by the customers. SIMCom has not undertaken any independent search for
additional relevant information, including any information that may be in the customer’s possession.
Furthermore, system validation of this product designed by SIMCom within a larger electronic system
remains the responsibility of the customer or the customer’s system integrator. All specifications supplied
herein are subject to change.
Copyright
This document contains proprietary technical information which is the property of SIMCom Limited,
copying of this document and giving it to others and the using or communication of the contents thereof, are
forbidden without express authority. Offenders are liable to the payment of damages. All rights reserved in
the event of grant of a patent or the registration of a utility model or design. All specification supplied herein
are subject to change without notice at any time.
Copyright © Shanghai SIMCom Wireless Solutions Ltd. 2010
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SIM900B Hardware Design
Contents
Contents .....................................................................................................................................................................3
Version history...........................................................................................................................................................7
1 Introduction.............................................................................................................................................................8
1.1 Related Documents .......................................................................................................................................8
1.2 Terms and Abbreviations...............................................................................................................................8
1.3 Safety Caution............................................................................................................................................. 11
2 SIM900B Overview ..............................................................................................................................................13
2.1 SIM900B Key Features...............................................................................................................................13
2.2 SIM900B Functional Diagram ....................................................................................................................15
2.3 SIM900B Evaluation Board ........................................................................................................................16
3 Application Interface.............................................................................................................................................18
3.1 SIM900B Pin Description ...........................................................................................................................18
3.2 Operating Modes .........................................................................................................................................21
3.3 Power Supply ..............................................................................................................................................22
3.3.1 Power Supply Pins.............................................................................................................................23
3.3.2 Minimizing Power Losses .................................................................................................................24
3.3.3 Monitoring Power Supply .................................................................................................................24
3.4 Power Up and Power Down Scenarios........................................................................................................24
3.4.1 Turn on SIM900B..............................................................................................................................24
3.4.2 Turn Off SIM900B ............................................................................................................................26
3.4.3 Restart SIM900B Using the PWRKEY Pin.......................................................................................28
3.5 Power Saving ..............................................................................................................................................28
3.5.1 Minimum Functionality Mode ..........................................................................................................28
3.5.2 Sleep Mode (Slow Clock Mode) .......................................................................................................29
3.5.3 Wake Up SIM900B from SLEEP Mode ...........................................................................................29
3.6 Summary of State Transitions (except SLEEP mode).................................................................................29
3.7 RTC Backup ................................................................................................................................................30
3.8 Serial Interfaces...........................................................................................................................................31
3.8.1 Function of serial port & debug port supporting ...............................................................................33
3.8.2 Software Upgrade and Software Debug ............................................................................................34
3.9 Audio Interfaces ..........................................................................................................................................35
3.9.1 Speaker Interface Configuration........................................................................................................36
3.9.2 Microphone Interfaces Configuration ...............................................................................................37
3.9.3 Earphone Interface Configuration .....................................................................................................37
3.9.4 Referenced Electronic Characteristic ................................................................................................38
3.10 Buzzer .......................................................................................................................................................39
3.11 SIM Card Interface....................................................................................................................................40
3.11.1 SIM Card Application .....................................................................................................................40
3.11.2 Design Considerations for SIM Card Holder ..................................................................................41
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3.12 LCD Display Interface ..............................................................................................................................44
3.13 Keypad Interface .......................................................................................................................................44
3.14 ADC ..........................................................................................................................................................45
3.15 Behaviors of the RI ...................................................................................................................................46
3.16 Network Status Indication .........................................................................................................................46
3.17 General Purpose Input Output (GPIO) ......................................................................................................48
4 Antenna Interface ..................................................................................................................................................49
4.1 Module RF Output Power ...........................................................................................................................50
4.2 Module RF Receive Sensitivity...................................................................................................................50
4.3 Module Operating Frequencies ...................................................................................................................50
5 Electrical, Reliability and Radio Characteristics...................................................................................................50
5.1 Absolute Maximum Ratings........................................................................................................................50
5.2 Operating Temperatures..............................................................................................................................51
5.3 Power Supply Ratings .................................................................................................................................51
5.4 Current Consumption ..................................................................................................................................52
5.5 Electro-Static Discharge..............................................................................................................................53
6 Mechanics .............................................................................................................................................................55
6.1 Mechanical Dimensions of SIM900B .........................................................................................................55
6.2 Top View of the SIM900B ..........................................................................................................................56
6.3 Mounting SIM900B onto the application platform .....................................................................................57
6.4 Board-to-board connector ...........................................................................................................................57
6.4.1 Mechanical dimensions of the SUNCAGEY BB530-06001-20R .....................................................57
6.5 RF connector ...............................................................................................................................................59
6.6 PIN Assignment of SIM900B .....................................................................................................................61
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Table Index
TABLE 1: RELATED DOCUMENTS ............................................................................................................................... 8
TABLE 2: TERMS AND ABBREVIATIONS ................................................................................................................... 8
TABLE 3: SIM900B KEY FEATURES ........................................................................................................................... 13
TABLE 4: CODING SCHEMES AND MAXIMUM NET DATA RATES OVER AIR INTERFACE ............................ 15
TABLE 5: PIN DESCRIPTION ....................................................................................................................................... 18
TABLE 6: OVERVIEW OF OPERATING MODES........................................................................................................ 21
TABLE 7: PIN DEFINITION OF THE SERIAL INTERFACES .................................................................................... 31
TABLE 8: LOGIC LEVELS OF THE SERIAL PORT AND DEBUG PORT ................................................................. 32
TABLE 9: PIN DEFINE OF THE AUDIO INTERFACE ................................................................................................ 35
TABLE 10: MIC INPUT CHARACTERISTICS ............................................................................................................. 38
TABLE 11: AUDIO OUTPUT CHARACTERISTICS .................................................................................................... 38
TABLE 12: BUZZER OUTPUT CHARACTERISTICS ................................................................................................. 39
TABLE 13: PIN DEFINE OF THE SIM INTERFACE.................................................................................................... 40
TABLE 14: PIN DESCRIPTION (AMPHENOL SIM CARD HOLDER) ...................................................................... 42
TABLE 15: PIN DESCRIPTION (MOLEX SIM CARD HOLDER) .............................................................................. 43
TABLE 16: PIN DEFINE OF THE LCD INTERFACE................................................................................................... 44
TABLE 17: PIN DEFINE OF THE KEYPAD INTERFACE........................................................................................... 44
TABLE 18: ADC SPECIFICATION ................................................................................................................................ 45
TABLE 19: BEHAVIOURS OF THE RI.......................................................................................................................... 46
TABLE 20: WORKING STATE OF THE NETLIGHT ................................................................................................... 47
