Hardware Design
SIM548C_HD_V1.01
SIM548C Hardware Design
Document Title:
Version:
Date:
Status:
Document Control ID:
SIM548C Hardware Design
1.01
2008-05-09
Release
SIM548C_HD_V1.01
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. 2008
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Contents
Contents ............................................................................................................................................3
Version History.................................................................................................................................9
Scope of the document......................................................................................................................9
1 Introduction..................................................................................................................................10
1.1 Related documents .............................................................................................................10
1.2 Terms and abbreviations ....................................................................................................11
2 Overview......................................................................................................................................14
2.1 Key features .......................................................................................................................15
2.2 Functional diagram.............................................................................................................17
2.3 Evaluation board ................................................................................................................18
3 GSM application interface ...........................................................................................................19
3.1 Pin description....................................................................................................................19
3.2 Operating modes ................................................................................................................21
3.3 Power supply ......................................................................................................................23
3.3.1 Power supply pins on the board-to-board connector................................................25
3.3.2 Minimizing power losses..........................................................................................25
3.3.3 Monitoring power supply .........................................................................................25
3.4 Power up and down scenarios ............................................................................................25
3.4.1 Turn on the GSM part...............................................................................................25
3.4.2 Turn off the GSM part..............................................................................................29
3.4.3 Restart the GSM part using the PWRKEY pin.........................................................32
3.5 Charging interface..............................................................................................................32
3.5.1 Battery pack characteristics......................................................................................33
3.5.2 Recommended battery pack .....................................................................................34
3.5.3 Implemented charging technique..............................................................................35
3.5.4 Operating modes during charging ............................................................................36
3.5.5 Charger requirements ...............................................................................................38
3.6 Power saving ......................................................................................................................38
3.6.1 Minimum functionality mode...................................................................................38
3.6.2 SLEEP mode (slow clock mode)..............................................................................39
3.6.3 Wake up the GSM part from SLEEP mode..............................................................39
3.7 Summary of state transitions (except SLEEP mode) .........................................................40
3.8 RTC backup........................................................................................................................41
3.9 GSM Serial interface..........................................................................................................44
3.9.1 Function of serial port & debug port supporting......................................................46
3.9.2 Software upgrade and software debug......................................................................47
3.10 Audio interfaces ...............................................................................................................49
3.10.1 Speaker interface configuration..............................................................................50
3.10.2 Microphone interfaces configuration......................................................................51
3.10.3 Earphone interface configuration ...........................................................................52
3.10.4 Referenced electronic characteristic.......................................................................52
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3.11 SIM interface....................................................................................................................53
3.11.1 SIM card application ..............................................................................................53
3.11.2 Design considerations for SIM card holder ............................................................55
3.12 LCD interface...................................................................................................................57
3.13 ADC .................................................................................................................................58
3.14 General purpose input & output(GPIO) ...........................................................................58
3.15 Behaviors of the RI line (serial port1 interface only).......................................................58
3.16 Network status indication.................................................................................................60
3.17 Buzzer ..............................................................................................................................60
4 GPS application interface.............................................................................................................62
4.1 Theory of operation............................................................................................................62
4.2 Technical data.....................................................................................................................63
4.3 Pin description....................................................................................................................64
4.4 Turn on the GPS part..........................................................................................................66
4.5 The theory of the GPS RTC circuit ....................................................................................67
4.6 The theory of the RESET Circuit .......................................................................................68
4.7 GPS operation modes.........................................................................................................69
4.8 Serial interface of the GPS part..........................................................................................69
4.9 Start-up procedure..............................................................................................................70
4.9.1 Coldstart ...................................................................................................................70
4.9.2 Warmstart .................................................................................................................70
4.9.3 Hotstart.....................................................................................................................71
5 Antenna interface.........................................................................................................................72
5.1 GSM Antenna.....................................................................................................................72
5.1.1 GSM Antenna connector..........................................................................................72
5.1.2 GSM Antenna pad....................................................................................................72
5.1.3 Module RF output power..........................................................................................74
5.1.4 Module RF receive sensitivity..................................................................................74
5.1.5 Module operating frequencies..................................................................................74
5.2 GPS Antenna ......................................................................................................................74
5.2.1 GPS Antenna Connection.........................................................................................74
5.2.2 GPS Antenna Choice Consideration ........................................................................75
6 Electrical, reliability and radio characteristics .............................................................................77
6.1 Absolute maximum ratings.................................................................................................77
6.2 Operating temperatures ......................................................................................................77
6.3 Power supply rating............................................................................................................78
6.4 Current consumption..........................................................................................................79
6.4.1 The current consumption of the GSM part...............................................................79
6.4.2 The current consumption of the GPS part ................................................................80
6.5 Electrostatic discharge........................................................................................................83
7 Mechanics ....................................................................................................................................85
7.1 Mechanical dimensions......................................................................................................85
7.2 Mounting the module onto the application platform..........................................................86
7.3 Board-to-board connector ..................................................................................................86
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7.3.1 Mechanical dimensions of the ASTRON 1590060-09T-R.......................................87
7.3.2 Adapter cabling ........................................................................................................88
APPENDIX A: PIN assignment of board-to-board connector........................................................89
APPENDIX B: Reference Circuit with external MCU (GPS standalone application) ...................91
APPENDIX C: Reference Diagram with external MCU (AGPS application)................................92
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Table Index
TABLE 1: RELATED DOCUMENTS...................................................................................................10
TABLE 2: TERMS AND ABBREVIATIONS .......................................................................................11
TABLE 3: KEY FEATURES..................................................................................................................15
TABLE 4: CODING SCHEMES AND MAXIMUM NET DATA RATES OVER AIR INTERFACE.. 17
TABLE 5: BOARD-TO-BOARD CONNECTOR PIN DESCRIPTION ...............................................19
TABLE 6: OVERVIEW OF OPERATING MODES..............................................................................22
TABLE 7: AT COMMANDS USED IN ALARM MODE ..................................................................... 29
TABLE 8: RECOMMENDED BATTERY PROTECT CIRCUIT PARAMETER.................................34
TABLE 9: SPEC OF RECOMMENDED BATTERY PACK.................................................................34
TABLE 10: OPERATING MODES .......................................................................................................37
TABLE 11: AT COMMAND USUALLY USED IN GHOST MODE ...................................................37
TABLE 12: SUMMARY OF STATE TRANSITIONS...........................................................................40
TABLE 13: PIN DEFINITION OF THE SERIAL INTERFACES ........................................................44
TABLE 14: LOGIC LEVELS OF SERIAL PORTS PINS.....................................................................45
TABLE 15: PIN DEFINITION OF THE AUDIO INTERFACE............................................................49
TABLE 16: MIC INPUT CHARACTERISTICS ................................................................................... 52
TABLE 17: SPK OUTPUT CHARACTERISTICS ...............................................................................52
TABLE 18: PIN DEFINITION OF SIM INTERFACE (BOARD-TO-BOARD CONNECTOR) ......... 54
TABLE 19: PIN DEFINITION (AMPHENOL SIM CARD HOLDER)................................................56
TABLE 20: PIN DEFINITION (MOLEX SIM CARD HOLDER)........................................................57
TABLE 21: PIN DEFINITION OF THE LCD INTERFACE ................................................................57
TABLE 22: ADC SPECIFICATION ......................................................................................................58
TABLE 23: PIN DESCRIPTION OF THE GPIO INTERFACE............................................................58
TABLE 24: BEHAVIOURS OF THE RI LINE......................................................................................58
TABLE 25: WORKING STATE OF THE NETLIGHT .........................................................................60
