Gemalto M2M XT55 Updated Usaer Manual
XT55/56 Hardware Interface Description
p
Confidential / Preliminary
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tion
XT55/56
Siemens Cellular Engine
Version: 02.96
DocID: XT55/56_hd_v02.96
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Hardware Interface Descri
XT55/56 Hardware Interface Description
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Confidential / Preliminary
Document Name:
Version:
Date:
DocId:
Status:
XT55/56 Hardware Interface Description
02.96
August 18, 2005
XT55/56_hd_v02.96
Confidential / Preliminary
General Notes
Product is deemed accepted by recipient and is provided without interface to recipient’s products. The
documentation and/or product are provided for testing, evaluation, integration and information
purposes. The documentation and/or product are provided on an “as is” basis only and may contain
deficiencies or inadequacies. The documentation and/or product are provided without warranty of any
kind, express or implied. To the maximum extent permitted by applicable law, Siemens further
disclaims all warranties, including without limitation any implied warranties of merchantability,
completeness, fitness for a particular purpose and non-infringement of third-party rights. The entire
risk arising out of the use or performance of the product and documentation remains with recipient.
This product is not intended for use in life support appliances, devices or systems where a malfunction
of the product can reasonably be expected to result in personal injury. Applications incorporating the
described product must be designed to be in accordance with the technical specifications provided in
these guidelines. Failure to comply with any of the required procedures can result in malfunctions or
serious discrepancies in results. Furthermore, all safety instructions regarding the use of mobile
technical systems, including GSM products, which also apply to cellular phones must be followed.
Siemens or its suppliers shall, regardless of any legal theory upon which the claim is based, not be
liable for any consequential, incidental, direct, indirect, punitive or other damages whatsoever
(including, without limitation, damages for loss of business profits, business interruption, loss of
business information or data, or other pecuniary loss) arising out the use of or inability to use the
documentation and/or product, even if Siemens has been advised of the possibility of such damages.
The foregoing limitations of liability shall not apply in case of mandatory liability, e.g. under the
German Product Liability Act, in case of intent, gross negligence, injury of life, body or health, or
breach of a condition which goes to the root of the contract. However, claims for damages arising from
a breach of a condition, which goes to the root of the contract, shall be limited to the foreseeable
damage, which is intrinsic to the contract, unless caused by intent or gross negligence or based on
liability for injury of life, body or health. The above provision does not imply a change on the burden of
proof to the detriment of the recipient. Subject to change without notice at any time. The interpretation
of this general note shall be governed and construed according to German law without reference to
any other substantive law.
Copyright
Transmittal, reproduction, dissemination and/or editing of this document as well as utilization of its
contents and communication thereof to others without express authorization are prohibited. Offenders
will be held liable for payment of damages. All rights created by patent grant or registration of a utility
model or design patent are reserved.
Copyright © Siemens AG 2005
Trademark notices
MS Windows® is a registered trademark of Microsoft Corporation.
SiRFDemo Software and SiRFstar are registered trademarks of SiRF Technology Inc., San Jose,
California.