TABLE 21: PIN DEFINE OF THE GPIO INTERFACE ................................................................................................. 48
TABLE 22: SIM900B CONDUCTED RF OUTPUT POWER ........................................................................................ 50
TABLE 23: SIM900B CONDUCTED RF RECEIVE SENSITIVITY ............................................................................ 50
TABLE 24: SIM900B OPERATING FREQUENCIES.................................................................................................... 50
TABLE 25: ABSOLUTE MAXIMUM RATINGS........................................................................................................... 51
TABLE 26: SIM900B OPERATING TEMPERATURE .................................................................................................. 51
TABLE 27: SIM900B POWER SUPPLY RATINGS....................................................................................................... 51
TABLE 28: SIM900B CURRENT CONSUMPTION（VBAT=3.8V） ......................................................................... 52
TABLE 29: THE ESD ENDURE STATUE MEASURED TABLE (TEMPERATURE: 25℃, HUMIDITY:45% ) ........ 53
TABLE 30: PIN ASSIGNMENT...................................................................................................................................... 61
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Figure Index
FIGURE 1: SIM900B FUNCTIONAL DIAGRAM......................................................................................................... 16
FIGURE 2: TOP VIEW OF SIM900B EVB .................................................................................................................... 17
FIGURE 3: REFERENCE CIRCUIT OF THE VBAT INPUT ........................................................................................ 22
FIGURE 4: REFERENCE CIRCUIT OF THE SOURCE POWER SUPPLY INPUT..................................................... 23
FIGURE 5: VBAT VOLTAGE DROP DURING TRANSMIT BURST........................................................................... 23
FIGURE 6: TURN ON SIM900B USING DRIVING CIRCUIT..................................................................................... 25
FIGURE 7: TURN ON SIM900B USING BUTTON ...................................................................................................... 25
FIGURE 8: TIMING OF TURN ON SYSTEM USING PWRKEY ................................................................................ 26
FIGURE 9: TIMING OF TURN OFF SYSTEM USING PWRKEY............................................................................... 26
FIGURE 10: TIMING OF RESTART SYSTEM ............................................................................................................. 28
FIGURE 11: STATE TRANSITION ................................................................................................................................ 29
FIGURE 12: RTC SUPPLY FROM NON-CHARGEABLE BATTERY ......................................................................... 30
FIGURE 13: RTC SUPPLY FROM RECHARGEABLE BATTERY .............................................................................. 30
FIGURE 14: RTC SUPPLY FROM CAPACITOR .......................................................................................................... 31
FIGURE 15: SEIKO XH414H-IV01E CHARGE CHARACTERISTIC ......................................................................... 31
FIGURE 16: CONNECTION OF THE SERIAL INTERFACES..................................................................................... 33
FIGURE 17: CONNECTION OF SOFTWARE UPGRADE AND SOFTWARE DEBUG ............................................. 34
FIGURE 18: RS232 LEVEL CONVERTER CIRCUIT................................................................................................... 35
FIGURE 19: SPEAKER INTERFACE CONFIGURATION ........................................................................................... 36
FIGURE 20: SPEAKER INTERFACE WITH AMPLIFIER CONFIGURATION .......................................................... 36
FIGURE 21: MICROPHONE INTERFACE CONFIGURATION................................................................................... 37
FIGURE 22: EARPHONE INTERFACE CONFIGURATION........................................................................................ 37
FIGURE 23: REFERENCE CIRCUIT OF BUZZER ...................................................................................................... 39
FIGURE 24: REFERENCE CIRCUIT OF THE 8 PINS SIM CARD.............................................................................. 41
FIGURE 25: REFERENCE CIRCUIT OF THE 6 PINS SIM CARD.............................................................................. 41
FIGURE 26: AMPHENOL C707 10M006 512 2 SIM CARD HOLDER........................................................................ 42
FIGURE 27: MOLEX 91228 SIM CARD HOLDER ...................................................................................................... 43
FIGURE 28: REFERENCE CIRCUIT OF THE KEYPAD INTERFACE ....................................................................... 45
FIGURE 29: SIM900B SERVICES AS RECEIVER ....................................................................................................... 46
FIGURE 30: SIM900B SERVICES AS CALLER ........................................................................................................... 46
FIGURE 31: REFERENCE CIRCUIT OF NETLIGHT .................................................................................................. 47
FIGURE 32 : THE RF INTERFACE OF MODULE ....................................................................................................... 49
FIGURE 33: TOP AN SIDE MECHANICAL DIMENSIONS OF MODULE （UNIT: MM）.................................... 55
FIGURE 34：MECHANICAL DIMENSIONS OF MODULE PCB DECAL（UNIT: MM）...................................... 56
FIGURE 35: TOP VIEW OF THE SIM900B................................................................................................................... 56
FIGURE 36: SUNCAGEY BB530-06001-20R BOARD-TO-BOARD CONNECTOR.................................................. 57
FIGURE 37 BOARD-TO-BOARD CONNECTOR PHYSICAL PHOTO ...................................................................... 58
FIGURE 38: U.FL-R-SMT............................................................................................................................................... 59
FIGURE 39: U.FL SERIES RF ADAPTER CABLE ....................................................................................................... 60
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Version history
Date
Version
Description of change
Author
2010-04-08
1.01
Origin
Huangqiuju
2010-05-31
1.02
Modify voltage domain ， current consumption and
figure37
Huangqiuju
2010-06-23
1.03
§2.1, §3.3. §3.4 Modify the power supply range from
3.2V~4.8V to 3.1V~4.8V
§3.7, Modify the VRTC pin connection when RTC
backup is not needed.
Huangqiuju
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1 Introduction
This document describes the hardware interface of the SIMCom SIM900B module that connects to the specific
application and the air interface. As SIM900B can be integrated with a wide range of applications, all functional
components of SIM900B are described in great detail.
This document can help you quickly understand SIM900B interface specifications, electrical and mechanical
details. With the help of this document and other SIM900B application notes, user guide, the user can use
SIM900B module to design and set-up mobile applications quickly.
1.1 Related Documents
Table 1: Related documents
SN
Document name
Remark
[1]
SIM900_ATC
SIM900_ATC
[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
[5]
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)
[6]
GSM 11.14:
Digital cellular telecommunications system (Phase 2+); Specification of the SIM
Application Toolkit for the Subscriber Identity Module – Mobile Equipment
(SIM – ME) interface
[7]
GSM 11.11:
Digital cellular telecommunications system (Phase 2+); Specification of the
Subscriber Identity Module – Mobile Equipment (SIM – ME) interface
[8]
GSM 03.38:
Digital cellular telecommunications system (Phase 2+); Alphabets and
language-specific information
[9]
GSM 11.10
Digital cellular telecommunications system (Phase 2)； Mobile Station (MS)
conformance specification； Part 1: Conformance specification
[10]
AN_Serial Port
AN_Serial Port
1.2 Terms and Abbreviations
Table 2: Terms and Abbreviations
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Abbreviation
Description
ADC
Analog-to-Digital Converter
AMR
Adaptive Multi-Rate
ARP
Antenna Reference Point
ASIC
Application Specific Integrated Circuit
BER
Bit Error Rate
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
DTE
Data Terminal Equipment (typically computer, terminal, printer)
DTR
Data Terminal Ready
DTX
Discontinuous Transmission
EFR
Enhanced Full Rate
EGSM
Enhanced GSM
EMC
Electromagnetic Compatibility
ESD
Electrostatic Discharge
ETS
European Telecommunication Standard
FCC
Federal Communications Commission (U.S.)
FDMA
Frequency Division Multiple Access
FR
Full Rate
GMSK
Gaussian Minimum Shift Keying
GPRS
General Packet Radio Service
GSM
Global Standard for Mobile Communications
HR
Half Rate
I/O
Input/Output
IC
Integrated Circuit
IMEI
International Mobile Equipment Identity
kbps
Kilo bits per second
LED
Light Emitting Diode
Li-Ion
Lithium-Ion
MO
Mobile Originated
MS
Mobile Station (GSM engine), also referred to as TE
MT
Mobile Terminated
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Abbreviation
Description
PAP
Password Authentication Protocol
PBCCH
Packet Switched Broadcast Control Channel
PCB
Printed Circuit Board
PCS
Personal Communication System, also referred to as GSM 1900
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, also referred to as DTE
TX
Transmit Direction
UART
Universal Asynchronous Receiver & Transmitter
URC
Unsolicited Result Code
USSD
Unstructured Supplementary Service Data
VSWR
Voltage Standing Wave Ratio
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
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
Inorm
Normal Current
Imax
Maximum Load Current
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Phonebook abbreviations
Abbreviation
Description
FD
SIM fix dialing phonebook
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
NC
Not connect
1.3 Safety Caution
The following safety precautions must be observed during all phases of the operation. Usage, service or repair of
any cellular terminal or mobile incorporating SIM900B module. Manufactures of the cellular terminal should send
words the following safety information to users and operating personnel and to incorporate these guidelines into
all manuals supplied with the product. If not so, SIMCom does not take on any liability for customer failure to
comply with these precautions.
When in a hospital or other health care facility, observe the restrictions about the
use of mobiles. Switch the cellular terminal or mobile off, medical equipment may be sensitive
to not operate normally for RF energy interference.
Switch off the cellular terminal or mobile before boarding an aircraft. Make sure it be switched
off. The operation of wireless appliances in an aircraft is forbidden to prevent interference with
communication systems. Forget to think much of these instructions may lead to the flight safety
or offend against local legal action, or both.
Do not operate the cellular terminal or mobile in the presence of flammable gases or fumes.
Switch off the cellular terminal when you are near petrol stations, fuel depots, chemical plants or
where blasting operations are in progress. Operation of any electrical equipment in potentially
explosive atmospheres can constitute a safety hazard.
Your cellular terminal or mobile receives and transmits radio frequency energy while switched
on. RF interference can occur if it is used close to TV sets, radios, computers or other electric
equipment.
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Road safety comes first! Do not use a hand-held cellular terminal or mobile when driving a
vehicle, unless it is securely mounted in a holder for hands free operation. Before making a
call with a hand-held terminal or mobile, park the vehicle.
GSM cellular terminals or mobiles operate over radio frequency signals and cellular networks
and cannot be guaranteed to connect in all conditions, for example no mobile fee or a invalid
SIM card. While you are in this condition and need emergent help, Please Remember using
emergency calls. In order to make or receive calls, the cellular terminal or mobile must be
switched on and in a service area with adequate cellular signal strength.
Some networks do not allow for emergency call if certain network services or phone features are
in use (e.g. lock functions, fixed dialing etc.). You may
have to deactivate those features before you can make an emergency call.
Also, some networks require that a valid SIM card be properly inserted in the cellular terminal
or mobile.
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2 SIM900B Overview
Designed for global market, SIM900B is a quad-band GSM/GPRS engine that works on frequencies GSM
850MHz, EGSM 900MHz, DCS 1800MHz and PCS 1900MHz. SIM900B features GPRS multi-slot class 10/
class 8 (optional) and supports the GPRS coding schemes CS-1, CS-2, CS-3 and CS-4.
With a tiny configuration of 40mm x 33mm x 3mm, SIM900B can meet almost all the space requirements in your
applications, such as M2M, smart phone, PDA and other mobile devices.