TABLE 26: BUZZER OUTPUT CHARACTERISTICS....................................................................... 61
TABLE 27: PIN DEFINITION ..............................................................................................................64
TABLE 28: CONSOLIDATED PIN CHARACTERISTICS..................................................................66
TABLE 29: GPS OPERATION MODES ...............................................................................................69
TABLE 30: THE GSM PART CONDUCTED RF OUTPUT POWER..................................................74
TABLE 31: CONDUCTED RF RECEIVE SENSITIVITY OF THE GSM PART ................................74
TABLE 32: THE GSM PART OPERATING FREQUENCIES..............................................................74
TABLE 33: ABSOLUTE MAXIMUM RATINGS (GSM PART)..........................................................77
TABLE 34: ABSOLUTE MAXIMUM RATINGS (GPS PART)...........................................................77
TABLE 35: OPERATING TEMPERATURE.........................................................................................78
TABLE 36: POWER SUPPLY RATING (GSM PART)......................................................................... 78
TABLE 37: POWER SUPPLY RATING (GPS PART) ..........................................................................79
TABLE 38: CURRENT CONSUMPTION (GSM PART) .....................................................................79
TABLE 39: THE ESD ENDURE STATUE MEASURED TABLE (TEMPERATURE: 25℃,
HUMIDITY: 45% ) ........................................................................................................................ 84
TABLE 40: PIN ASSIGNMENT............................................................................................................89
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Figure Index
FIGURE 1: FUNCTIONAL DIAGRAM ...............................................................................................18
FIGURE 2: REFERENCE CIRCUIT OF THE VBAT INPUT ..............................................................23
FIGURE 3: REFERENCE CIRCUIT OF THE SOURCE POWER SUPPLY INPUT........................... 24
FIGURE 4: VBAT VOLTAGE DROP DURING TRANSMIT BURST ................................................24
FIGURE 5: TURN ON GSM PART USING DRIVING CIRCUIT .......................................................26
FIGURE 6: TURN ON GSM PART USING BUTTON.........................................................................26
FIGURE 7: TIMING OF TURN ON GSM PART..................................................................................27
FIGURE 8: TIMING OF TURN OFF GSM PART................................................................................30
FIGURE 9: TIMING OF RESTART GSM PART.................................................................................. 32
FIGURE 10: BATTERY CHARGER AND PACK ................................................................................33
FIGURE 11: RTC SUPPLY FROM NON-CHARGEABLE BATTERY ...............................................41
FIGURE 12: RTC SUPPLY FROM RECHARGEABLE BATTERY ....................................................42
FIGURE 13: RTC SUPPLY FROM CAPACITOR ................................................................................42
FIGURE 14: PANASONIC EECEMOE204A CHARGE CHARACTERISTIC ...................................43
FIGURE 15: MAXELL TC614 CHARGE CHARACTERISTIC..........................................................43
FIGURE 16: SEIKO TS621 CHARGE CHARACTERISTIC ............................................................... 44
FIGURE 17: CONNECTION OF THE SERIAL INTERFACES ..........................................................46
FIGURE 18: CONNECTION OF SOFTWARE UPGRADE.................................................................48
FIGURE 19: CONNECTION OF SOFTWARE DEBUG......................................................................48
FIGURE 20: RS232 LEVEL CONVERTER CIRCUIT.........................................................................49
FIGURE 21: SPEAKER INTERFACE CONFIGURATION .................................................................50
FIGURE 22: SPEAKER INTERFACE WITH AMPLIFIER CONFIGURATION................................ 51
FIGURE 23: MICROPHONE INTERFACE CONFIGURATION ........................................................51
FIGURE 24: EARPHONE INTERFACE CONFIGURATION..............................................................52
FIGURE 25: SIM INTERFACE REFERENCE CIRCUIT WITH 8-PIN SIM CARD ..........................54
FIGURE 26: SIM INTERFACE REFERENCE CIRCUIT WITH 6-PIN SIM CARD ..........................55
FIGURE 27: AMPHENOL C707-10M006 512 2 SIM CARD HOLDER .............................................55
FIGURE 28: MOLEX 91228 SIM CARD HOLDER ............................................................................56
FIGURE 29: THE GSM PART SERVICES AS RECEIVER................................................................. 59
FIGURE 30: THE GSM PART SERVICES AS CALLER.....................................................................59
FIGURE 31: REFERENCE CIRCUIT OF NETLIGHT ........................................................................60
FIGURE 32: REFERENCE CIRCUIT OF BUZZER ............................................................................61
FIGURE 33: THEORY OF OPERATION.............................................................................................. 62
FIGURE 34: TURN ON THE GPS MODULE ......................................................................................67
FIGURE 35: THEORY OF THE GPS RTC CIRCUIT ..........................................................................68
FIGURE 36: THEORY OF THE RESET CIRCUIT..............................................................................68
FIGURE 37: RF CONNECTOR AND RF PAD..................................................................................... 73
FIGURE 38: RF CONNECTOR ............................................................................................................75
FIGURE 39: POWER DOWN MODE...................................................................................................81
FIGURE 40: PUSH-TO-FIX MODE .....................................................................................................82
FIGURE 41: POWER CONSUMPTION IN THE PTF MODE.............................................................83
FIGURE 42: MECHANICAL DIMENSIONS OF MODULE（UNIT: MM） ....................................85
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FIGURE 43: MOUNT THE MODULE（UNIT: MM）.......................................................................86
FIGURE 44: MECHANICAL DIMENSIONS OF MODULE PCB DECAL（UNIT: MM）..............86
FIGURE 45: ASTRON1590060-09T-R BOARD TO BOARD CONNECTOR.....................................87
FIGURE 46: ASTRON BOARD TO BOARD CONNECTOR PHYSICAL PHOTO ...........................87
FIGURE 47: MM9329-2700B................................................................................................................ 88
FIGURE 48: RF CONNECTOR MXTK................................................................................................88
FIGURE 49: PHYSICAL SIM548C.......................................................................................................90
FIGURE 50: REFERENCE CIRCUIT WITH EXTERNAL MCU (STANDALONE APPLICATION
FOR EXAMPLE)...........................................................................................................................91
FIGURE 51: AGPS CONNECTION...................................................................................................... 92
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Version History
Date Version Description of change Author
2008-05-09 1.01 Origin Tanshi
Scope of the document
This document is intended for the following versions of the SIMCom GSM/GPRS&GPS modules
•SIM548C: GSM/GPRS 850/900/1800 /1900MHz Version
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1 Introduction
This document describes the hardware interface of the SIMCom SIM548C module that connects
to the specific application and the air interface. As SIM548C can be integrated with a wide range
of applications, all functional components of SIM548C are described in great detail.
This document can help you quickly understand SIM548C interface specifications, electrical and
mechanical details. With the help of this document and other application notes, user guide, you
can use SIM548C module to design and set-up mobile applications quickly.
1.1 Related documents
Table 1: Related documents
SN Document name Remark
[1]
[2]
[3]
[4]
[5]
[6]
[7]
SIM548C_ATC SIM548C_ATC
GPS_AN01 GPS_AN01_GPS_Command_Examples
GPS_AN02 GPS_AN02_AGPS_Application
ITU-T Draft new
recommendation
V.25ter:
GSM 07.07: Digital cellular telecommunications (Phase 2+); AT command
GSM 07.05: Digital cellular telecommunications (Phase 2+); Use of Data
GSM 07.10: Support GSM 07.10 multiplexing protocol
Serial asynchronous automatic dialing and control
set for GSM Mobile Equipment (ME)
Terminal Equipment – Data Circuit terminating Equipment
(DTE – DCE) interface for Short Message Service (SMS) and
Cell Broadcast Service (CBS)
[8]
[9]
SIM548C_HD_V1.01 09.05.2008
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
GSM 11.11: Digital cellular telecommunications system (Phase 2+);
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SIM548C Hardware Design
Specification of the Subscriber Identity Module – Mobile
Equipment (SIM – ME) interface
[10]
GSM 03.38: Digital cellular telecommunications system (Phase 2+);
Alphabets and language-specific information
[11]
GSM 11.10
Digital cellular telecommunications system (Phase 2) ；
Mobile Station (MS) conformance specification； Part 1:
Conformance specification
[12]
AN SerialPport AN SerialPport
1.2 Terms and abbreviations
Table 2: Terms and abbreviations
GSM PART
Abbreviation Description
ADC Analog-to-Digital Converter
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
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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
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)
RP Receive Protocol
RTC Real Time Clock
Rx Receive Direction
SA Selective Availability
SAR Specific Absorption Rate
SIM Subscriber Identification Module
SMS Short Message Service
TDMA Time Division Multiple Access
TE Terminal Equipment, also referred to as DTE
TX Transmit Direction
URC Unsolicited Result Code
USSD Unstructured Supplementary Service Data
VSWR Voltage Standing Wave Ratio
Vmax Maximum Voltage Value
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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
Phonebook abbreviations
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)
ME Mobile Equipment phonebook
RC Mobile Equipment list of received calls
SM SIM phonebook
DC ME dialed calls list(+CPBW may not be applicable or this storage)(same as LD)
LA Last Number All list (LND/LNM/LNR)
ON SIM (or ME) own numbers (MSISDNs) list
SD SIM service dial number
VM SIM voice mailbox
BN SIM barred dialed number
GPS PART
Abbreviation Description
ATP Adaptive Trickle Power mode.
DGPS Differential GPS
GGA GPS Fixed Data
GPS Global Positioning System
LNA Low Noise Amplifier
RTCM Radio Technical Commission for Maritime Services
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2 Overview
Designed for global market, SIM548C is a GSM/GPRS and GPS module. SIM548C with a
Quad-band GSM/GPRS engine works on frequencies EGSM 900 MHz/DCS 1800 MHz and
GSM850 MHz/PCS 1900 MHz. SIM548C also supports GPS technology for satellite navigation.
SIM548C provides GPRS multi-slot class10 / class 8 (option) capabilities and supports the GPRS
coding schemes CS-1, CS-2, CS-3 and CS-4.
With a tiny configuration of 50mm x 33mm x 8.8mm, SIM548C can meet almost all the space
requirement in your application, such as M2M, smart phone, PDA phone, GPS hand-held device and
other mobile device, or applications of AVL (Automated Vehicle Location), location service and
so on.
The physical interface to the mobile application is an 60-pin board-to-board connector, which
provides all hardware interfaces between the module and customers’ boards except the RF antenna
interface.
z The SPI display interface will give you the flexibility to develop customized applications.
z One serial GSM port and two serial GPS pots can help you easily develop your applications.
z Two audio channels include two microphones inputs and two speakers’ outputs. These can be
easily configured by AT command.
z Charge interface
With the charge circuit integrated inside the SIM548C, it is very suitable for the battery power
application.
SIM548C provides GSM RF antenna interface with alternatives: antenna connector and antenna
pad. The antenna connector is MURATA MM9329-2700 RA1. And customer’s antenna can be
soldered to the antenna pad. A separate GPS antenna must be connected to the GPS part of the
module in order to properly receive satellite data.
The SIM548C is designed with power saving technique, so that the current consumption of GSM
part maintains is as low as about 3mA in SLEEP mode.
The SIM548C 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.
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The SIM548C is fully RoHS compliant to EU regulation.
2.1 Key features
Table 3: Key features
Feature Implementation
Power supply z GSM part: Supply voltage 3.4V – 4.5V
z GPS part: Separate power supply source: 3.3V ± 5%
Power saving z GSM part: Typical power consumption in SLEEP mode to
3.5mA ( BS-PA-MFRMS=5 )
z GPS part: Power Down mode / Push-to-Fix mode
Charging Supports charging control for Li-Ion battery
Frequency bands
z EGSM 900/DCS 1800 and GSM850 MHz/PCS 1900 MHz. The
SIM548C can search the frequency bands automatically. The
frequency bands also can be set by AT command.
z Compliant to GSM Phase 2/2+
GSM class Small MS
Transmitting power z Class 4 (2W) at EGSM 900/GSM 850
z Class 1 (1W) at DCS 1800/PCS 1900
GPRS connectivity
z GPRS multi-slot class 10 (default)
z GPRS multi-slot class 8 (option)
z GPRS mobile station class B
GPS features z GPS receiver with SiRFstar III chip set
z Processor type ARM7/TDMI
Temperature range
z Operation Temperature:
Normal operation: -30°C to +80°C
Restricted operation: -40°C to -30°C and +80°C to +85°C
(1)
z Storage temperature -45°C to +90°C
DATA GPRS:
SIM548C_HD_V1.01 09.05.2008
z GPRS data downlink transfer: max. 85.6 kbps
z GPRS data uplink transfer: max. 42.8 kbps
z Coding scheme: CS-1, CS-2, CS-3 and CS-4
z SIM548C supports the protocols PAP (Password Authentication
Protocol) usually used for PPP connections.
z The SIM548C integrates the TCP/IP protocol.