Section 4.2, 4.3.1, 4.8 and 9 used with the permission of SiRF Technology, Inc., San Jose, California
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Contents
0 Document History .........................................................................................................8
1 Introduction .................................................................................................................11
1.1 Supported Software and Hardware Releases .....................................................11
1.2 Related Documents .............................................................................................12
1.3 Terms and Abbreviations.....................................................................................13
1.4 Type Approval......................................................................................................17
1.5 Safety Precautions...............................................................................................19
2 Product Concept .........................................................................................................21
2.1 XT55/56 Key Features at a Glance .....................................................................22
2.2 Circuit Concept ....................................................................................................25
3 GSM Application Interface .........................................................................................27
3.1 GSM/GPRS Operating Modes.............................................................................27
3.2 Power Supply.......................................................................................................29
3.2.1 Power Supply Pins on the Board-to-Board Connector...........................29
3.2.2 Minimizing Power Losses ......................................................................30
3.2.3 Monitoring Power Supply ....................................................................... 30
3.3 Power Up / Down Scenarios................................................................................31
3.3.1 Turn on the GSM Part of XT55/56 .........................................................31
3.3.1.1 Turn on the GSM Part of XT55/56 Using the Ignition Line GSM_IGT
(Power on) .............................................................................................32
3.3.1.2 Timing of the Ignition Process................................................................33
3.3.1.3 Turn on the GSM Part of XT55/56 Using the GSM_POWER Signal .....34
3.3.1.4 Turn on the GSM Part of XT55/56 Using the RTC (Alarm Mode)..........34
3.3.2 Turn off the GSM Part of XT55/56 .........................................................35
3.3.2.1 Turn off GSM Part of the XT55/56 Module Using AT^SMSO ................36
3.3.2.2 Emergency Shutdown Using GSM_EMERGOFF Pin............................37
3.3.3 Automatic Shutdown .............................................................................. 38
3.3.3.1 Temperature Dependent Shutdown.......................................................38
3.3.3.2 Temperature Control during Emergency Call ........................................39
3.3.3.3 Undervoltage Shutdown if Battery NTC is Present ................................39
3.3.3.4 Undervoltage Shutdown if no Battery NTC is Present ...........................40
3.3.3.5 Overvoltage Shutdown...........................................................................40
3.4 Automatic GPRS Multislot Class Change............................................................41
3.5 Charging Control of the GSM Part.......................................................................42
3.5.1 Battery Pack Characteristics..................................................................44
3.5.2 Recommended Battery Pack Specification............................................45
3.5.3 Implemented Charging Technique.........................................................46
3.5.4 Operating Modes during Charging.........................................................48
3.5.5 Charger Requirements...........................................................................49
3.6 Power Saving.......................................................................................................50
3.6.1 No Power Saving (AT+CFUN=1) ...........................................................50
3.6.2 NON-CYCLIC SLEEP Mode (AT+CFUN=0)..........................................50
3.6.3 CYCLIC SLEEP Mode (AT+CFUN=5, 6, 7, 8) .......................................51
3.6.4 CYCLIC SLEEP Mode AT+CFUN=9 .....................................................51
3.6.5 Timing of the GSM_CTS Signal in CYCLIC SLEEP Modes ..................51
Wake up XT55/56 from SLEEP Mode .................................................................53
3.6.5.1 Wake-up via /RTS0 and RTS1 (if AT+CFUN=0 or AT+CFUN=9)..........54
3.7 Summary of State Transitions (Except SLEEP Mode).........................................55
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3.8 RTC Backup for GSM Part of XT55/56................................................................56
3.9 Serial Interfaces of the XT55/56 GSM Part .........................................................57
3.9.1 Features Supported on the first Serial Interface of GSM Part (ASC0)...57
3.9.2 Features Supported on the second Serial Interface of GSM Part (ASC1)
...............................................................................................................58
3.9.3 ASC0 and ASC1 Configuration..............................................................58
3.10 Audio Interfaces...................................................................................................59
3.10.1 Microphone Circuit.................................................................................60
3.10.2 Speech Processing................................................................................61
3.10.3 DAI Timing .............................................................................................61
3.11 SIM Interface .......................................................................................................63
3.11.1 Requirements for Using the GSM_CCIN Pin .........................................64
3.11.2 Design Considerations for SIM Card Holder..........................................65
3.12 Control Signals ....................................................................................................66