The physical interface to the mobile application is a 60-pin board-to-board connector, which provides all
hardware interfaces between the module and customers’ boards except the RF antenna interface.
The keypad and SPI display interface will give you the flexibility to develop customized applications.
Serial port and Debug port can help you easily develop your applications.
Two audio channels include a microphone input and a speaker output.
Programmable general purpose input & output.
The SIM900B is designed with power saving technique so that the current consumption is as low as 1.2mA in
SLEEP mode.
The SIM900B is integrated with the TCP/IP protocol; extended TCP/IP AT commands are developed for
customers to use the TCP/IP protocol easily, which is very useful for those data transfer applications.
2.1 SIM900B Key Features
Table 3: SIM900B key features
Feature
Implementation
Power supply
Single supply voltage :3.1V – 4.8V
Power saving
Typical power consumption in SLEEP mode is 1.2mA ( BS-PA-MFRMS=5)
Frequency Bands
Quad-band: GSM 850, EGSM 900, DCS 1800, PCS 1900. The SIM900B can
search the 4 frequency bands automatically. The frequency bands also can be
set by AT command.
Compliant to GSM Phase 2/2+
GSM class
Small MS
Transmitting power
Class 4 (2W) at GSM 850 and EGSM 900
Class 1 (1W) at DCS 1800 and PCS 1900
GPRS connectivity
GPRS multi-slot class 10 （default）
GPRS multi-slot class 8 (option)
GPRS mobile station class B
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Temperature range
Normal operation: -30°C to +80°C
Restricted operation: -40°C to -30°C and +80 °C to +85°C(1)
Storage temperature -45°C to +90°C
DATA GPRS:
GPRS data downlink transfer: max. 85.6 kbps
GPRS data uplink transfer: max. 42.8 kbps
Coding scheme: CS-1, CS-2, CS-3 and CS-4
Supports the protocols PAP (Password Authentication Protocol) usually used
for PPP connections.
Integrates the TCP/IP protocol.
Support Packet Switched Broadcast Control Channel (PBCCH)
CSD transmission rates: 2.4, 4.8, 9.6, 14.4 kbps, non-transparent
Unstructured Supplementary Services Data (USSD) support
SMS
MT, MO, CB, Text and PDU mode
SMS storage: SIM card
FAX
Group 3 Class 1
SIM interface
Support SIM card: 1.8V, 3V
External antenna
Connected via 50 Ohm antenna connector or antenna pad
Audio features
Speech codec modes:
z Half Rate (ETS 06.20)
z Full Rate (ETS 06.10)
z Enhanced Full Rate (ETS 06.50 / 06.60 / 06.80)
z Adaptive multi rate (AMR)
z Echo Cancellation
z Noise Suppression
CSD:
Serial port and
Debug port
Serial Port:
7-wire modem interface with status and control lines, unbalanced,
asynchronous.
1200bps to 115200bps.
Serial Port can be used for AT commands or data stream.
Supports RTS/CTS hardware handshake and software ON/OFF flow control.
Multiplex ability according to GSM 07.10 Multiplexer Protocol.
Autobauding supports baud rate from 1200 bps to 57600bps.
Debug port:
2-wire interface DBG_TXD and DBG_RXD.
Can be used for debugging and firmware upgrade.
Phonebook management
Support phonebook types: SM, FD, LD, RC, ON, MC.
SIM Application Toolkit
Support SAT class 3, GSM 11.14 Release 99
Real time clock
Implemented
Timer function
Programmable via AT command
Physical characteristics
Size: 40mm x 33mm x 3.0mm
Weight: 7g
Firmware upgrade
Firmware upgrade over debug port.
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(1) The SIM900B does work, but deviations from the GSM specification may occur.
Table 4: 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
2.2 SIM900B Functional Diagram
The following figure shows a functional diagram of the SIM900B and illustrates the mainly functional part:
z The GSM baseband engine
z Flash and SRAM
z The GSM radio frequency part
z The antenna interface
z The board-to-board interface
z The Other interfaces
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A ntenna
connector
S IM 900B
Radio
Frequency
POWER
KEYPADS
Flash+
SRAM
Baseband
Engine
LCD
UART
GPIO
ADC
AUDIO
Board-to-board Connector
SIM
Figure 1: SIM900B functional diagram
2.3 SIM900B Evaluation Board
In order to help you on the application of SIM900B, SIMCom can supply an Evaluation Board (EVB) that
interfaces the SIM900B directly with appropriate power supply, SIM card holder, RS232 serial port, handset port,
earphone port, antenna and all GPIO of the SIM900B.
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Figure 2: Top view of SIM900B EVB
For details please refer to the SIM900B-EVB_UGD document.
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3 Application Interface
SIM900B is equipped with a 60-pin 0.5mm pitch board-to-board connector that connects to the cellular
application platform. Sub-interfaces included in this board-to-board connector are described in detail in following
chapters:
z Power supply (please refer to Chapter 3.3)
z Serial interfaces (please refer to Chapter 3.8)
z Analog audio interfaces (please refer to Chapter 3.9)
z SIM interface (please refer to Chapter 3.11)
Electrical and mechanical characteristics of the board-to-board connector are specified in Chapter 6. There we also
include order information for mating connectors.
3.1 SIM900B Pin Description
Table 5: Pin description
Power Supply
PIN NAME
I/O
DESCRIPTION
DC CHARACTERISTICS
8 VBAT pins are dedicated to
connect the supply voltage.
The power supply of SIM900B
has to be a single voltage
source of VBAT= 3.2V...4.8V.
It must be able to provide
sufficient current in a transmit
burst which typically rises to
2A
Vmax= 4.8V
Vmin=3.1V
Vnorm=4.0V
COMMENT
VBAT
VRTC
I/O
Current input for RTC when
the battery is not supplied for
the system.
Current output for backup
battery when the main battery
is present and the backup
battery is in low voltage state.
Vmax=3.15V
Vmin=2.0V
Vnorm=3.0V
Iout(max)= 200uA
Iin=3 uA
If the RTC function
is
enabled,
backup battery or
capacitor should be
connected to the
VRTC
pin.
Otherwise connect
a 4.7uF capacitor
to the VRTC pin.
VDD_EXT
2.8V output power supply
Vmax=2.95V
Vmin=2.70V
Vnorm=2.80V
If unused,
open.
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Iout(max)= 10mA
GND
Ground
Power on or power off
PIN NAME
I/O
DESCRIPTION
DC CHARACTERISTICS
PWRKEY
Power on/off detect, active low.
VILmax=0.9V
VIHmin=2.6V
VImax=3.3V
VILmin= 0V
It is already pulled
up internally (3V).
PIN NAME
I/O
DESCRIPTION
DC CHARACTERISTICS
COMMENT
MIC1P
MIC1N
Positive
and
voice-band input
Audio DC Characteristics
refer to chapter 3.9.4
If unused
open
keep
MIC2P
MIC2N
Auxiliary positive and negative
voice-band input
SPK1P
SPK1N
Positive
and
voice-band output
If unused
open
keep
SPK2P
SPK2N
Auxiliary positive and negative
voice-band output
Audio interfaces
AGND
negative
negative
Analog ground
Separate
ground
connection
for
external
audio
circuits.
If unused keep
open.
Display interface
PIN NAME
I/O
DESCRIPTION
DC CHARACTERISTICS
COMMENT
DISP_RST
Display interface
I/O
If unused
open
keep
DISP_DATA
DISP _CLK
DISP _CS
DISP _D/C
VILmax=0.15 *VDD_EXT
VIHmin=0.85*VDD_EXT
VILmin= 0V
VIHmax= VDD_EXT
VOHmin= VDD_EXT-0.1V
VOLmax=0.1V
VOHmax= VDD_EXT
VOLmin= 0V
VILmax=0.15 *VDD_EXT
VIHmin=0.85*VDD_EXT
If unused
open
keep
General purpose input/output
GPIO1/ KBC4
SIM900B_HD_V1.03
I/O
Default as GPIO,can
multiplexed as keypad
be
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GPIO2/ KBC3
I/O
GPIO3/ KBC2
I/O
GPIO4/ KBC1
I/O
GPIO6/ KBR3
I/O
GPIO7/ KBR4
I/O
GPIO8/ KBR2
I/O
GPIO9/ KBR1
I/O
KBR0
KBC0
VILmin= 0V
VIHmax= VDD_EXT
VOHmin= VDD_EXT-0.1V
VOLmax=0.1V
VOHmax= VDD_EXT
VOLmin= 0V
Just for power
down, If unused
keep open
Serial port
PIN NAME
I/O
DESCRIPTION
DC CHARACTERISTICS
COMMENT
RXD
Receive data
TXD
Transmit data
RTS
Request to send
CTS
Clear to send
RI
Ring indicator
DCD
Data carry detect
DTR Pin has
been pulled up to
VDD_EXT
internally.