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SIM548C Hardware Design
CSD:
z Support Packet Switched Broadcast Control Channel (PBCCH)
z CSD transmission rates: 2.4, 4.8, 9.6, 14.4 kbps,
non-transparent
z Unstructured Supplementary Services Data (USSD) support
SMS z MT, MO, CB, Text and PDU mode
z SMS storage: SIM card
FAX Group 3 Class 1
SIM interface Support SIM card: 1.8V ,3V
External antenna z GSM part: Connected via 50 Ohm antenna connector or antenna
pad
z GPS part: Separate GPS antenna connector. Please refer to
figure 33 for details
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
Serial GSM port and
Debug port
z Serial port: Seven lines on Serial Port Interface
z Serial Port can be used for CSD FAX, GPRS service and send
AT command of controlling module.
z Serial Port can use multiplexing function
z Autobauding supports baud rate from 4800 bps to 115200bps.
z Debug Port: Two lines on debug port interface DBG_TXD
and DBG_RXD
z Debug Port only used for debugging
Two serial GPS port z Serial Port A: Two lines on Serial Port A, GPS_TXA and
GPS_RXA
z Serial Port B: Two lines on Serial Port B, GPS_TXB and
GPS_RXB
Phonebook management Support phonebook types: SM, FD, LD, MC, RC, ON,
ME,BN,VM,LA,DC,SD
SIM Application Toolkit Support SAT class 3, GSM 11.14 Release 99
Real time clock Implemented
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Timer function Programmable via AT command
Physical characteristics Size: 50±0.15 x 33±0.15 x10.3±0.3mm (including application
connector)
50±0.15 x 33±0.15 x 8.8±0.3mm (excluding application
connector)
Weight: 16.5g
Firmware upgrade Firmware upgrade by serial port
(1) The module does work, but deviations from the GSM specification may occur, For example,
both the frequency error and the phase error will be large.
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 Functional diagram
The SIM548C have two circuits parts (GSM part and GPS part) which are place on one PCB and
have only one connector .The following figure shows a functional diagram of the SIM548C and
illustrates the mainly functional part:
GSM 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
GPS part:
z The SIRFIII GPS engine
z The GPS radio frequency part
z The antenna interface
z The board-to-board interface
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SIM548C Hardware Design
Figure1:Functionaldiagram
2.3 Evaluation board
In order to help you on the application of SIM548C, SIMCom can supply an Evaluation Board
(EVB) that interfaces the SIM548C directly with appropriate power supply, SIM card holder,
RS232 serial port, handset port, earphone port, antenna and all GPIOs of the SIM548C.
For details please refer to the SIM548C-EVB_UGD document.
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SIM548C Hardware Design
3 GSM application interface
All hardware interfaces except RF interface that connects SIM548C to the customers’ cellular
application platform is through a 60-pin 1.27mm pitch board-to-board connector. Sub-interfaces
included in this board-to-board connector are described in detail in following chapters:
z Power supply and charging control
z GSM serial interface
z Two analog audio interfaces
z SIM interface
Electrical and mechanical characteristics of the board-to-board connector are specified in Chapter
6. There are also ordering information for mating connectors.
3.1 Pin description
Table 5: Board-to-Board connector pin description
Power Supply
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS
VBAT
VRTC I/O
4 VBAT pins of the board-to-board
connector are dedicated to connect
the supply voltage. The power supply
of the GSM part of 548C has to be a
single voltage source of VBAT=
3.4V...4.5V. It must be able to provide
sufficient current in a transmitting
burst which typically rises to
2A.mostly. These 4 pins are voltage
input
RTC current input from the backup
battery when the VBAT is not
supplied for the system.
Current output to backup battery
when the main battery is present and
the backup battery is low voltage
state.
Vmax= 4.5V
Vmin=3.4V
Vnorm=4.0V
Vmax=2.0V
Vmin=1.2V
Vnorm=1.8V
Iout(max)= 20uA
Iin=5 uA
VCHG I
SIM548C_HD_V1.01 09.05.2008
Voltage input for the charge circuit;
making the system detect the charger.
19
Vmax=5.25V
Vmin=1.1 * VBAT
Vnorm=5.1V
SIM548C Hardware Design
GND Digital ground
Power on or power off
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS
PWRKEY I
Voltage input for PWRKEY.
PWRKEY should be pull low to
power on or power off the system.
VILmax=0.2*VBAT
VIHmin=0.6*VBAT
VImax=VBAT
The user should keep pressing the
key for a moment when power on or
power off the system. because the
system need margin time in order to
assert the software.
Audio interface
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS
MIC1P
MIC1N
MIC2P
MIC2N
SPK1P
SPK1N
SPK2P
SPK2N
I Positive and negative voice-band
input
I Auxiliary positive and negative
voice-band input
O Positive and negative voice-band
output
O Auxiliary positive and negative
voice-band output
Audio DC Characteristics
refer to chapter 3.9.4
BUZZER O Buzzer output
AGND Analog ground
Display interface
DISP_DATA I/O
DISP_CLK O
LCD display interface
VILmin=0V
VILmax=0.9V
VIHmin=2.0V
DISP_D/C O
DISP_CS O
DISP_RST O
VIHmax= 3.2V
VOLmin=GND
VOLmax=0.2V
VOHmin=2.7V
VOHmax=2.9V
GERNERAL PURPOSE input/output
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS
NETLIGHT O Network status indication
STATUS O Another indication for system on/off
GPIO0 I/O General purpose input/output port
VILmin=0V
VILmax=0.9V
VIHmin=2.0V
VIHmax= 3.2V
GPIO1 I/O General purpose input/output port
VOLmin=GND
VOLmax=0.2V
VOHmin=2.7V
VOHmax=2.9V
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Serial port
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS
DTR I Data terminal ready
RXD I Receive data
TXD O Transmit data
RTS I Request to send
CTS O Clear to send
RI O Ring indicator
VILmin=0V
VILmax=0.9V
VIHmin=2.0V
VIHmax= 3.2V
VOLmin=GND
VOLmax=0.2V
VOHmin=2.7V
DCD O Data carrier detection
VOHmax=2.9V
Debug port
DBG_TXD O
Serial interface for debugging only
DBG_RXD I
SIM interface
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS
SIM_VDD O 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
VILmin=0V
VILmax=0.3* SIM_VDD
SIM_CLK O SIM clock
VIHmin=0.7* SIM_VDD
VIHmax= SIM_VDD +0.3
SIM_PRESENCE I SIM card detection
SIM_RST O SIM reset
VOLmin=GND
VOLmax=0.2V
VOHmin= SIM_VDD -0.2
VOHmax= SIM_VDD
AUXADC
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS
ADC0 I
TEMP_BAT I
General purpose analog to digital
converter.
For measure the battery temperature 0-1.2V
Input voltage range: 0V to
2.4V
3.2 Operating modes
The table below briefly summarizes the various operating modes referred to in the following
chapters.
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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 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.
During SLEEP mode, the module can still receive paging
message and SMS from the system normally.
GSM IDLE Software is active. Module has registered to the GSM network,
and the module is ready to send and receive.
GSM TALK Connection is going on between two subscribers. 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 in transfer (PPP or TCP or UDP). 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” command or using the
PWRKEY. 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 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 and the SIM card will not be accessible,or both RF part and SIM
card will be closed all, and the serial port is still accessible. The power
consumption in this case is very low.
Alarm mode RTC alert function launches this restricted operation while the module is in
POWER DOWN mode. The module will not be registered to GSM network and
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only parts of AT commands can be available.
GHOST Mode
(Charge-only
mode)
GHOST mode means off and charging mode. In this mode, the module can not
be registered to GSM network and only limited AT commands can be
accessible, the following way will launch GHOST mode:
z From POWER DOWN mode: Connect charger to the module’s VCHG pin,
and battery is present while the module is power down.
z From Normal mode: Connect charger to the module’s VCHG pin, and
battery is present, then power down the module by “AT+CPOWD＝1”
Charge mode
during normal
Start charging while the module is in normal mode (including: SLEEP, IDLE,
TALK, GPRS IDLE and GPRS DATA)
operation
3.3 Power supply
The power supply of SIM548C GSM part is from a single voltage source of VBAT= 3.4V...4.5V.
In some case, the ripple in a transmitting burst may cause voltage drops when current consumption
rise 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 100µF, 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 (0.1 µF to 1µF) ceramic in parallel, which is
illustrated as following figure. The capacitors should put as close as possible to the module VBAT
pins.
Figure 2: Reference circuit of the VBAT input
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The circuit design of the power supply depends strongly on 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 4V, 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.
The single 3.6V Li-Ion cell battery type can be connected to the power supply of the module
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 for the module and damage it.
Figure 3: 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, C
capacitor (ESR=0.7Ω) and C
=1µF.
B
=100µF tantalum
A
Figure4: VBAT voltage drop during transmit burst
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3.3.1 Power supply pins on the board-to-board connector
Four VBAT pins of the board-to-board connector are dedicated to connect the supply voltage. The
VCHG pin serves as control signal for charging a Li-Ion battery. VRTC pin can be used to back
up the RTC.
3.3.2 Minimizing power losses
Please pay special attention to the supply power when you are designing your applications. Please
make sure that the input voltage will never drop below 3.4V even in a transmitting burst during
which the current consumption may rise up to 2A. If the power voltage drops below 3.4V, the
module may be switched off. So the impedance from extern power supply to module VBAT pins
should be as low as possible. When using a battery, you should also take the impedance of the
battery pack, the battery connector and PCB track on the host board into account. The PCB traces
from the VBAT pins of connector to the power source must be wide enough to ensure less voltage
drops occur in the transmitting burst mode.
3.3.3 Monitoring power supply
To monitor the supply voltage, you can use the “AT+CBC” command which include three
parameters: charging status, voltage percentage and voltage value (in mV). It returns charge state、
the battery voltage 1-100 percent of capacity and actual value measured at VBAT and GND.
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 down scenarios
3.4.1 Turn on the GSM part
The GSM part of SIM548C can be turned on by various ways, which are described in following
chapters:
z Via PWRKEY pin: starts normal operating mode;
z Via VCHG pin: starts GHOST modes;
z Via RTC interrupt: starts ALARM modes
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Note:
Only enter AT command through serial port after the module is power on and Unsolicited
Result Code “RDY” is received from serial port. However if autobauding is set, the serial port
will receive nothing. The AT command can be set after 2-3s from the GSM part is power on.You
can use AT+IPR=x;&W 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 when the GSM part is power on. Please refer to the
chapter AT+IPR in document [1].
3.4.1.1 Turn on the GSM part using the PWRKEY pin (Power on)
You can turn on the
GSM part of the module by driving the PWRKEY to a low level voltage for some
time and then release.This pin is pulled up to VBAT in the module. The maximum current that can
be drained from the PWRKEY pin is 0.4mA. The simple circuit illustrates as the following
figures.
Figure 5: Turn on
GSM part using driving circuit
Figure 6: Turn on GSM part using button
The power on scenarios illustrates as following figure.
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About 1.4s
STATUS
（OUTPUT）
Figure 7: Timing of turn on GSM part
When power on procedure complete, the GSM part of SIM548C will send out following result
code to indicate the module is ready to operate，and STATUS pin will drive to 2.8V and keep this
level when in work mode.
RDY
Only set baud rate that serial port can send out “RDY”, if set auto-baud rate, serial port will send
nothing.
3.4.1.2 Turn on the GSM part using the VCHG signal
As described in chapter 3.5, charger can be connected to the GSM part of the module’s VCHG pin
regardless of the module’s operating mode.