3.12.1 Inputs .....................................................................................................66
3.12.2 Outputs ..................................................................................................67
3.12.2.1 Synchronization Signal ..........................................................................67
3.12.2.2 Using the GSM_SYNC Pin to Control a Status LED..............................68
3.12.3 Behavior of the GSM_RING0 Line (ASC0 Interface only) .....................70
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4 GPS Application Interface .......................................................................................... 71
4.1 Theory of Operation.............................................................................................71
4.2 Technical Data.....................................................................................................72
4.3 GPS Operating Modes.........................................................................................73
4.3.1 Trickle Power Mode ...............................................................................74
4.3.2 Comparison of Trickle Power and Push-to-Fix Mode ............................75
4.4 Power Supply of the XT55/56 GPS Part..............................................................76
4.5 General Purpose Input/Output (GPIO) ................................................................76
4.6 Serial Interfaces of the XT55/56 GPS Part ..........................................................77
4.7 GPS Control Signals............................................................................................77
4.8 Receiver Architecture ..........................................................................................78
4.9 Operation Procedure ...........................................................................................79
4.10 Start-up Procedures.............................................................................................80
4.10.1 Coldstart.................................................................................................80
4.10.2 Warmstart ..............................................................................................80
4.10.3 Hotstart ..................................................................................................80
5 GSM and GPS Antenna Interfaces.............................................................................81
5.1 GSM Antenna Installation ....................................................................................81
5.1.1 GSM antenna Connector .......................................................................81
5.1.2 GSM Antenna Pad ................................................................................. 83
5.2 Installing the GPS Antenna..................................................................................83
5.3 Hirose Antenna Connector ..................................................................................84
6 Electrical, Reliability and Radio Characteristics......................................................88
6.1 Absolute Maximum Ratings .................................................................................88
6.2 Operating Temperatures......................................................................................88
6.3 Pin Description.....................................................................................................90
6.4 Power Supply Ratings .........................................................................................96
6.4.1 Current Consumption during GSM Transmit Burst ................................98
6.5 Electrical Characteristics of the Voiceband Part................................................103
6.5.1 Setting Audio Parameters by AT Commands ......................................103
6.5.2 Audio Programming Model ..................................................................104
6.5.3 Characteristics of Audio Modes ...........................................................105
6.5.4 Voiceband Receive Path......................................................................106
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6.5.5 Voiceband Transmit Path.....................................................................107
6.6 Air Interface of the XT55/56 GSM Part ..............................................................108
6.7 Electrostatic Discharge ......................................................................................109
6.8 Reliability Characteristics...................................................................................110
7 Mechanics..................................................................................................................111
7.1 Mechanical Dimensions of XT55/56 ..................................................................111
7.2 Mounting XT55/56 onto the Application Platform ..............................................113
7.3 Board-to-Board Connector.................................................................................115
8 Reference Approval ..................................................................................................117
8.1 Reference Equipment for Type Approval...........................................................117
8.2 Compliance with FCC Rules and Regulations (XT55 only) ...............................118
8.3 Compliance with FCC Rules and Regulations (XT56 only) ...............................119
9 Example Applications............................................................................................... 120
10 List of Parts and Accessories.................................................................................. 124
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Figures
Figure 1: Product label placed on XT55/56 module ............................................................... 11
Figure 2: Block diagram of serial interface concept ...............................................................26
Figure 3: Power supply limits during transmit burst................................................................ 30
Figure 4: Power-on by ignition signal ..................................................................................... 32
Figure 5: Timing of power-on process if GSM_VDDLP is not used .......................................33
Figure 6: Timing of power-on process if GSM_VDDLP is fed from external source ..............34
Figure 7: Deactivating GSM engine by GSM_EMERGOFF signal.........................................37