If
unused
keep
open
DTR
Data terminal Ready
VILmax=0.15 *VDD_EXT
VIHmin=0.85*VDD_EXT
VILmin= 0V
VIHmax= VDD_EXT
VOHmin= VDD_EXT-0.1V
VOLmax=0.1V
VOHmax= VDD_EXT
VOLmin= 0V
PIN NAME
I/O
DESCRIPTION
DC CHARACTERISTICS
COMMENT
DBG_TXD
Serial interface for debugging
and firmware upgrade
If unused
open
DBG_RXD
VILmax=0.15 *VDD_EXT
VIHmin=0.85*VDD_EXT
VILmin= 0V
VIHmax= VDD_EXT
VOHmin= VDD_EXT-0.1V
VOLmax=0.1V
VOHmax= VDD_EXT
VOLmin= 0V
COMMENT
Debug interface
SIM interface
PIN NAME
I/O
DESCRIPTION
DC CHARACTERISTICS
SIM_VDD
Voltage supply for SIM card
The voltage can be select by
software automatically
either 1.8V or 3V
SIM_DATA
I/O
SIM data output
VILmax=0.15 *SIM_VDD
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SIM_CLK
SIM clock
VIHmin=0.85*SIM_VDD
VILmin= 0V
VIHmax= SIM_VDD
VOHmin= SIM_VDD-0.1V
VOLmax=0.1V
VOHmax= SIM_VDD
VOLmin= 0V
SIM_RST
SIM reset
SIM_PRESENCE
SIM detect
VILmax=0.15 *VDD_EXT
VIHmin=0.85*VDD_EXT
VILmin= 0V
VIHmax= VDD_EXT
If unused
open
PIN NAME
I/O
DESCRIPTION
DC CHARACTERISTICS
COMMENT
ADC0
General purpose analog to
digital converter.
Input voltage range: 0V ~
2.8V
If unused
open
keep
ADC
keep
Pulse Width Modulation
PIN NAME
I/O
DESCRIPTION
DC CHARACTERISTICS
COMMENT
BUZZER
PWM Output
VOHmin= VDD_EXT-0.1V
VOLmax=0.1V
VOHmax= VDD_EXT
VOLmin=0
If unused
open
keep
3.2 Operating Modes
The table below briefly summarizes the various operating modes referred to in the following chapters.
Table 6: Overview of operating modes
Mode
Function
Normal
operation
GSM/GPRS
SLEEP
Module will automatically go into SLEEP mode if DTR is set to high level
and there is no on air and no hardware interrupt (such as GPIO interrupt or
data on serial port).
In this case, the current consumption of module will reduce to the minimal
level.
In SLEEP mode, the module can still receive paging message and SMS
from the BTS normally.
GSM IDLE
Software is active. Module has registered to the GSM network, and the
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module is ready to send and receive.
GSM TALK
Connection between two subscribers is in progress. In this case, the power
consumption depends on network settings such as DTX off/on,
FR/EFR/HR, hopping sequences, antenna.
GPRS
STANDBY
Module is ready for GPRS data transfer, but no data is currently sent or
received. In this case, power consumption depends on network settings and
GPRS configuration.
GPRS DATA
There is GPRS data transfer (PPP or TCP or UDP) in progress. In this case,
power consumption is related with network settings (e.g. power control
level), uplink / downlink data rates and GPRS configuration (e.g. used
multi-slot settings).
POWER
DOWN
Normal shutdown by sending the “AT+CPOWD=1” command or using the PWRKEY. The
power management ASIC disconnects the power supply from the baseband part of the
module, and only the power supply for the RTC is remained. Software is not active. The
serial port is not accessible. Operating voltage (connected to VBAT) remains applied.
Minimum
functionality
mode (without
remove power
supply)
Use the “AT+CFUN” command can set the module to a minimum functionality mode
without remove 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 closed, and the serial
port is still accessible. The power consumption in this case is very low.
3.3 Power Supply
The power supply of SIM900B is from a single voltage source of VBAT= 3.1V...4.8V. In some case, the ripple in
a transmitting burst may cause voltage drops when current consumption rises to typical peaks of 2A. So the power
supply must be able to provide sufficient current up to 2A.
For the VBAT input, a local bypass capacitor is recommended. A capacitor (about 100 µF, low ESR) is
recommended. Multi-layer ceramic chip (MLCC) capacitors can provide the best combination of low ESR and
small size but may not be cost effective. A lower cost choice may be a 100 µF tantalum capacitor (low ESR) with
a small (0.1µF to 1µF) ceramic in parallel, which is illustrated as following figure. The capacitors should be
placed as close as possible to the SIM900B VBAT pins. The following figure is the recommended circuit.
VBAT
CA
CB
Figure 3: Reference circuit of the VBAT input
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The circuit design of the power supply depends strongly upon the power source where this power is drained. The
following figure is the reference design of +5V input source power supply. The designed output for the power
supply is 4.1V, thus a linear regulator can be used. If there’s a big difference between the input source and the
desired output (VBAT), a switching converter power supply will be preferable because of its better efficiency
especially with the 2A peak current in burst mode of the module.
A single 3.6V Li-Ion cell battery type can be connected to the power supply of the SIM900B VBAT directly. But
the Ni_Cd or Ni_MH battery types must be used carefully, since their maximum voltage can rise over the absolute
maximum voltage of the module and damage it.
Figure 4: Reference circuit of the source power supply input
The following figure is the VBAT voltage ripple wave at the maximum power transmit phase, the test condition is
VBAT=4.0V, VBAT maximum output current =2A, CA=100µF tantalum capacitor (ESR=0.7Ω) and CB=1µF.
577us
4.615ms
IVBAT
Burst:2A
VBAT
Max:300mV
Figure 5: VBAT voltage drop during transmit burst
3.3.1 Power Supply Pins
Eight VBAT pins of the board-to-board connector are dedicated to connect the supply voltage; six GND pins are
recommended for grounding. VRTC pin can be used to back up the RTC.
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3.3.2 Minimizing Power Losses
When designing the power supply for your application please pay specific attention to power losses. Ensure that
the input voltage VBAT never drops below 3.2V even in a transmit burst where current consumption can rise to
typical peaks of 2A. If the power voltage drops below 3.2V, the module may be switched off. The PCB traces
from the VBAT pins to the power source must be wide enough to decrease voltage drops in the transmitting burst
mode.
3.3.3 Monitoring Power Supply
To monitor the supply voltage, the user can use the “AT+CBC” command which include a parameter: voltage
value (in mV).
The voltage is continuously measured at intervals depending on the operating mode. The displayed voltage (in
mV) is averaged over the last measuring period before the “AT+CBC” command is executed.
For details please refer to document [1]
3.4 Power Up and Power Down Scenarios
In general, be sure not to turn on SIM900B while it is beyond the safety limits of voltage and temperature stated
in Chapter 3.4.2. SIM900B would immediately switch off after having started and detected these inappropriate
conditions. In extreme cases this can cause permanent damage to the module.
3.4.1 Turn on SIM900B
SIM900B can be turned on by the following way, which is described in following chapters:
Via PWRKEY pin: starts normal operating mode (please refer to chapter 3.4.1.1);
Note: The AT command must be set after the SIM900B is power on and Unsolicited Result Code “RDY” is
received from the serial port. However if the SIM900B is set autobauding, the serial port will receive nothing.
The AT commands can be set after the SIM900B is power on. “AT+IPR=x” can be used to set a fixed baud
rate and save the configuration to non-volatile flash memory. After the configuration is saved as fixed baud
rate, the Code “RDY” should be received from the serial port all the time that the SIM900B is power on.
Please refer to the chapter “AT+IPR” in document [1].
3.4.1.1 Turn on SIM900B Using the PWRKEY Pin (Power on)
The SIM900B can be turn on by driving the PWRKEY to a low level voltage for some time and then release.
This pin has pulled up to a 3V voltage source in the module. The simple circuit illustrates as the following
figures.
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3V
100K
1K
POWERKEY
4.7k
Turn on impulse
Module
47k
Figure 6: Turn on SIM900B using driving circuit
S1
PWRKEY
TVS1
Figure 7: Turn on SIM900B using button
The power on scenarios illustrates as following figure.
Pulldown >1s
Delay > 2.2s
VBAT
V IH > 2.55V
PWRKEY
(INPUT)
Serial Port
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Undefined
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Figure 8: Timing of turn on system using PWRKEY
When power on procedure completes, the SIM900B will send out following result code to indicate the module is
ready to operate when set as fixed baud rate.
RDY
This result code does not appear when autobauding is active.
3.4.2 Turn Off SIM900B
Following ways can be used to turn off the SIM900B:
z Normal power down procedure: Turn off SIM900B using the PWRKEY pin
z Normal power down procedure: Turn off SIM900B using AT command
z Over-voltage or under-voltage automatic shutdown: Take effect if over-voltage or under-voltage is detected
z Over-temperature or under-temperature automatic shutdown: Take effect if over-temperature or
under-temperature is detected
3.4.2.1 Turn Off SIM900B Using the PWRKEY Pin (Power down)
The SIM900B can be turned off by driving the PWRKEY to a low level voltage for a short time and then release.