If the charger is connected to the module’s VCHG pin while the GSM part of the module is in
POWER DOWN mode, it will go into the GHOST mode (Off and charging). In this mode, the
module will not register to network, and only a few AT commands can work in this mode. For
detailed information please refers to chapter 3.5.4.
When the module is powered on using the VCHG signal, the GSM part of the module sends out
result code as following when fixed baud rate:
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RDY
GHOST MODE
+CFUN: 0
In GHOST mode, by driving the PWRKEY to a low level voltage for some time (Please refer to
the power on scenarios in 3.4.1.1), the GSM part of SIM548C will power up and go into charge
mode (charging in normal mode), all operation and AT commands can be available. In this case,
the GSM part of SIM548C will send out result code as following:
From GHOST MODE to NORMAL MODE
3.4.1.3 Turn on the GSM part using the RTC (Alarm mode)
Alarm mode is a power-on approach by using the RTC. The alert function of RTC makes the
GSM part of the module wake up while the module is power off. In alarm mode, the GSM part of
the module will not register to GSM network and the software protocol stack is close. Thus the
parts of AT commands related with SIM card and Protocol stack will not accessible, and the
others can be used as well as in normal mode.
Use the AT+CALARM command to set the alarm time. The RTC remains the alarm time if the
GSM part of the module is power down by “AT+CPOWD=1” or by PWRKEY pin. Once the
alarm time is expired and executed, the GSM part of the module will go into the Alarm mode. In
this case, the GSM part of the module will send out an Unsolicited Result Code (URC):
RDY
ALARM MODE
During alarm mode, use AT+CFUN command to query the status of software protocol stack; it
will return 0 which indicates that the protocol stack is closed. Then after 90s, the GSM part of the
module will power down automatically. However, during alarm mode, if the software protocol is
started by AT+CFUN=1 command, the process of automatic power down will not be available. In
ALARM mode, driving the PWRKEY to a low level voltage for a period will cause the GSM part
of the module to be powered down (Please refer to the power down scenario ).
The table follow briefly summarizes the AT commands that are used usually during alarm mode,
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for details of the instructions refer to document [1]:
Table 7: AT commands used in Alarm mode
AT command USE
AT+CALARM Set alarm time
AT+CCLK Set data and time of RTC
AT + CP O W D Power down
AT+CFUN Start or close the protocol stack
3.4.2 Turn off the GSM part
Following procedure can be used to turn off the GSM part of SIM548C:
z Normal power down procedure: Turn off the GSM part of SIM548C using the PWRKEY pin
z Normal power down procedure: Turn off the GSM part of SIM548C 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 the GSM part using the PWRKEY pin (Power down)
You can turn off the GSM part of SIM548C by driving the PWRKEY to a low level voltage for
some time. Please refer to the turn on circuit. The power down scenarios illustrate as figure 4.
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 STATUS pin, which
is a low level voltage in this mode.
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Figure 8: Timing of turn off GSM part
3.4.2.2 Turn off the GSM part using AT command
You can use an AT command “AT+CPOWD=1” to turn off the module. This command lets the
module to log off from the network and allows the GSM part 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 commands can’t be executed. The GSM part enters the POWER DOWN
mode, only the RTC is still active. POWER DOWN can also be indicated by STATUS 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 ≤ 3.5V, the
following URC will be presented:
UNDER-VOLTAGE WARNNING
If the voltage ≥ 4.5V, the following URC will be presented:
OVER-VOLTAGE WARNNING
The uncritical voltage range is 3.4V to 4.6V. If the voltage ≥ 4.6V or ≤ 3.4V, the module will
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be automatic shutdown soon.
If the voltage ≤ 3.4V, the following URC will be presented:
UNDER-VOLTAGE POWER DOWN
If the voltage ≥ 4.6V, 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 STATUS pin, which is a low level voltage in this mode.
3.4.2.4 Over-temperature or under-temperature automatic shutdown
The GSM part will constantly monitor the temperature of the module, if the temperature is equal
or higher than 85℃, the following URC will be presented:
+CMTE: 1
If the temperature ≤ -40℃, the following URC will be presented:
+CMTE:-1
The uncritical temperature range is -45℃ to 90℃. If the temperature ≥ 90℃ or ≤ -45℃, the
module will be automatic shutdown soon.
If the temperature ≥ 90℃, the following URC will be presented:
+CMTE:2
If the temperature ≤ -45℃, 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 DOWN mode, and only the RTC is still active. POWER DOWN can also be
indicated by STATUS pin, which is a low level voltage in this mode.
To monitor the temperature, you can use the “AT+CMTE” command to read the temperature when
the module is power on.
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For details please refer to document [1]
3.4.3 Restart the GSM part using the PWRKEY pin
You can restart the module by driving the PWRKEY to a low level voltage for some time, the
same as turning on the module using the PWRKEY pin. Before restarting the module, you need
delay at least 500ms from detecting the STATUS low level on. The restarting scenarios illustrates
as the following figure.
STATUS
VIL<0.6V
Figure 9: Timing of restart GSM part
3.5 Charging interface
The GSM part of the module has integrated a charging circuit for Li-Ion batteries charging control,
which make it very convenient for applications to manage their battery charging.
A common connection is shown in the following figure:
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Figure 10: Battery charger and pack
The TEMP_BAT function should be supported by the software in the module. It’s a customization
function. The R
is a NTC thermistor. We recommend to use NCP15XH103F03RC from
TEMP
MURATA. The impedance of the NTC thermistor is 10Kohm in 25℃. Please refer to the above
figure for the reference circuit.
3.5.1 Battery pack characteristics
The GSM part of the module has optimized the charging algorithm for the Li-Ion battery that
meets the characteristics listed below. To use the GSM part of the module’s charging algorithm
properly, it is recommended that the battery pack you integrated into your application is compliant
with these specifications. The battery pack compliant with these specifications is also important
for the AT command “AT+CBC” to monitor the voltage of battery, or the “AT+CBC” may return
incorrect battery capacity values.
z The maximum charging voltage of the Li-Ion battery pack is 4.2V and the capacity is
recommended to 580mAh. The capacity of battery packs down to 580mAh or more than
580mAh are allowed, too.
z The battery pack should have a protection circuit to avoid overcharging,overdischarging and
over-current. This circuit should be insensitive to pulsed current.
z On the GSM part of the module, the build-in power management chipset monitors the supply
voltage constantly. Once the Under-voltage is detected, the GSM part of the module will
power down automatically. Under-voltage thresholds are specific to the battery pack.
z The internal resistance of the battery and the protection circuit should be as low as possible.
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It is recommended that the battery internal resistance should not exceed 70mΩ and the
internal resistance include battery and protection circuit of battery pack should not exceed
130mΩ.
z The battery pack must be protected from reverse pole connection.
z The Li-Lon/Polymer battery charge protect parameter is required as following table
Table 8: recommended battery protect circuit parameter
Item Min. Typ. Max.
Over-charge protect threshold.(V) 4.25 4.3 4.35
Released Voltage from Over-charge(V) 4.1 4.2
Over-discharge protect threshold(V) 2.2 2.35
Released Voltage from Over-discharge(V) 2.35 2.4 2.45
3.5.2 Recommended battery pack
Following is the spec of recommended battery pack:
Table 9: Spec of recommended battery pack
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Product name & type SCUD Li-Ion, 3.7V, 800mAh
To obtain more information,
SCUD (FU JIAN) Electronic CO..LTD
Please contact :
Normal voltage 3.7V
Capacity Minimum 800mAh
Charge Voltage 4.200~4.23V
Max Charge Current 1.2C
Max Discharge Current 2C
Charge Method CC / CV (Constant Current / Constant Voltage)
Internal resistance ≤130mΩ
Over-charge protect threshold.(V) 4.28 ± 0.025
Released Voltage from Over-charge(V) 4.08 ± 0.05
Over-discharge protect threshold(V) 2.3± 0.1
Released Voltage from Over-discharge(V) 2.3± 0.1
3.5.3 Implemented charging technique
The GSM part of the module includes the function for battery charging. There are three pins in the
connector related with the battery charging function: VCHG, VBAT and TEMP_BAT pins. The
VCHG pin is driven by an external voltage, this pin can be used to detect a external charger
supply and provide most charging current through the GSM part of the module to battery when
charging is in fast charge state. The module VBAT pin give out charging current from the GSM
part of the module to external battery. TEMP_BAT pin is used for measuring the battery
temperature. Just let this pin open if battery temperature measuring is not your concern.
So it is very simple to implement charging technique, you need only connect the charger to the
VCHG pin and connect the battery to the VBAT pin.
When the GSM part of the module detected the charger supply and the battery are both present,
battery charging will happen. If there is no charger supply or no battery present, the charging will
not be enabled.
Normally, there are three main states in whole charging procedure.
z DDLO charge and UVLO charge;
z Fast charge;
z Trickle charge;
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DDLO charge and UVLO charge:
DDLO (deep discharge lock out) is the state of battery when its voltage under 2.4V. And UVLO
(under voltage lock out) means the battery voltage less than 3.2V and more than 2.4V. The battery
is not suitable for fast charge when its condition is DDLO or UVLO. The GSM part of the module
provides a small constant current to the battery when the battery is in DDLO or UVLO. In DDLO
charge, The GSM part of the module gives out 5mA current to the battery. And in UVLO charge,
The GSM part of the module provide about 30mA current to the battery.
DDLO charge terminated when the battery voltage reaches 2.4V. UVLO charge terminated when
the battery voltage is up to 3.2V. Both DDLO and UVLO charge are controlled by the GSM part
of the module hardware only.
Fast charge:
If there is a charger supply and battery present and the battery is not in DDLO and UVLO, the
GSM part of the module will enter fast charge state. Fast charge controlled by the software. Fast
charge delivers a strong and constant current (about 450mA) through VBAT pin to the battery
until battery voltage reach 4.2V.
Trickle charge:
After fast charging, the battery voltage is approach the whole battery capacity voltage, trick charge
begins .in this state, the GSM part of the module charge the battery under constant voltage.
3.5.4 Operating modes during charging
The battery can be charged during various operating mode. That means that when the GSM engine
is in Normal mode (SLEEP, IDLE, TALK, GPRS IDLE or GPRS DATA mode), charging can be
in progress while the GSM part of the module remains operational (In this case the voltage supply
should be sufficient). Here we name Charging in Normal mode as Charge mode.
If a charger is connected to the module’s VCHG pin and the battery is connected to the VBAT pin
while the GSM part of the module is in POWER DOWN mode, the GSM part of the module will
go into the GHOST mode (Off and charging). The following table gives the difference between
Charge mode and GHOST mode.