Figure 8: Schematic of approved charging transistor, trickle charging and ESD protection ..42
Figure 9: Battery pack circuit diagram....................................................................................44
Figure 10: Charging process .................................................................................................. 47
Figure 11: Timing of CTS signal (example for a 2.12 s paging cycle).................................... 52
Figure 12: Beginning of power saving if CFUN=5 or 7........................................................... 52
Figure 13: RTC supply from capacitor.................................................................................... 56
Figure 14: RTC supply from rechargeable battery ................................................................. 56
Figure 15: RTC supply from non-chargeable battery ............................................................. 56
Figure 16: Audio block diagram.............................................................................................. 59
Figure 17: Schematic of microphone inputs ...........................................................................60
Figure 18: DAI timing on transmit path................................................................................... 62
Figure 19: DAI timing on receive path ....................................................................................62
Figure 20: SIM card holder of DSB45 Support Box................................................................ 65
Figure 21: Pin numbers of Molex SIM card holder on DSB45 Support Box........................... 65
Figure 22: GSM_SYNC signal during transmit burst.............................................................. 67
Figure 23: LED Circuit (Example)........................................................................................... 69
Figure 24: Incoming voice call................................................................................................70
Figure 25: URC transmission ................................................................................................. 70
Figure 26: Theory of operation ............................................................................................... 71
Figure 27: Example for current in Trickle Power mode .......................................................... 74
Figure 28: Comparing typical current in Trickle Power and Push-to-Fix mode ...................... 75
Figure 29: Example of LED circuit.......................................................................................... 78
Figure 30: Receiver architecture of the GPS receiver............................................................ 78
Figure 31: U.FL-R-SMT connector .........................................................................................81
Figure 32: Antenna pad and GND plane ................................................................................81
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Figure 33: Never use antenna connector and antenna pad at the same time .......................82
Figure 34: Restricted area around antenna pad..................................................................... 82
Figure 35: GPS antenna connector (U.FL-R-SMT connector) ............................................... 83
Figure 36: Mechanical dimensions of U.FL-R-SMT connector............................................... 84
Figure 37: U.FL-R-SMT connector with U.FL-LP-040 plug .................................................... 85
Figure 38: U.FL-R-SMT connector with U.FL-LP-066 plug .................................................... 85
Figure 39: Specifications of U.FL-LP-(V)-040(01) plug .......................................................... 86
Figure 40: Pin assignment (top view on XT55/56) .................................................................90
Figure 41: Typical current consumption vs. return loss in EGSM 900 network...................... 98
Figure 42: Typical current consumption vs. return loss in GSM 1800 network ...................... 99
Figure 43: Typical current consumption vs. return loss in GSM 1900 network ...................... 99
Figure 44: Peak current consumption during transmit burst in EGSM 900 network............. 100
Figure 45: Peak current consumption during transmit burst in GSM 1800 network .............100
Figure 46: Peak current consumption during transmit burst in GSM 1900 network .............101
Figure 47: Typical current consumption vs. return loss........................................................ 102
Figure 48: AT audio programming model............................................................................. 104
Figure 49: XT55/56 – top view .............................................................................................111
Figure 50: XT55/56 bottom view ..........................................................................................111
Figure 51: Mechanical dimensions of XT55/56 .................................................................... 112
Figure 52: Mounting holes on XT55/56 ................................................................................ 113
Figure 53: Recommended dowel .........................................................................................114
Figure 54: Mechanical dimensions of Hirose DF12 connector............................................. 116
Figure 55: Reference equipment for approval...................................................................... 117
Figure 56: Block diagram of XT55/56 for SiRF Demo application........................................ 120
Figure 57: Block diagram of XT55/56 with AVL application (optional) .................................121
Figure 58: XT55/56 tracking phone with external µC (example application) ........................ 122
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Tables
Table 1: XT55/56 key features ............................................................................................... 22
Table 2: GSM coding schemes and maximum net data rates over air interface.................... 24
Table 3: Overview of GSM/GPRS operating modes ..............................................................27
Table 4: Power supply pins of board-to-board connector....................................................... 29
Table 5: AT commands available in Alarm mode................................................................... 35