Please refer to the turn on circuit. The power down scenario illustrates as following figure.
This procedure lets the module log off from the network and allows the software to enter into a secure state and
save data before completely disconnecting the power supply.
Before the completion of the switching off procedure the module will send out result code:
NORMAL POWER DOWN
After this moment, the AT commands can’t be executed. The module enters the POWER DOWN mode, only the
RTC is still active. POWER DOWN can also be indicated by VDD_EXT pin, which is a low level voltage in this
mode.
Pulldown >1s
Delay > 1.7s
PWRKEY
(INPUT)
Logout net
VIH > 2.55V
VIL<0.9V
VDD_EXT
（OUTPUT）
VOL < 0.1V
Figure 9: Timing of turn off system using PWRKEY
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3.4.2.2 Turn Off SIM900B Using AT Command
AT command “AT+CPOWD=1”can be use to turn off the module. This command lets the module log off from
the network and allows the module to enter into a secure state and save data before completely disconnecting the
power supply.
Before the completion of the switching off procedure the module will send out result code:
NORMAL POWER DOWN
After this moment, the AT commands can’t be executed. The module enters the POWER DOWN mode, only the
RTC is still active. POWER DOWN can also be indicated by VDD_EXT pin, which is a low level voltage in this
mode.
Please refer to document [1] for detail about the AT command of “AT+CPOWD”.
3.4.2.3 Over-voltage or Under-voltage Automatic Shutdown
The module will constantly monitor the voltage applied on the VBAT. If the voltage ≤ 3.2V, the following URC
will be presented:
UNDER-VOLTAGE WARNNING
If the voltage ≥ 4.7V, the following URC will be presented:
OVER-VOLTAGE WARNNING
The uncritical voltage range is 3.1V to 4.8V. If the voltage > 4.8V or < 3.1V, the module will be automatic
shutdown soon.
If the voltage < 3.1V, the following URC will be presented:
UNDER-VOLTAGE POWER DOWN
If the voltage > 4.8V, the following URC will be presented:
OVER-VOLTAGE POWER DOWN
After this moment, no further more AT commands can be executed. The module logs off from network and enters
POWER DOWN mode, and only the RTC is still active. POWER DOWN can also be indicated by VDD_EXT
pin, which is a low level voltage in this mode.
3.4.2.4 Over-temperature or Under-temperature Automatic Shutdown
The module will constantly monitor the temperature of the module, if the temperature > +80℃, the following
URC will be presented:
+CMTE:1
If the temperature < -30℃, the following URC will be presented:
+CMTE:-1
The uncritical temperature range is -40℃ to +85℃. If the temperature > +85℃ or < -40℃, the module will be
automatic shutdown soon.
If the temperature >+ 85℃, the following URC will be presented:
+CMTE:2
If the temperature < -40℃, the following URC will be presented:
+CMTE:-2
After this moment, the AT commands can’t be executed. The module logs off from network and enters POWER
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DOWN mode, and only the RTC is still active. POWER DOWN can also be indicated by VDD_EXT pin, which
is a low level voltage in this mode.
To monitor the temperature, the “AT+CMTE” command can be used to read the temperature when the module is
power on.
For details please refer to document [1]
3.4.3 Restart SIM900B Using the PWRKEY Pin
By driving the PWRKEY to a low level voltage for a short time and then release ,SIM900B can be restarted, the
timing is the same as turning on SIM900B using the PWRKEY pin. Before restarting the SIM900B, you need
delay at least 500ms from detecting the VDD_EXT low level on. The restarting scenario illustrates as the
following figure.
PWRKEY
（INPUT）
Delay > 500ms
Turn off
Restart
Pull down the PWRKEY
to turn on the module
VDD_EXT
（OUTPUT）
Figure 10: Timing of restart system
3.5 Power Saving
There are two methods for the module to enter into low current consumption status. “AT+CFUN” is used to set
module into minimum functionality mode and DTR signal can be used to control system enter or exit SLEEP
mode (or slow clocking mode).
3.5.1 Minimum Functionality Mode
Minimum functionality mode reduces the functionality of the module to a minimum and, thus, minimizes the
current consumption to the lowest level. This mode is set with the “AT+CFUN” command which provides the
choice of the functionality levels =0，1，4
z 0: minimum functionality;
z 1: full functionality (default);
z 4: disable phone both transmit and receive RF circuits;
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If SIM900B has been set to minimum functionality by “AT+CFUN=0”, the RF function and SIM card function
will be closed. In this case, the serial port is still accessible, but all AT commands correlative with RF function or
SIM card function will not be accessible.
If SIM900B has been set by “AT+CFUN=4”, the RF function will be closed, the serial port is still active. In this
case all AT commands correlative with RF function will not be accessible.
After SIM900B has been 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 document [1].
3.5.2 Sleep Mode (Slow Clock Mode)
DTR signal can be used to control SIM900B module to enter or exit the SLEEP mode in customer applications
When DTR is in high level and there is no on air and hardware interrupt (such as GPIO interrupt or data on serial
port), SIM900B will enter SLEEP mode automatically. In this mode, SIM900B can still receive paging or SMS
from network but the serial port is not accessible.
Note: For SIM900B, it requests to set AT command “AT+CSCLK=1” to enable the sleep mode; the default
value is 0, that can’t make the module enter sleep mode. For more details please refer to our AT command list.
3.5.3 Wake Up SIM900B from SLEEP Mode
When SIM900B is in SLEEP mode, the following methods can wake up the module.
z Enable DTR pin to wake up SIM900B.
If DTR pin is pulled down to a low level，this signal will wake up SIM900B from power saving mode. The
serial port will be active after DTR changed to low level for about 50ms.
z Receiving a voice or data call from network to wake up SIM900B.
z Receiving a SMS from network to wake up SIM900B.
3.6 Summary of State Transitions (except SLEEP mode)
The following figure shows how to proceed from one mode to another.
AT+CPOWD or Drive
PWRKEY to ground
Power Down
Power Down
Mode
Mode
Normal Mode
Normal Mode
Drive PWRKEY to ground
Figure 11: State Transition
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3.7 RTC Backup
The RTC (Real Time Clock) power supply of module can be provided by an external capacitor or a battery
(rechargeable or non-chargeable) through the VRTC.
Note: If the RTC function is enabled, a battery or capacitor should be connected with the VRTC pin. If this
function is not needed, a 4.7uF capacitor is recommended to connect to the VRTC pin.
The following figures show various sample circuits for RTC backup.
SIM900B
VRTC
10K
Non-chargeable
Backup Battery
RTC
Core
Figure 12: RTC supply from non-chargeable battery
SIM900B
VRTC
10K
RTC
Core
Rechargeable
Backup Battery
Figure 13: RTC supply from rechargeable battery
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SIM900B
VRTC
10K
RTC
Core
Large-capacitance
Capacitor
Figure 14: RTC supply from capacitor
z Li-battery backup
Coin-type Rechargeable Capacitor such as XH414H-IV01E form Seiko can be used.
Typical charge curves for each cell type are shown in following figures. Note that the rechargeable Lithium type
coin cells generally come pre-charged from the vendor.
Figure 15: Seiko XH414H-IV01E Charge Characteristic
3.8 Serial Interfaces
Table 7: Pin definition of the serial interfaces
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Serial port
Debug port
Name
Pin
Function
DCD
28
Data carrier detection
DTR
38
Data terminal ready
RXD
40
Receive data
TXD
42
Transmit data
RTS
44
Request to send
CTS
46
Clear to send
RI
48
Ring indicator
DBG_RXD
47
Receive data
DBG_TXD
49
Transmit data
SIM900B provides two unbalanced asynchronous serial ports. One is the serial port and the other is the debug port.
The GSM module is designed as a DCE (Data Communication Equipment), following the traditional DCE-DTE
(Data Terminal Equipment) connection. The module and the client (DTE) are connected through the following
signal (as following figure shows). Autobauding supports baud rate from 1200bps to 57600bps.
Serial port
z TXD: Send data to the RXD signal line of the DTE
z RXD: Receive data from the TXD signal line of the DTE
Debug port
z DBG_TXD: Send data to the RXD signal line of the DTE
z DBG_RXD: Receive data from the TXD signal line of the DTE
The logic levels are described in following table.