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Table 10: operating modes
How to activate mode Features
Connect charger to module’s VCHG pin
and connect battery to VBAT pin of
module while the GSM part of the module
is in Normal operating mode, including:
IDLE, TALK mode; SLEEP mode etc;
Charge Mode
Connect charger to module’s VCHG pin
while the GSM part of the module is in
POWER DOWN mode.
IMPORTANT: In GHOST mode not all
GHOST Mode
the software tasks are running.
z GSM remains operational and
registered GSM network while
charging is in progress;
z The serial interfaces are available in
IDLE, TALK mode, the AT
command set can be used fully in this
case;
In SLEEP mode, the serial interfaces are
not available, once the serial port is
connected and there is data in transfer.
Then the GSM part of the module will
exit the SLEEP mode.
z Battery can be charged when GSM
engine is not registered to GSM
network;
z Only a few AT commands is
available as listed below.
Note:
VBAT can not provide much more than 5mA current while the module is during the DDLO
charge state. In other words it is strongly recommended that VBAT should not be the main
power supply in the application subsystem while the module is during the DDLO charge state.
Table 11: AT Command usually used in GHOST mode
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AT command Function
AT+CALARM Set alarm time
AT+CCLK Set data and time of RTC
AT + CP O W D Power down
AT+CBC Indicated charge state and voltage
AT+CFUN Start or close the protocol
Set AT command“ AT+CFUN =1”,module
can be transferred from GHOST mode to
Charging in normal mode, In GHOST
mode , the default value is
3.5.5 Charger requirements
Following is the requirements of charger for the GSM part of the module.
- Simple transformer power plug
- Output voltage: 5.0V-5.25V
- Charging current limitation: 650mA
- A 10V peak voltage is allowed for maximum 1ms when charging current is switched off.
- A 1.6A peak current is allowed for maximum 1ms when charging current is switched on.
3.6 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 hardware interface signal can be
used to lead system to be in SLEEP mode (or slow clocking mode).
3.6.1 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 <fun>=0，1，4
z 0: minimum functionality;
z 1: full functionality (default);
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z 4: disable phone both transmit and receive RF circuits;
If the GSM part of the module has been set to minimum functionality by “AT+CFUN=0”, then the
RF function and SIM card function will be closed. In this case, the serial port is still accessible,
but all AT commands need RF function or SIM card function will not be accessible.
If the GSM part of the module has been set by “AT+CFUN=4”, the RF function will be closed,
the serial port is still active. In this case but all AT commands need RF function will not
accessible.
After the GSM part of the module 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].
3.6.2 SLEEP mode (slow clock mode)
We can control the GSM part of the module to enter or exit the SLEEP mode in customer
applications through DTR signal.
When DTR is in high level and there is no on air and hardware interrupt (such as GPIO interrupt
or data on serial port), the GSM part of the module will enter SLEEP mode automatically. In this
mode, the GSM part of the module can still receive paging or SMS from network.
In SLEEP mode, the serial port is not accessible.
Note: For some special software versions, 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.
3.6.3 Wake up the GSM part from SLEEP mode
When the GSM part of the module is SLEEP mode, the following method can wake up the module
z Enable DTR pin to wake up the GSM part of the module
If DTR pin is pull down to a low level，this signal will wake up the GSM part of the module
from power saving mode. The serial port will be active after DTR changed to low level for
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about 40ms.
z Receiving a voice or data call from network to wake up the GSM part of the module
z Receiveing a SMS from network to wake up the GSM part of the module
z RTC alarm expired to wake up the GSM part of the module
Note: DTR pin should be held low level during communicating between the module and DTE.
3.7 Summary of state transitions (except SLEEP mode)
Table 12: Summary of state transitions
Further
mode
Current
mode
POWER
DOWN
Normal
mode
POWER
DOWN
Normal
mode
Use
PWRKEY
AT+CPOWD
Connect charger
or use
PWRKEY pin
Ghost mode
(Charge-only
mode)
Connect charger
to VCHG and
connect battery to
VBAT
to VCHG and
connect battery to
VBAT, then
switch off module
by AT+CPOWD
or using
Charging in
normal
No direct
transition, but via
“Ghost mode” or
“Normal mode”
Connect charger
to VCHG pin of
module and
connect battery to
VBAT pin of
module
Alarm mode
Switch on from
POWER DOWN
mode by RTC
Set alarm by
“AT+CALARM
”, and then
switch off the
module. When
the timer expires,
the module turns
PWRKEY
on and enters
Alarm mode
Ghost
mode
(Charge-
only
mode)
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Disconnect
charger
No direct
transition, but
via “Charging
in normal”
mode
Turn on the
module using
PWRKEY OR
SET AT
Command
“AT+CFUN=1”
40
Set alarm by
“AT+CALARM
”, when the timer
expire, module
will enter Alarm
mode
SIM548C Hardware Design
Charging
in
normal
AT+CPOWD
→ “Ghost
mode”, then
disconnect
Disconnect
the charger
Switch off module
by AT+CPOWD
or using
PWRKEY
No direct
transition
charger
Alarm
mode
Use
PWRKEY pin
or wait
module
switch off
automatically
Use
AT+CFUN
No transition Use AT+CFUN
let module enter
Normal mode,
then connect the
charger to VCHG
pin of module
3.8 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 PIN 11 on the board-to-board connector. There
is a 10K resistance has been integrated in the GSM part of the module used for limiting current.
You need only a coin-cell battery or a super-cap to PIN 11 to backup power supply for RTC.
Note: The VRTC couldn’t be designed to a NC pin in your circuit. You should connect the
VRTC pin to a battery or a capacitor.
The following figures show various sample circuits for RTC backup.
Figure 11: RTC supply from non-chargeable battery
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Figure 12: RTC supply from rechargeable battery
Figure 13: RTC supply from capacitor
z Li-battery backup
Rechargeable Lithium coin cells such as the TC614 from Maxell, or the TS621 from Seiko, are
also small in size, but have higher capacity than the double layer capacitors resulting in longer
backup times.
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.
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Figure 14: Panasonic EECEMOE204A Charge Characteristic
Figure 15: Maxell TC614 Charge Characteristic
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Figure 16: Seiko TS621 Charge Characteristic
Note:
Gold-capacitance backup
Some suitable coin cells are the electric double layer capacitors available from Seiko (XC621),
or from Panasonic (EECEM0E204A). They have a small physical size (6.8mm diameter) and a
nominal capacity of 0.2F to 0.3F, giving hours of backup time.
3.9 GSM Serial interface
Table 13: Pin definition of the serial interfaces
Name Pin Function
DCD 25 Data carrier detection
DTR 27 Data terminal ready
RXD 29 Receive data
Serial port
TXD 31 Transmit data
RTS 33 Request to send
CTS 35 Clear to send
RI 37 Ring indicator
Debug port
DBG_RXD 36 Receive data
DBG_TXD 38 Transmit data
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The GSM part of the module provides two unbalanced asynchronous serial ports. One is the serial
port and another is the debug port. The GSM part 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 4800bps to 115200bps.
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 14: Logic levels of serial ports pins
Parameter Min Max Unit
VIL 0 0.9 V
VIH 2.1 3.3 V
VOL GND 0.2 V
VOH 2.8 3 V
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Figure 17:
Connection of the serial interfaces
Note: The RTS PIN must be connected to the GND in the customer circuit when only the TXD
and RXD are used in the Serial Port communication.
3.9.1 Function of serial port & debug port supporting
Serial port
z Seven lines on serial port.
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. Supports only basic mode of multiplexing so far.
z Serial port supports the communication rates as following:
300, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200 Default as 115200bps.
z Autobauding supports baud rates as following:
4800, 9600, 19200, 38400, 57600 and 115200bps.
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:
4800, 9600, 19200, 38400, 57600, 115200bps. 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
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paid to the following requirements:
Synchronization between DTE and DCE.
When DCE powers on with the autobauding enabled, it is recommended to wait 2 to 3 seconds
before sending the first AT character. After receiving the “OK” response, DTE and DCE are
correctly synchronized.
Restrictions on autobauding operation
z The serial port has to be operated at 8 data bits, no parity and 1 stop bit (factory setting).
z 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: You can use AT+IPR=x;&W 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 GSM part of
the module is power on.
Debug port
z Two lines on Debug port
z Only contains Data lines /TXD and /RXD
z Debug Port only used for debugging. It cannot be used for CSD call, FAX call. And the
Debug port can not use multiplexing function. It doesnot support autobauding function.;
z Debug port supports the communication rate as following:
9600, 19200, 38400, 57600, 115200bps(default)
3.9.2 Software upgrade and software debug
The TXD、RXD、DBG_TXD、DBG_RXD、GND must be connected to the IO connector when
user need to upgrade software and debug software, the TXD、RXD should be used for software
upgrade and the DBG_TXD、 DBG_RXD for software debugging. 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 the module is
upgrading software. Please refer to the following figures.
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Figure 18: Connection of software upgrade
Figure 19: Connection of software debug
The serial port and the debug port don’t support the RS232 level and it only supports the CMOS
level. Please refer to the table of Logic levels of serial ports pins 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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Figure20: RS232 level converter circuit
Note：For detail information about serial port application, please refer to document [12]
3.10 Audio interfaces
Table 15: Pin definition of the Audio interface
Name Pin Function
(AIN1/AOUT1)
(AIN2/AOUT2)
MIC1P 42 Microphone1 input +
MIC1N 44 Microphone1 input -
SPK1P 41 Audio1 output+
SPK1N 43 Audio1 output-
MIC2P 46 Microphone2 input +
MIC2N 48 Microphone2 input -
SPK2P 45 Audio2 output+
SPK2N 47 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
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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 multiplexers.
For each channels, you can use AT+CMIC to set the input gain level of microphone, use
AT+SIDET to set the side-tone level. In addition, you can also use AT+CLVL 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 the 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 you want
to adopt an amplifier circuit for audio, we recommend National company’s LM4890. Of course
you can select it according to your requirement.
Note
：
The GND and AGND should not be connected outside the module.
3.10.1 Speaker interface configuration
Figure 21: Speaker interface configuration
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Figure 22: Speaker interface with amplifier configuration
3.10.2 Microphone interfaces configuration
Figure 23: Microphone interface configuration
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3.10.3 Earphone interface configuration
Figure 24: Earphone interface configuration
3.10.4 Referenced electronic characteristic
Table 16: MIC Input Characteristics
Parameter Min Typ Max Unit
Working
1.2 1.5 2.0 V
Voltage
Working
200 500 uA
Current
External
1.2 2.2 k Ohms
Microphone
Load
Resistance
Table 17: SPK Output Characteristics
Parameter Min Typ Max Unit
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Normal
Output(SPK1)
Single
Ended
load
Resistance
Ref level 0.5477
27 32 Ohm
-12.04
Vpp
dBm
Differential
Auxiliary
Output(SPK2)
Ended
Differential
3.11 SIM interface
3.11.1 SIM card application
load
27 32
Resistance
Ref level 1.0954
-6.02
load
27 32
Resistance
Ref level 0.5477
-12.04
load
27 32
Resistance
Ref level 1.0954
-6.02
Ohm
Vpp
dBm
Ohm Single
Vpp
dBm
Ohm
Vpp
dBm
You 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 table18
Beside the SIM interface pin, there are also a SIM card holder in the module. The customer can
use either the SIM card holder in the module or the SIM interface pin.
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Table 18: Pin definition of SIM interface (board-to-board connector)
Pin Signal Description
17 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.
19 SIM_RST SIM Card Reset
21 SIM_DATA SIM Card data I/O
23 SIM_CLK SIM Card Clock
15 SIM_PRESENCE SIM Card Detection
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 SIM_PRESENCE pin is used for detecting the SIM card removal. You can use the AT
command “AT+CSDT” to set the SIMCARD configuration. For detail of this AT command,
please refer to document [1]:
You can select the 8-pins SIM card holder. The reference circuit about 8 pins SIM card holder
illustrates as following figure.
Figure 25: SIM interface reference circuit with 8-pin SIM card
If you don’t use the SIM card detection function, you can let the SIM_PRESENCE pin, connect to
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the GND. The reference circuit about 6 pins SIM card illustrate as following figure.
Figure 26: SIM interface reference circuit with 6-pin SIM card
3.11.2 Design considerations for SIM card holder
For 6-pin SIM card holder, we recommend to use Amphenol C707-10M006 512 2 .You can visit
http://www.amphenol.com
for more information about the holder.
Figure 27: Amphenol C707-10M006 512 2 SIM card holder
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Table 19: Pin definition (Amphenol SIM card holder)
Pin 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
C3
C5
C6
C7
SIM_RST SIM Card Reset.
SIM_CLK SIM Card Clock.
GND Connect to GND.
VPP Not connect.
SIM_DATA SIM Card data I/O.
For 8-pin SIM card holder, we recommend to use Molex 91228.You can visit
http://www.molex.com
for more information about the holder.
Figure 28: Molex 91228 SIM card holder
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Table 20: Pin definition (Molex SIM card holder)
Pin 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
C3
C4
C5
C6
C7
C8
SIM_RST SIM Card Reset.
SIM_CLK SIM Card Clock.
GND Connect to GND.
GND Connect to GND.
VPP Not connect.
SIM_DATA SIM Card data I/O.
SIM_PRESENCE Detect SIM Card Presence
3.12 LCD interface
The GSM part of the module provides a serial LCD display interface that supports serial
communication with LCD device. These are composite pins that can be used as GPIO ports or
LCD display interface according to your application. When use as LCD interface, the following
table is the pin description. LCD interface timing should be united with the LCD device.
Table
21: Pin definition of the LCD interface
Name Pin Function
DISP_DATA 28 Display data output
DISP_CLK 26 Display clock for LCD
DISP_CS 24 Display enable
DISP_D/C 30 Display data or command select
DISP_RST 32 LCD reset
Note: This function is not supported in the default firmware.There must be some special
firmware if you want. Please contact SIMCom for more details.
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3.13 ADC
The GSM part of the module provide two 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. User can use AT command “AT+RADC” to read the voltage
value added on ADC0 pin. For detail of this AT command, please refer to document [1].
Table
22: ADC specification
Min Typ Max Units
Voltage range 0 2.4 V
ADC Resolution 16 16 bits
ADC accuracy(1) 0.59 mV
Sampling rate 5 Sec
(1): ADC accuracy 12bits.
3.14 General purpose input & output(GPIO)
Table 23: Pin description of the GPIO interface
Pin Name Function
34
22
GPIO0 General Purpose Input/Output Port
GPIO1 General Purpose Input/Output Port
Note: This function is not supported in the default firmware. There must be special firmware if
you require. Please contact SIMCom for more details .
3.15 Behaviors of the RI line (serial port1 interface only)
Table 24: Behaviours of the RI line
State RI respond
Standby
HIGH
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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 hang up, change to HIGH
（4）Change to HIGH when SMS received.
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 120ms, then change to HIGH.
URC
Some URCs triggers 120ms low level on RI. For more details, please
refer to document [12]
If the module is used as caller, the RI on the board-to-board connector. However when it is used as
receiver, following is timing of RI.
Figure 29: The GSM part Services as Receiver
Figure 30: The GSM part Services as caller
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3.16 Network status indication
The NETLIGHT on the board-to-board connector can be used to drive a network status indication
LED lamp. The working state of this pin is listed in table;
Table 25: Working state of the NETLIGHT
State The GSM part of SIM548C function
Off The GSM part of the module is not running
64ms On/ 800ms Off The GSM part of the module does not find the network
64ms On/ 3000ms Off The GSM part of the module find the network
64ms On/ 300ms Off GPRS communication
We provide a reference circuitry for you, shown as the following figure:
Figure 31: Reference circuit of NETLIGHT
3.17 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
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shown as following figure:
Figure 32: Reference circuit of Buzzer
Table 26: Buzzer Output Characteristics
Parameter Min Typ Max Unit
Work i ng Volta g e 2.4 2.8 3.3 V
Working Current 2 mA
Load Resistance 1 k Ohms
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4 GPS application interface
A GPS receiver with high performance has been integrated to offer GPS full function, it
continuously tracks all satellites in view and provides accurate satellite position data. Otherwise,
the GPS part can run separately even while the GSM part of SIM548C has been deregistered form
the GSM network.
4.1 Theory of operation
The theory of operation is shown in the following figure:
Figure 33: Theory of operation
The Module’s GPS part is designed to use L1 Frequency (C/A Code) GPS receiver and performs
the entire GPS signal processing, from antenna input to serial position data output.
The processing steps involved are:
RF section
In the RF section the GPS signal detected by the antenna is amplified, filtered and converted to an
intermediate frequency (IF). An A/D converter converts the analogue intermediate frequency into
a digital IF signal.
GPS channels
The received digital IF signal bit stream is passed to the baseband section, where it is fed into the
correlators. The function of the correlators are to acquire and track the satellite signals. There are
12 channels used in parallel, with each correlator looking for a characteristic PRN code sequence
in the bit stream. Once the correlator has found a valid signal, pseudo range, carrier phase and
orbit information can be extracted from the GPS signal.
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GPS CORE
The on-board processor is running an algorithm that calculates the position, velocity and time.
This calculation is called navigation solution. Once the navigation solution is calculated, it can be
transformed into the desired coordinate system, e.g. Latitude/Altitude.
DATA OUT
The data of the navigation solution are available at the serial RS-232 interface.
4.2 Technical data
Power consumption
180mW with active antenna (continuous mode),
150mw with Passive antenna (continuous mode)
Push-to-Fix reduces power by as much as 98%
Note: The operation of Push-to-Fix mode please refer to document[2].
Protocols
SiRF binary/NMEA-0183
AI3/F (SIRF Interface) for AGPS
RTCM (for DGPS)
Position accuracy
Autonomous: < 10m
SBAS（WASS，EGNOS: < 5m）
Beacon DGPS: < 3m
Receiver
Tracking: L1, C/A code
Channels: 20
Update rate: Default 1 Hz
Tracking Sensitivity: -157 ± 2 dBm (refer to note)
Max. Altitude: <60.000 ft (18,000 m)
Max. velocity: <1.000 knots (515 m/s )
Protocol support: NMEA-0183, SiRF binary
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Acquisition rate
Standalone
Hotstart: < 1 seconds, open sky
Warmstart: < 38 seconds, open sky
Coldstart: < 42 seconds, open sky
AGPS
GSM: <1s, open sky
GSM: <24s, indoor
Note:
1) The receiver sensitivity above-mentioned is mostly related to antenna reference point, such as
the antenna type, the antenna amplifier, the customer application or the placement and the
applied reference setup and so on.
2) AGPS: This function needs more supporting form the mobile telecommunication network.
AGPS support, based on the AGPS firmware. Now the standard version of the firmware in the
module does not support AGPS.
4.3 Pin description
Table 27: Pin definition
Power Supply
PIN NAME I/O DESCRIPTION
GPS_VCC I GPS_VCC pins of the board-to-board
connector are dedicated to connect
the supply voltage. The power supply
Vmax= 5.0V
Vmin=3V
Vnorm=3.3V
for GPS whole part has to be a single
voltage source It must be able to
provide sufficient current of >150mA
in the procedure of tracking satellites
GPS_VRTC I Apply 3V dc for backup RTC &
SRAM. If unused, leave it open.
Vmax= 3.3V
Vmin=2.7V
Vnorm=3.0V
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GPS_VANT I The external DC power supply for an
active GPS antenna. It’s input voltage
depends on the type of chosen active
Imax=25mA
Vmax=5V
Vmin=2.85V
antenna, for the 5V type, it has to be
connected to 5V external power
supply; for the 3V type, it can be
connected to the GPS_VCC_RF pin
directly which provides 2.85V DC.
GPS_VCC_RF O The optional power supply for 3.0V
type active antenna.
Vmax=2.9V
Vmin=2.8V
Vnorm=2.85V
Imax=25mA
GND Ground, shared with GSM part
Dual serial interface
PIN NAME I/O DESCRIPTION DC CHARACTERISTICS
GPS_TXA O Serial data output for port A
GPS_RXA I Serial data input for port A
GPS_TXB O Serial data output for port B
GPS_RXB I Serial data input for port B
Control signals
PIN NAME I/O DESCRIPTION
GPS_BOOTSEL I For re-programming the Flash, it
must be set to High
GPS_M-RST I Reset pin, active low. If used, it
causes the module to reset; if not
used, leave it open .
VILmin=-0.3V
VILmax=0.84V
VIHmin=1.96V
VIHmax= 3.1
VOLmin=GND
VOLmax=0.7V
VOHmin=2.1V
VOHmax=2.8V
Note, if this pin is pulled
down by a GPIO, then the
GPIO must have the
capability of inputting
1.5mA current.
GPS_TimeMark O 1 PPS timemark output for
If not used, leave it open.
synchronizing to within 1
microsecond of GPS time.
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GPS_WAKEUP I It only be used to wakeup the system
from PTF mode. If not used, the user
must connect this pin to the ground
through a 0R resistor.