Table 8: Logic levels of the serial port and debug port
Parameter
Min
Max
Unit
VIL
0.15*VDD_EXT
VIH
0.85 *VDD_EXT
VDD_EXT
VOL
0.1
VOH
VDD_EXT -0.1
VDD_EXT
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MODULE (DCE)
CUSTOMER (DTE)
Serial port
Serial port1
TXD
TXD
RXD
RTS
CTS
DTR
DCD
RXD
RTS
CTS
DTR
DCD
RI
RING
Debug port
Serial port2
DBG_TX
TXD
RXD
DBG_RX
Figure 16: Connection of the serial interfaces
3.8.1 Function of serial port & debug port supporting
Serial port
z Modem device.
z Contains data lines TXD and RXD, State lines RTS and CTS, Control lines DTR, DCD and RI.
z Serial port can be used for CSD FAX, GPRS service and send AT command of controlling module. Also
serial port can be used for multiplexing function. SIM900B supports only basic mode of multiplexing so far.
z Serial port supports the communication rates as following:
1200, 2400, 4800, 9600, 19200, 38400, 57600 and 115200bps.
z Autobauding supports baud rates as following:
1200, 2400, 4800, 9600, 19200, 38400, and 57600bps，the default setting is autobauding。
Autobauding allows the GSM engine to automatically detect the baud rate configured in the host application. The
serial port of the GSM engine supports autobauding for the following baud rates: 1200, 2400, 4800, 9600, 19200,
38400, 57600bps. Factory setting is autobauding enabled. This gives you the flexibility to put the GSM engine
into operation no matter what baud rate your host application is configured to. To take advantage of autobauding
mode, specific attention should be paid to the following requirements:
Synchronization between DTE and DCE:
When DCE powers on with the autobauding enabled, user must first send “A” to synchronize the baud rate. It is
recommended to wait 2 to 3 seconds before sending “AT” character. After receiving the “OK” response, DTE
and DCE are correctly synchronized. The more information please refer to the AT command “AT+IPR”.
Restrictions on autobauding operation
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The serial port has to be operated at 8 data bits, no parity and 1 stop bit (factory setting).
The Unsolicited Result Codes like "RDY", "+CFUN: 1" and "+CPIN: READY” are not indicated when you
start up the ME while autobauding is enabled. This is due to the fact that the new baud rate is not detected
unless DTE and DCE are correctly synchronized as described above.
Note: use “AT+IPR=x “to set a fixed baud rate and save the configuration to non-volatile flash memory. After
the configuration is saved as fixed baud rate, the Unsolicited Result Codes like "RDY" should be received
from the serial port all the time that the SIM900B is power on.
Debug port
z Null modem port
z Only contain Data lines TXD and RXD
z Debug Port used for debugging and upgrading firmware. It cannot be used for CSD call, FAX call. And the
Debug port can not use multiplexing function. It does not support autobauding function.
z Debug port supports the communication rates is 115200bps
3.8.2 Software Upgrade and Software Debug
The DBG_TXD, DBG_RXD and GND must be connected to the IO connector when user need to upgrade
software and debug software, the DBG_TXD, DBG_RXD should be used for software upgrade and for software
debugging. The TXD and RXD also should be connected to the IO connector, if user wants to send AT command
or data stream to SIM900B. The PWRKEY pin is recommended to connect to the IO connector. The user also
can add a switch between the PWRKEY and the GND. The PWRKEY should be connected to the GND when
SIM900B is upgrading software. Please refer to the following figure.
MODULE(DCE)
DBG_TXD
TXD
DBG_RXD
RXD
GND
GND
PWRKEY
PWRKEY
I/O Connector
Serial port
Figure 17: Connection of software upgrade and software debug
The serial port and the debug port don’t support the RS_232 level and it only supports the CMOS level. Please
refer to the table 10 for details about the voltage level. You should add the level converter IC between the DCE
and DTE, if you connect it to the computer. Please refer to the following figure
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Figure 18: RS232 level converter circuit
3.9 Audio Interfaces
Table 9: Pin define of the Audio interface
(AIN1/AOUT1)
(AIN2/AOUT2)
Name
Pin
Function
MIC1P
53
Microphone1 input +
MIC1N
55
Microphone1 input -
SPK1P
54
Audio1 output+
SPK1N
56
Audio1 output-
MIC2P
57
Microphone2 input +
MIC2N
59
Microphone2 input -
SPK2P
58
Audio2 output+
SPK2N
60
Audio2 output-
The module provides two analogy input channels, AIN1 and AIN2, which may be used for both microphone and
line inputs. The electret microphone is recommended when the interface is used for microphone. One of the two
channels is typically used with a microphone built into a handset. The other channel is typically used with an
external microphone or external line input. The module analogy input configuration is determined by control
register settings and established using analogy multiplexes.
For each channels, “AT+CMIC” can be used to adjust the input gain level of microphone, “AT+SIDET” can be
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used to set the side-tone level. In addition, “AT+CLVL” can be used to adjust the output gain level of both
receiver and speaker at the same time, use AT+CHFA to activate one of the two audio channels and deactivate the
other one.. For more details, please refer to document [1].
Note: Use AT command AT+CHFA to select_audio channel:
0— AIN1/AOUT1 (normal audio channel), the default value is 0.
1— AIN2/AOUT2(aux_audio channel) .
It is suggested that you adopt one of the following two matching circuits in order to improve audio performance.
The difference audio signals have to be layout according to difference signal layout rules. As show in following
figures (Note: all components package are 0603.) If an amplifier circuit for audio is needed, then National
company’s LM4890 is recommended. Of course it can select it according to your requirement.
3.9.1 Speaker Interface Configuration
Figure 19: Speaker interface configuration
Figure 20: Speaker interface with amplifier configuration
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3.9.2 Microphone Interfaces Configuration
Close to Microphone
GND
GND
GND
Differential layout
ESD
ANTI
10pF
33pF
10pF
33pF
MICxP
MODULE
Electret
Microphone
MICxN
AGND
ESD
ANTI
33pF
10pF
AGND
GND
GND
GND
Figure 21: Microphone interface configuration
3.9.3 Earphone Interface Configuration
Close to Socket
Close to MODULE
Differential
layout
GND
33pF
33pF
MIC2N
MIC2P
GND
GND
GND
100R
MODULE
1uF
10R
SPK2P
SPK2N
33pF
33pF
GND
GND
10pF
33pF
Amphenol
GND
GND
GND
GND
GND
Figure 22: Earphone interface configuration
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3.9.4 Referenced Electronic Characteristic
Table 10: MIC Input Characteristics
Parameter
Min
Typ
Max
Unit
Working Voltage
1.2
1.5
2.0
Working Current
200
500
uA
External Microphone Load Resistance
1.2
2.2
Internal biasing DC Characteristics
Differential input
voltage
k Ohms
2.5
THD <1% at
F=1KHz; pre-amp
gain = 20 dB;
PGA gain = 14 dB
15.9
mVrms
THD <5% at
F=1KHz;pre-amp
gain = 0 dB; PGA
gain = 0 dB
740
mVrms
Table 11: Audio Output Characteristics
Parameter
Conditions
Min
Typ
Max
Unit
load Resistance
27
32
Ohm
Biasing voltage
Normal
Output(SPK1P/1N
Normal
Output(SPK2P/2N
1.4
Output swing
Voltage(single)
1.1V
Vpp
Output swing
Voltage(differentia
l)
2.2
Vpp
RL=32 Ohm
THD=0.1%
91
mW
RL=32 Ohm
THD=1%
96
mW
load Resistance
27
32
Ohm
Biasing voltage
1.4
Output swing
Voltage(single)
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Output swing
Voltage(differentia
l)
2.2
RL=32 Ohm
THD=0.1%
91
mW
RL=32 Ohm
THD=1%
96
mW
3.10 Buzzer
The BUZZER on the board-to-board connector can be used to drive a buzzer to indicate incoming call. The
output volume of buzzer can be set by “AT+CRSL”. The reference circuit for buzzer shown as following figure:
VBAT
MODULE
4.7K
BUZZER
47K
Figure 23: Reference circuit of Buzzer
Table 12: Buzzer Output Characteristics
Parameter
Min
Typ
Max
Unit
Working Voltage
2.4
2.85
3.0
Working Current
Load Resistance
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3.11 SIM Card Interface
3.11.1 SIM Card Application
The user can use AT Command to get information in SIM card. For more information, please refer to 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 (intended for use with a SIM application
Tool-kit).
Both 1.8V and 3.0V SIM Cards are supported.
The SIM interface is powered from an internal regulator in the module having normal voltage 3V. All pins reset
as outputs driving low. Logic levels are as described in table
Table 13: Pin define of the SIM interface
Name
Pin
Function
SIM_VDD
19
SIM Card Power output automatic output on SIM mode，
one is 3.0V±10%, another is 1.8V±10%. Current is about
10mA.
SIM_DATA
21
SIM Card data I/O
SIM_CLK
23
SIM Card Clock
SIM_RST
25
SIM Card Reset
SIM_PRESENCE
16
SIM Card Presence
Following is the reference circuit about SIM interface. We recommend an Electro-Static discharge device ST
(www.st.com ) ESDA6V1W5 or ON SEMI (www.onsemi.com ) SMF05C for “ESD ANTI”. The 22Ω resistors
showed in the following figure should be added in series on the IO line between the module and the SIM card for
protecting the SIM I/O port. The pull up resistor (about 15KΩ) on the SIM_DATA line already added in the
module. Note that the SIM peripheral circuit should be close to the SIM card socket.
The SIM_PRESENCE pin is used for detecting the SIM card insert or removal. The user can use the AT
command “AT+CSDT” to set the SIMCARD configuration. For detail of this AT command, please refer to
document [1]:
8 pins SIM card holder can be selected . The reference circuit about 8 pins SIM card holder illustrates as
following figure.