Table 28: Consolidated PIN Characteristics
PIN Default Direction
GPS_TXA O
GPS_RXA I
GPS_TXB O
GPS_RXB I
4.4 Turn on the GPS part
To turn on the GPS module, the GPS_VCC must be higher than 2.3V, and should be kept on for
220ms at least. The theory of turning on is shown in the following figure:
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Figure 34: Turn on the GPS module
4.5 The theory of the GPS R TC circuit
The RTC is very important for the GPS module, because the data kept in the SRAM is depended
on the VRTC. Please keep the VRTC on if you want to use the function of hotstart, warmstart, or
Push-To-Fix mode. There is a RTC LDO in our SIM548C module; it can provide 1.5V voltage to
the SRAM. The theory of RTC circuit is shown in the following figure:
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Figure 35: Theory of the GPS RTC circuit
4.6 The theory of the RESET Circuit
There is a RESET IC in the module’s GPS part. If the input of the reset IC is lower than 2.3V, the
“reset” pin will keep low; then the input voltage is higher than 2.3V, the RESET IC will output a
low level voltage for about 220mS as a reset signal. After that the reset output pin will be kept
high. So, if the user wants to reset the module’s GPS part, the GPS_M-RST should be pulled
down longer than 10ms, and then pull it up. The theory of the RESET Circuit is shown in the
figure:
Figure 36: Theory of the RESET circuit
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4.7 GPS operation modes
Table 29: GPS operation modes
Mode Function
Normal
operation
Power Down
mode
Push-to-Fix
mode (Refer to
Note)
The receiver is continuously running in Normal mode, as long as the operating
voltage Vcc is supplied. Position fixes are generated at the maximum update
rate. This enables the receiver a warm- and hotstart. However, the cold- and
warmstart times of receiver do not differ significantly under good visibility
conditions.
In this mode the user can cut off the GPS_VCC to save more power
consumption. But the VRTC must always be on. When the user resumes the
GPS_VCC, the receiver wakes up, a valid position can be computed in the
normal hot-start time.
In this mode the receiver will turn on every a given minutes (this period can be
set form 10 minutes to 2 hours by software) to perform a system update
consisting of position, time, ephemeris data refreshing and RTC calibration.
When the PTF mode is enabled, upon power on or a new PTF cycle, the
receiver will stay on full power until the good navigation solution is computed.
The stand-by state will follow for the remainder of the period. For example, if it
took 36 seconds to fix position and refresh ephemeris on the default period of
30 minutes, the receiver will sleep for the 29 minutes and 24 seconds. When the
application needs a position report, it can toggle the GPS_M-RST pin to wake
up the receiver. When the receiver wakes up, a valid position can be computed
in the normal hot-start time.
4.8 Serial interface of the GPS part
The GPS part of the module offers two serial interfaces, Allows for different protocols to operate
on each port.
For example：
Serial port A
z 2-wire serial interface
z Includes the GPS_RXA (receive) and TXA (transmit) lines
z Supported baud rate: 1200 -115200bps，but 4800 - 38400bps is a common rate range
z Protocol: Default NMEA ,4800bps
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z Default output message: GGA,GSA, GSV,RMC,VTG
z Update rate: Default 1Hz
z Datum WGS84 default (User configurable)
Serial port B
z 2-wire serial interface
z Includes the GPS_RXB(receive) and GPS_TXB (transmit) lines
z Supported baud rate: 1200－115200 bps
z Protocol: Default none
Notes:
1. Both interfaces are configured as 8 data bits, no parity and 1 stop bit..
2. The serial ports also can be configured to adapt to customer specific applications, such as for
DGPS, and so on. More detail please contact with SIMCom ltd.
3. We can also help the user to change the protocol and baud rate of the two serial ports by
different firmware. For more detail please contact SIMCom Ltd.
4.9 Start-up procedure
The start-up strategy of the module’s GPS part depends on the last position, current time and
ephemeris data, that the receiver has stored the external SRAM memory. There are three different
start-up procedures:
4.9.1 Coldstart
The coldstart takes place when the receiver has no knowledge of its last position or time. In this
case the GPS RTC has not been running and no valid ephemeris data or almanac data is available
(The receiver has never been navigating or no battery backup memory available).
4.9.2 Warmstart
This start-up procedure is performed whenever the receiver is able to use the valid almanac data,
and has not in an important manner moved since the last valid position calculation. This procedure
starts if the receiver has been shut off for more than 2 hours, but the last position, time and
almanac are still acknowledged. This procedure is able to announce the current visible satellites in
advance. However, since ephemeris data are not available or cannot longer be used, the receiver
has to wait for the ephemeris broadcast to complete.
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4.9.3 Hotstart
Hotstart is performed whenever the receiver still has access to valid ephemeris data and exact time.
This procedure starts if the receiver has been shut off for less than 2 hours and the GPS RTC has
been running during that time. Furthermore, during the previous session, the receiver must have
been navigating (to allow it to decode and store ephemeris data). In Hotstart, the receiver can
announce in advance the currently visible satellites, and is therefore able to quickly obtain and
track the signal. Due to the fact that ephemeris is already known, there is no need to wait for the
ephemeris broadcast to complete.
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5 Antenna interface
5.1 GSM Antenna
The RF interface has an impedance of 50Ω. To suit the physical design of individual applications
the module offers alternatives:
z Recommended approach: antenna connector on the component side of the PCB
z Antenna pad and grounding plane placed on the bottom side.
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 requirement:
z GSM850/GSM900<0.5dB
z DCS1800/PCS1900<1.0dB
5.1.1 GSM Antenna connector
The module use MURATA’s MM9329-2700 RA1 RF connector on the module side, we
recommend user use MURATA’s MXTK92XXXXX as matching connector on the application side.
Please refer to appendix for detail info about MURATA’s MXTK92XXXXX.
5.1.2 GSM Antenna pad
The antenna can be soldered to the pad, or attached via contact springs. To help you to ground the
antenna, The module comes with a grounding plane located close to the antenna pad. The antenna
pad of the module is shown as the following figure:
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Figure 37: RF connector and RF pad
The GSM part of SIM548C material properties:
PCB Material: FR4
Antenna pad: Gold plated pad
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5.1.3 Module RF output power
Table 30: The GSM part 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
5.1.4 Module RF receive sensitivity
Table 31: Conducted RF receive sensitivity of the GSM part
Frequency Receive sensitivity
GSM850 < -106dBm
EGSM900 < -106dBm
DCS1800 < -106dBm
PCS1900 < -106dBm
5.1.5 Module operating frequencies
Table 32: The GSM part operating frequencies
Frequency Receive Transmit
GSM850
EGSM900
DCS1800
PCS1900
869 ～ 894MHz 824 ～ 849MHz
925 ～ 960MHz 880 ～ 915MHz
1805 ～ 1880MHz 1710 ～ 1785MHz
1930 ～ 1990MHz 1850 ～ 1910MHz
5.2 GPS Antenna
5.2.1 GPS Antenna Connection
As same as the GSM antenna interface, the module also offer two alternative methods for
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customer to install the GPS antenna.
The first method, and which is our recommended method, is installing GPS antenna via a proper
Microwave Coaxial Cable and connect to the antenna connector of the module provided. About
the connector’s type and the matched Microwave Coaxial Cable, please refer to the section 5.1.1.
The second method of installing the GPS antenna is soldering the GPS antenna on the GPS
antenna pad of the module provided. The antenna pad’s structure is similar to the GSM Antenna
pad which is refered in section 5.1.2. The GND pad, which close to the GPS antenna pad, is
provided to customer for soldering the Microwave coaxial cable’s outer conductor with the
module’s GND. The location of the GPS Antenna Connector and GPS antenna pad can be found
in the following figure.
Figure 38: RF connector
5.2.2 GPS Antenna Choice Consideration
To obtain excellent GPS reception performance, a good antenna will always be required. The
antenna is the most critical item for successful GPS reception in a weak signal environment.
Proper choice and placement of the antenna will ensure that satellites at all elevations can be seen,
and therefore, accurate fix measurements are obtained. Most customers contract with antenna
design houses to properly measure the radiation pattern of the final mounted configuration in a
plastic housing with associated components near the antenna. Linear antennas are becoming more
popular, and the gain is reasonable, since a smaller ground plane can be used. Chose a linear
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antenna with a reasonably uniform hemispherical gain pattern of >-4dBi. Use of an antenna with
lower gain than this will give less than desirable results. Please note that a RHCP antenna with a
gain of -3dBic, equates to a linear polarized antenna of -0dBi. Proper ground plane sizing is a
critical consideration for small GPS antennas. Proper placement of the GPS antenna should always
be the FIRST consideration in integrating the GPS Module.
If the customer’s design will allow for a ceramic RHCP patch antenna with an appropriately sized
ground plane, and the patch is normally oriented towards the sky, then that particular solution
usually works the best. Please note that if the patch antenna ground plane is less than 60x60mm,
then compromises to the beam width and gain pattern could result. Usually the gain becomes very
directional, and looses several dB of performance. Since results can vary, measuring the antenna
radiation pattern in the final housing in an appropriate anechoic chamber will be required.
Some customers do not have the size availability to implement a patch antenna approach. In that
instance, use of a Linear Polarized (LP) antenna is the next best alternative. There are new ceramic
LP antennas on the market that exhibit reasonable gain characteristics once properly mounted in
the housing, and when mated to an appropriate sized ground. That is the key point to consider here.
“When mated to an appropriate sized ground”.
Usually, the ground plane requirements are smaller for a LP antenna when compared to a patch,
but once again, proper testing in an anechoic chamber is a mandatory requirement. These ceramic
elements will need to be located near the end of the ground plane, and will require several mm of
clearance between the closest component.
It is important to note that use of a LP antenna will result in a minimum of 3dB of gain loss when
compared to a RHCP antenna at a defined elevation. This is due to the right hand gain rule of
antenna propagation.
Use of PIFA antenna is another LP possibility, but the PIFA usually exhibits a considerable
amount of gain nulls, or “holes” in the radiation pattern. This will be undesirable for obtaining a
low circular error probability (CEP), since the antenna may not allow the receiver to capture the
desired satellite at the ideal orientation due to these noted gain nulls.
Once again, careful testing in an appropriate anechoic chamber is required.
If the customer’s design is for automotive applications, then an active antenna can be used and
located on top of the car in order for guarantee the best signal quality.
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Here are two GPS antenna manufacturers be recommended, you can visit their websites for details,
http://www.inpaq.com.tw
should base on the designing product and other conditions.
For detailed Antenna designing consideration, please refer to related antenna vendor’s design
recommendation. The antenna vendor will offer further technical support and tune their antenna
characteristic to achieve successful GPS reception performance depends on the customer’s design.
and http://www.passivecomponent.com. But the GPS antenna choice
6 Electrical, reliability and radio characteristics
6.1 Absolute maximum ratings
Absolute maximum rating for power supply and voltage on digital and analog pins of SIM548C
are listed in table 33 and table 34.