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220nF
SIM_VDD
MODULE
SIM_RST
22R
SIM_CLK
22R
MOLEX-91228
VCC
GND
RST
VPP
CLK
I/O
PRESENCE GND
SIM_PRESENCE
22R
SIM_DATA
SIM
CARD
SMF05C
22pF
Figure 24: Reference circuit of the 8 pins SIM card
If the SIM card detection function don’t use, the SIM_PRESENCE pin can be keep open. The reference circuit
about 6 pins SIM card illustrates as following figure.
220nF
SIM
CARD
SIM_VDD
MODULE
SIM_RST
22R
SIM_CLK
22R
SIM_DATA
22R
VCC
RST
CLK
GND
VPP
I/O
C707 10M006 512 2
22pF
SMF05C
Figure 25: Reference circuit of the 6 pins SIM card
3.11.2 Design Considerations for SIM Card Holder
For 6 pins SIM card holder, we recommend to use Amphenol C707 10M006 512 2, the user can visit
http://www.amphenol.com for more information about the holder.
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Figure 26: Amphenol C707 10M006 512 2 SIM card holder
Table 14: Pin description (Amphenol SIM card holder)
Pin Name
Signal
Description
C1
SIM_VDD
SIM Card Power supply, it can identify automatically the SIM Card power
mode，one is 3.0V±10%, another is 1.8V±10%. Current is about 10mA.
C2
SIM_RST
SIM Card Reset.
C3
SIM_CLK
SIM Card Clock.
C5
GND
Connect to GND.
C6
VPP
Not connect.
C7
SIM_DATA
SIM Card data I/O.
For 8 pins SIM card holder, Molex 91228 is recommended. The user can visit http://www.molex.com for more
information about the holder.
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Figure 27: Molex 91228 SIM card holder
Table 15: Pin description (Molex SIM card holder)
Pin Name
Signal
Description
C1
SIM_VDD
SIM Card Power supply, it can identify automatically the SIM Card power
mode，one is 3.0V±10%, another is 1.8V±10%. Current is about 10mA.
C2
SIM_RST
SIM Card Reset
C3
SIM_CLK
SIM Card Clock
C4
GND
Connect to GND
C5
GND
Connect to GND
C6
VPP
Not connect
C7
SIM_DATA
SIM Card data I/O
C8
SIM_PRESENCE
Detect SIM Card Presence
NOTE: the sim900B can support embedded SIM IC or embedded SIM card holder, but these functions
aren’t included in the default version, please contact SIMCom for more details.
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3.12 LCD Display Interface
SIM900B provides a serial LCD display interface that supports serial communication with LCD device.
When used as LCD interface, the following table is the pin definition. LCD interface timing should be united
with the LCD device.
Table 16: Pin define of the LCD interface
Name
Pin
Function
DISP_DATA
18
Display data output
DISP_CLK
20
Display clock for LCD
DISP_CS
22
Display enable
DISP_D/C
24
Display data or command select
DISP_RST
26
LCD reset
Note: This function is not supported in the default firmware. There must be some customized firmware if you
want. Please contact SIMCom for more details.
3.13 Keypad Interface
The keypad interface consists of 5 keypad column outputs and 4 keypad row inputs. The basic configuration is 5
keypad columns and 4 keypad rows, giving 20 keys.
Table 17: Pin define of the keypad interface
Name
Pin
KBC0
27
GPIO4/KBC1
29
GPIO3/KBC2
31
GPIO2/KBC3
33
GPIO1/KBC4
35
GPIO9/KBR1
39
GPIO8/KBR2
41
GPIO7/KBR3
43
GPIO6/KBR4
45
Function
Keypad matrix column
Keypad matrix row
The keypad interface allows a direct external matrix connection. A typical recommended circuit about the keypad
is as shown in the following figure.
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GND
KBC0
KBC1
KBC2
KBC3
KBC4
MODULE
KBR1
KBR2
KBR3
KBR4
Figure 28: Reference circuit of the keypad interface
*Note:
1. This function is not supported in the default firmware. There must be customized firmware if you want.
Please contact SIMCom for more details.
2.KBR0&KBC0 is used to power off the module, so do not connect them for other application.
3. keypad is the second function of this pin , the default function is GPIO.
3.14 ADC
SIM900B provides one auxiliary ADC (General purpose analog to digital converter.) as voltage input pin, which
can be used to detect the values of some external items such as voltage, temperature etc. We can use AT
command “AT+CADC” to read the voltage value on ADC. For detail of this AT command, please refer to
document [1].
Table 18: ADC specification
MIN
Type
MAX
Units
Voltage range
2.8
ADC Resolution
10
bits
Sampling rate
200K
Hz
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3.15 Behaviors of the RI
Table 19: Behaviours of the RI
State
RI respond
Standby
HIGH
Voice calling
Change LOW, then:
（1）Change to HIGH when establish calling.
（2）Use AT command ATH, the RI pin changes to HIGH.
（3）Sender hangs up, change to HIGH.
Data calling
Change LOW, then：
（1）Change to HIGH when establish calling.
（2）Use AT command ATH, the RI changes to HIGH.
SMS
When receive SMS, The RI will change to LOW and hold low level about 120 ms, then
change to HIGH.
URC
Some URCs triggers 120ms low level on RI. For more details, please refer to document [10]
If the module is used as caller, the RI will maintain high. However, when it is used as receiver, following is timing
of ring.
RI
HIGH
LOW
Power on
Ring
MO or MT
Hang up
Ring
Hang on
(talking)
MO or
MT
Hang up
Ring
Figure 29: SIM900B Services as Receiver
HIGH
RI
LOW
Power on
calling
Echo
talking
Hang up
calling
Echo
Hang up
Figure 30: SIM900B Services as caller
3.16 Network Status Indication
The NETLIGHT can be used to drive a network status indication LED lamp. The working state of this pin is
listed in following table:
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Table 20: Working state of the NETLIGHT
State
SIM900B function
Off
SIM900B is not running
64ms On/ 800ms Off
SIM900B does not find the network
64ms On/ 3000ms Off
SIM900B find the network
64ms On/ 300ms Off
GPRS communication
The reference circuit is shown as the following figure:
VBAT
MODULE
300R
4.7K
NETLIGHT
47K
Figure 31: Reference circuit of NETLIGHT
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3.17 General Purpose Input Output (GPIO)
SIM900B provides a limited number of General Purpose Input/Output signal pin.
Name
Pin
Function
RESET
GPIO0
32
General Purpose Input/Output Port
Input pull down
GPIO1/KBC4
35
Input pull down
GPIO2/KBC3
33
Input pull down
GPIO3/KBC2
31
Input pull down
GPIO4/KBC1
29
Input pull down
GPIO6/KBR4
45
Input pull down
GPIO7/KBR3
43
Input pull down
GPIO8/KBR2
41
Input pull down
GPIO9/KBR1
39
Table 21: Pin define of the GPIO interface
Input pull down
Note: This function is not supported in the default firmware. There must be special firmware if you require.
Please contact SIMCom for more details .
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4 Antenna Interface
The RF interface has an impedance of 50Ω. To suit the physical design of individual applications, SIM900B
offers alternatives:
Recommended approach: antenna connector on the component side of the PCB
Antenna pad and grounding plane placed on the bottom side.
Figure 32 : The RF interface of module
The antenna can be soldered to the pad, or attached via contact springs. To help you to ground the antenna,
SIM900B comes with a grounding plane located close to the antenna pad.
SIM900B material properties:
SIM900B PCB Material: FR4
Antenna pad: Gold plated pad
To minimize the loss on the RF cable, it need be very careful to choose RF cable. We recommend the insertion
loss should be meet following requirements:
z GSM900<1dB
z DCS1800/PCS1900<1.5dB
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4.1 Module RF Output Power
Table 22: SIM900B 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
4.2 Module RF Receive Sensitivity
Table 23: SIM900B conducted RF receive sensitivity
Frequency
Receive sensitivity（Typical）
Receive sensitivity(Max)
GSM850
-109dBm
-107dBm
EGSM900
-109dBm
-107dBm
DCS1800
-109dBm
-107dBm
PCS1900
-109dBm
-107dBm
4.3 Module Operating Frequencies
Table 24: SIM900B operating frequencies
Frequency
Receive
Transmit
GSM850
869
～ 894MHz
824
～ 849 MHz
EGSM900
925
～ 960MHz
880
～ 915MHz
DCS1800
1805 ～ 1880MHz
1710 ～ 1785MHz
PCS1900
1930 ～ 1990MHz
1850 ～ 1910MHz
5 Electrical, Reliability and Radio Characteristics
5.1 Absolute Maximum Ratings
The absolute maximum ratings stated in Table 28 are stress ratings under non-operating conditions. Stresses
beyond any of these limits will cause permanent damage to SIM900B.