Table 33: Absolute maximum ratings (GSM part)
Parameter Min Max Unit
Peak current of power supply 0 3.0 A
RMS current of power supply (during one TDMA- frame) 0 0.7 A
Voltage at digital pins -0.3 3.3 V
Voltage at analog pins -0.3 3.0 V
Voltage at digit/analog pins in POWER DOWN mode -0.25 0.25 V
Table 34: Absolute maximum ratings (GPS part)
Parameter Min Max Unit
Voltage at GPS_VCC -0.3 5 V
Current at GPS_VCC_RF 25 mA
6.2 Operating temperatures
The operating temperature is listed in table35:
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Table 35: 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 module does work, but deviations from the GSM specification may occur, For example, the
frequency error or the phase error will be large.
6.3 Power supply rating
Table 36: Power supply rating (GSM part)
Parameter Description Conditions Min Typ Max Unit
VBAT
IVBAT
Supply voltage Voltage must stay within the
min/max values, including
voltage drop, ripple, and spikes.
Voltage drop
during transmit
Normal condition, power
control level for Pout max
burst
Voltage ripple Normal condition, power
control level for Pout max
@ f<200kHz
@ f>200kHz
Average supply
current)
POWER DOWN mode
SLEEP mode
( BS-PA-MFRMS=5 )
IDLE mode (Not connect
console）
3.4 4.0 4.5 V
400 mV
50
mV
2
35
2.5
uA
mA
mA
EGSM 900
DCS 1800/ PCS 1900
IDLE mode（connect console）
EGSM 900
DCS 1800/ PCS 1900
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TALK mode
EGSM 900
DCS 1800/ PCS 1900
DATA mode, GPRS(3 Rx,2Tx)
EGSM 900
DCS 1800/ PCS 1900
DATA mode, GPRS(4 Rx,1Tx)
EGSM 900
DCS 1800/ PCS 1900
Peak supply
Power control level 2 3.1 A
current (during
transmission
slot every 4.6ms)
Table 37: Power supply rating (GPS part)
260
200
470
340
275
220
mA
mA
mA
Parameter Description Conditions Min Typ Max Unit
GPS_VCC Supply voltage 3.0 3.3 5 V
IGPS_VCC Average supply
current
Continuous mode (with antenna
feeding on GPS_VCC_RF)
65 110 mA
Note: Basing on current standard GSW3 soft version, the power saving mode of GPS part is not
available, that results 65 mA IGPS_VCC remained while the GPS receiver is running in normal
mode.
6.4 Current consumption
6.4.1 The current consumption of the GSM part.
Table 38: Current consumption (GSM part)
Voice Call
EGSM 900/EGSM 850 @power level #5 <350mA,Typical 260mA
@power level #10,Typical 130mA
@power level #19,Typical 86mA
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DCS 1800/ PCS 1900 @power level #0 <300mA,Typical 200mA
@power level #10,Typical 87mA
@power level #15,Typical 80mA
GPRS Data
DATA mode, GPRS ( 1 Rx,1 Tx )CLASS 8
EGSM 900/ EGSM 850 @power level #5 <350mA,Typical 260mA
@power level #10,Typical 125mA
@power level #19,Typical 84mA
DCS 1800/ PCS 1900 @power level #0 <300mA,Typical 200mA
@power level #10,Typical 83mA
@power level #15,Typical 76mA
DATA mode, GPRS ( 3 Rx, 2 Tx )CLASS 10
EGSM 900/EGSM 850 @power level #5 <550mA,Typical 470mA
@power level #10,Typical 225mA
@power level #19,Typical 142mA
DCS 1800/ PCS 1900 @power level #0 <450mA,Typical 340mA
@power level #10,Typical 140mA
@power level #15,Typical 127mA
DATA mode, GPRS ( 4 Rx,1 Tx )CLASS 8
EGSM 900/EGSM 850 @power level #5 <350mA,Typical 270mA
@power level #10,Typical 160mA
@power level #19,Typical 120mA
DCS 1800/ PCS 1900 @power level #0 <300mA,Typical 220mA
@power level #10,Typical 120mA
@power level #15,Typical 113mA
Class 10 is default set when the module work at data translation mode, the module can also work
at class 8 set by AT command.
6.4.2 The current consumption of the GPS part
To save more current consumption, we suggest the user to design their system in one of the two
modes: 1. Power Down mode; 2.Push-To-Fix mode
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6.4.2.1 Power down Mode
The circuit of this mode is shown in the figure:
Figure 39: Power Down mode
When the user wants to save more current consumption of the GPS part, he can pull down the
POWER_CTRL of the MCU to stop the LDO outputting. And this operation will cut off the
power of the GPS part. Note that the GPS_VRTC must be kept on.
6.4.2.2 Push-To-Fix mode
The circuit of this mode is shown in figure 40.
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Figure 40: Push-To-Fix mode
The user can also save power by sending the “Push-To-Fix” command to the GPS part of the
module.
The Push-to-Fix mode puts the receiver into a background duty cycle mode that provides a
periodic refresh of position, GPS time, ephemeris, and RTC calibration every 10 seconds to 2
hours. Typical PTF operation is illustrated in Figure 39.
The PTF period is 30 minutes by default but can be anywhere between 10 seconds and 2 hours.
When the PTF mode is enabled, upon power on or a new PTF cycle, the receiver will stay on full
power until the good navigation solution is computed. The stand-by state will follow for the
remainder of the period. If it took 36 seconds to fix position and refresh ephemeris on the default
period of 30 minutes, the receiver will sleep for the 29 minutes and 24 seconds. When the
application needs a position report, it can toggle the GPS_M-RST pin to wake up the receiver.
When the receiver wakes up, it can produce a valid position in the normal hot-start time.
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Power consumption in the PTF mode
Again, a typical setting of 1800 seconds PTF interval is considered.
Assuming it takes 8 seconds to compute a good position since the start of a cycle, the average
current and power consumption of each typical cycle is：
Iavg = (65 mA * 8160 ms + 1 mA * 1791840 ms) / 1800 seconds = 1.290 mA
Pavg = 3.3 V * 1.290 mA = 4.257 mW
Figure 41: Power consumption in the PTF mode
Note:
1. When the user wants to use Power Down mode or Push-To-Fix mode, the RTC battery must
be 2.5V+.If the RTC battery level is lower than 2.5V, the module will not go into PTF mode.
2. Push-To-Fix mode is only available in protocol of :SiRF binary, please refer to the document
[2].
6.5 Electrostatic 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 SIM548C module.
The measured values of SIM548C are shown as the following table:
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Table 39: The ESD endure statue measured table (Temperature: 25 , Humidity: 45% )℃
Part Contact discharge Air discharge
VBAT,GND ±6KV ±10KV
DTR, RXD, TXD, RTS,
DISP_DATA, DISP_CLK
Antenna port ±4KV ±8KV
Other port ±4KV ±8KV
±4KV ±10KV
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7 Mechanics
This chapter describes the mechanical dimensions of SIM548C.
7.1 Mechanical dimensions
Following shows the Mechanical dimensions of SIM548C.
Figure 42: Mechanical dimensions of module（Unit: mm）
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Figure 43: Mount the module（Unit: mm）
Figure 44: Mechanical dimensions of module PCB decal（Unit: mm）
7.2 Mounting the module onto the application platform
Use the connector ASTRON1491060-09T-R and four pads to fix the SIM548C onto customer
platform.
7.3 Board-to-board connector
We recommend ASTRON Company’s1491060-09T-R and 1590060-09T-R as the board-to-board
connector. These high density SMT connectors are designed for parallel PCB-to-PCB
applications.
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7.3.1 Mechanical dimensions of the ASTRON 1590060-09T-R
Figure 45: ASTRON1590060-09T-R Board to Board connector
Figure 46: ASTRON Board to Board connector physical photo
Note：The connector ASTRON ASTRON1491060-09T-R is used in pin side (548C module)
and 1590060-09T-R is used in socket side (user side).
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7.3.2 Adapter cabling
Figure 47: MM9329-2700B
Figure 48: RF connector MXTK
For more information about the connector, please visit http://www.murata.com/
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APPENDIX A: PIN assignment of board-to-board connector
Table 40: Pin assignment
PIN NO. PIN NAME I/O
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49
51
53
55
57
59
GND
GND
GND
GND
ADC0
VRTC
PWRKEY
SIM_PRESENCE
SIM_VDD
SIM_RST
SIM_DATA
SIM_CLK
DCD
DTR
RXD
TXD
RTS
CTS
RI
AGND
SPK1P
SPK1N
SPK2P
SPK2N
GPS_M-RST
GPS_TXA
GPS_RXA
GPS_TXB
GPS_RXB
GPS_VRTC
2
4
6
8
I 10
I/O 12
I 14
I 16
O 18
O 20
I/O 22
O 24
O 26
I 28
I 30
O 32
I 34
O 36
O 38
40
O 42
O 44
O 46
O 48
I 50
O 52
I 54
O 56
I 58
I 60
PIN NO. PIN NAME I/O
VBAT
VBAT
VBAT
VBAT
VCHG
VCHG
TEMP_BAT
NETLIGHT
BUZZER
STATUS
GPIO1
DISP_CS
DISP_CLK
DISP_DATA
DISP_D/C
DISP_RST
GPIO0
DBG_RXD
DBG_TXD
AGND
MIC1P
MIC1N
MIC2P
MIC2N
GPS_BOOTSEL
GPS_TIMEMAR
I
I
I
I
I
I
I
O
O
O
I/O
O
O
I/O
O
O
I/O
I
O
I
I
I
I
I
O
K
GPS_WAKEUP
GPS_VCC_RF
GPS_VANT
GPS_VCC
I
O
I
I
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The following figure is a top-view of SIM548C module. With the indication of Pin 1, 2, 59 and 60.
Figure 49: physical SIM548C
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APPENDIX B: Reference Circuit with external MCU (GPS standalone application)
Figure 50: Reference Circuit with external MCU (standalone application for example)
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APPENDIX C: Reference Diagram with external MCU (AGPS application)
The next Figure shows the connection for AGPS application ,DISP_DATA pin is used for TX and
DISP_D/C for RX. For details please refer to AGPS application note document.
Figure 51: AGPS connection
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Contact us:
Shanghai SIMCom Wireless Solutions Ltd.
Add: SIM Technology Building, No. 700, Yishan Road, Shanghai,P. R. China 200233
Tel: +86 21 5427 8900
Fax: +86 21 5427 6035
URL: www.sim.com/wm/
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