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Table 25: Absolute maximum ratings
Parameter
Min
Max
Unit
VBAT
5.5
Peak current of power supply
3.0
Voltage at digit pins*
-0.3
3.1
II*
10
mA
IO*
10
mA
*For digital interface pins, such as keypad, GPIO, UART and LCD.
5.2 Operating Temperatures
The operating temperature is listed in following table:
Table 26: SIM900B operating temperature
Parameter
Min
Typ
Max
Unit
Ambient temperature
-30
+25
+80
℃
Restricted operation*
-40 to -30
+80 to +85
℃
Storage temperature
-45
+90
℃
* The SIM900B does work, but deviations from the GSM specification may occur.
5.3 Power Supply Ratings
Table 27: SIM900B power supply ratings
Parameter
Description
Conditions
Min
Typ
Max
Unit
VBAT
Supply voltage
Voltage must stay within the min/max
values, including voltage drop, ripple, and
spikes.
3.1
4.0
4.8
Voltage drop
during transmit
burst
Normal condition, power control level for
Pout max
300
mV
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Voltage ripple
IVBAT
Average
current
supply
Peak supply
current (during
Tx
burst)
Normal condition, power control level for
Pout max
@ f<200kHz
@ f>200kHz
50
POWER DOWN mode
SLEEP mode(BS-PA-MFRMS=2 )
(BS-PA-MFRMS=5 )
(BS-PA-MFRMS=9 )
50
1.5
1.2
1.0
uA
mA
mA
mA
IDLE mode
GSM 850
EGSM 900
DCS1800
PCS1900
22
22
22
22
TALK mode
GSM 850
EGSM 900
DCS1800
PCS1900
235
247
181
170
mA
DATA mode, GPRS (3 Rx,2Tx)
GSM 850
EGSM 900
DCS1800
PCS1900
436
463
322
303
mA
DATA mode, GPRS (4 Rx,1Tx)
GSM 850
EGSM 900
DCS1800
PCS1900
270
282
215
205
mA
Power control level for Pout max.
2.0
mA
5.4 Current Consumption
Please refer to the following table for the values of current consumption.
Table 28: SIM900B current consumption（VBAT=3.8V）
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Voice Call
GSM 850/EGSM 900
@power level #5 <300mA,Typical 250mA
@power level #12,Typical 110mA
@power level #19,Typical 80mA
DCS 1800/PCS 1900
@power level #0 <200mA,Typical 180mA
@power level #7,Typical 94mA
@power level #15,Typical 76mA
GPRS Data
DATA mode, GPRS ( 1 Rx,1 Tx ) CLASS 8
GSM 850/EGSM 900
@power level #5 <300mA,Typical 235mA
@power level #12,Typical 102mA
@power leve#19,Typical 74mA
DCS 1800/PCS 1900
@power level #0 <200mA,Typical 170mA
@power level #7,Typical 90mA
@power level #15,Typical 70mA
DATA mode, GPRS ( 3 Rx, 2 Tx ) CLASS 10
GSM 850/EGSM 900
@power level #5<450mA,Typical 440mA
@power level #12,Typical 185mA
@power level #19,Typical 125mA
DCS 1800/PCS 1900
@power level #0 <350mA,Typical 320mA
@power level #7,Typical 155mA
@power level #15,Typical 120mA
DATA mode, GPRS ( 4 Rx,1 Tx ) CLASS 8
GSM 850/EGSM 900
@power level #5 <300mA,Typical 273mA
@power level #12,Typical 145mA
@power level #19,Typical 120mA
DCS 1800/PCS 1900
@power level #0<300mA,Typical 205mA
@power level #7,Typical 130mA
@power level #15,Typical 110mA
Class 10 is default set when the module works at data translation mode, the module can also work at class 8 set by
AT command.
5.5 Electro-Static Discharge
The GSM engine is not protected against Electrostatic Discharge (ESD) in general. Therefore, it is subject to ESD
handing precautions that typically apply to ESD sensitive components. Proper ESD handing and packaging
procedures must be applied throughout the processing, handing and operation of any application using a SIM900B
module.
The measured values of SIM900B are shown as the following table:
Table 29: The ESD endure statue measured table (Temperature: 25℃, Humidity:45% )
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Part
Contact discharge
Air discharge
VBAT
±5KV
±10KV
GND
±5KV
±10KV
RXD, TXD
±2KV
±8KV
Antenna port
±5KV
±10KV
SPK_P/N
MIC_P/N
±4KV
±8KV
PWRKEY
±2KV
±8KV
Other port
TBD
TBD
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6 Mechanics
This chapter describes the mechanical dimensions of SIM900B.
6.1 Mechanical Dimensions of SIM900B
Following shows the Mechanical dimensions of SIM900B (top view, side view and bottom view).
Figure 33: Top an Side Mechanical dimensions of module （Unit: mm）
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Figure 34：Mechanical dimensions of module PCB decal（Unit: mm）
6.2 Top View of the SIM900B
Figure 35: Top view of the SIM900B
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6.3 Mounting SIM900B onto the application platform
Use the connector SUNCAGEY BB530-06001-20R to fix the SIM900B onto the customer platform
6.4 Board-to-board connector
We recommend to use SUNCAGEY Company’s BB530-06001-20R as the board-to-board connector. They are
fully compatible each other. This high density SMT connector is designed for parallel PCB-to-PCB applications.
It is ideal to use in VCRs, notebook PCs, cordless telephones, mobile phones, audio/visual and other
telecommunications equipment where reduced size and weight are important. Following is parameter of
BB530-06001-20R. For more details, you can login http://www.suncagey.com for more information.
6.4.1 Mechanical dimensions of the SUNCAGEY BB530-06001-20R
Figure 36: SUNCAGEY BB530-06001-20R board-to-board connector
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Figure 37 Board-to-board connector physical photo
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6.5 RF connector
The RF connector in module side is a ultra small surface mount coaxial connectors (Part Number: U.FL-R-SMT,
vended by HRS). It has high performance with wide frequency range, surface mountable and reflows solderable.
Following is parameter (Figure 36). Certainly the user can visit http://www.hirose-connectors.com/ for more
information.
To get good RF performance in customer’s design, we suggest the customer to use the matching RF adapter cable
which is also supplied by HRS (Part Number: U.FL-LP（V）-040), the following figure 41 is the dimensions of
U.FL series RF adapter cable. The customer can get it from the cable’s manufacturer HRS, and for details, please
visit http://www.hirose-connectors.com/.
Unit:mm
Figure 38: U.FL-R-SMT
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Unit:mm
Figure 39: U.FL series RF adapter cable
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6.6 PIN Assignment of SIM900B
Table 30: PIN assignment
PIN NO.
PIN NAME
I/O
PIN NO.
PIN NAME
I/O
VBAT
VBAT
VBAT
VBAT
VBAT
VBAT
VBAT
VBAT
GND
10
GND
11
GND
12
GND
13
GND
14
GND
15
VRTC
I/O
16
SIM_PRESENCE
17
VDD_EXT
18
DISP_DATA
I/O
19
SIM_VDD
20
DISP_CLK
21
SIM_DATA
I/O
22
DISP_CS
23
SIM_CLK
24
DISP_D/C
25
SIM_RST
26
DISP_RST
27
KBC0
28
DCD
29
GPIO4/KBC1
I/O
30
NETLIGHT
31
GPIO3/KBC2
I/O
32
GPIO0
I/O
33
GPIO2/KBC3
I/O
34
PWRKEY
35
GPIO1/KBC4
I/O
36
BUZZER
37
KBR0
38
DTR
39
GPIO9/KBR1
I/O
40
RXD
41
GPIO8/KBR2
I/O
42
TXD
43
GPIO7/KBR3
I/O
44
RTS
45
GPIO6/KBR4
I/O
46
CTS
47
DBG_RXD
48
RI
49
DBG_TXD
50
AGND
51
AGND
52
ADC0
53
MIC1P
54
SPK1P
55
MIC1N
56
SPK1N
57
MIC2P
58
SPK2P
59
MIC2N
60
SPK2N
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Contact us:
Shanghai SIMCom Wireless Solutions Ltd.
Add: SIM Technology Building，No.633，Jinzhong Road，Changning District，Shanghai P.R. China
200335
Tel: +86 21 3235 3300
Fax: +86 21 3235 3301
URL: www.sim.com/wm
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Modify Date                     : 2010:06:25 16:06:58+08:00
Create Date                     : 2010:06:25 16:01:56+08:00
Metadata Date                   : 2010:06:25 16:06:58+08:00
Document ID                     : uuid:ad73300a-8e67-4627-b0ba-af96ea4a8599
Instance ID                     : uuid:7ab107d4-f981-4ed8-8a3c-d3b2dd25e4cf
Subject                         : 2
Format                          : application/pdf
Creator                         : cheng.shi
Title                           : 
Page Count                      : 62
Page Layout                     : OneColumn
Author                          : cheng.shi

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Simcom 1005242010007 SIM900B Wireless Module User Manual

Shanghai Simcom Ltd. SIM900B Wireless Module

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User Manual

FCC ID Filing: UDV-1005242010007

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