Table 6: Temperature dependent behavior ............................................................................39
Table 7: Bill of material for external charging circuit............................................................... 43
Table 8: Specifications of recommended battery pack........................................................... 45
Table 9: Comparison Charge-only and Charge mode............................................................ 48
Table 10: AT commands available in Charge-only mode....................................................... 49
Table 11: Wake-up events in NON-CYCLIC and CYCLIC SLEEP modes.............................53
Table 12: State transitions of XT55/56 (except SLEEP mode) ..............................................55
Table 13: DCE-DTE wiring of 1st serial interface (GSM part) ................................................58
Table 14: DCE-DTE wiring of 2nd serial interface (GSM part)............................................... 58
Table 15: Signals of the SIM interface (board-to-board connector) .......................................63
Table 16: Pin assignment of Molex SIM card holder on DSB45 Support Box........................ 65
Table 17: Input control signals of the GSM part of the XT55/56 module................................ 66
Table 18: Coding of the status LED .......................................................................................68
Table 19: ASC0 ring signal.....................................................................................................70
Table 20: Return loss .............................................................................................................81
Table 21: Product specifications of U.FL-R-SMT connector .................................................. 84
Table 22: Material and finish of U.FL-R-SMT connector and recommended plugs ...............85
Table 23: Ordering information for Hirose U.FL Series ..........................................................87
Table 24: Absolute maximum ratings (GSM part) .................................................................. 88
Table 25: Absolute maximum rating (GPS part)..................................................................... 88
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Table 26: Operating temperatures .........................................................................................88
Table 27: Electrical description of application interface .........................................................91
Table 28: Power supply ratings (GSM part) ........................................................................... 96
Table 29: Power supply ratings (GPS part)............................................................................ 97
Table 30: Audio parameters adjustable by AT command ....................................................103
Table 31: Voiceband characteristics (typical)....................................................................... 105
Table 32: Voiceband receive path........................................................................................106
Table 33: Voiceband transmit path....................................................................................... 107
Table 34: Air Interface .......................................................................................................... 108
Table 35: Measured electrostatic values..............................................................................109
Table 36: Summary of reliability test conditions ...................................................................110
Table 37: Ordering information DF12 series ........................................................................ 115
Table 38: Electrical and mechanical characteristics of the Hirose DF12C connector .......... 115
Table 39: List of parts and accessories................................................................................ 124
Table 40: Molex sales contacts (subject to change) ............................................................125
Table 41: Hirose sales contacts (subject to change)............................................................125
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0 Document History
Preceding document: "XT55/56 Hardware Interface Description" Version 02.94
New document: "XT55/56 Hardware Interface Description" Version 02.96
Chapter What is new
1.4 Deleted section “Compliance with international rules and regulations”.
3.3.1.1 Added further details of timing after power-up.
3.6.2, 0,
3.6.5.1
3.12.2.2 Some text changes related to LED behavior in CYCLIC SLEEP mode.
8.2, 8.3 Deleted note on extra FCC certification for OEM products. Changed note on
More detailed description of RTS wake-up.
recommendations for mobile and fixed devices. Added FCC labeling requirements.
Preceding document: "XT55/56 Hardware Interface Description" Version 02.06c
New document: "XT55/56 Hardware Interface Description" Version 02.94
Chapter What is new
Throughout
document
1.4 Added European Directives related to RoHS and WEEE. Updated version numbers
3.5.3 Described charging procedure if battery was deeply discharged.
3.12.3 Same description of RING line behavior for voice, data, fax.
7.2 Deleted screw and washer restrictions for mounting holes of XT55/56.
7.1 Updated figure “Mechanical dimensions of XT55/56”.
10 Siemens ordering numbers changed.
Updated module images.
of several standards.
Preceding document: "XT55/56 Hardware Interface Description" Version 02.06b
New document: "XT55/56 Hardware Interface Description" Version 02.06c
Chapter What is new
1.1 New chapter: Supported Software and Hardware Releases
2.1 New temperature range of GPS part: -25°C to +55°C.
2.2 Corrected GPS processor speed.
4.2 GPS receiver sensitivity has been changed from –138dBm to –142dBm + 2dB.
10 Updated Siemens ordering numbers of the XT55/56 modules.
Preceding document: "XT55/56 Hardware Interface Description" Version 02.06a
New document: "XT55/56 Hardware Interface Description" Version 02.06b
Chapter What is new
4.2 XT55/56 is now supporting the ZDA protocol
8.3 Modified chapter, deleted note on required FCC certification for OEMs, antenna
value has been changes from 1.4dBi to 2.2dBI (GSM 850)
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Preceding document: "XT55 Hardware Interface Description" Version 02.06
New document: "XT55/56 Hardware Interface Description" Version 02.06a
Chapter What is new
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Throughout
document
4.4 Notes about power supply of RTC and SRAM of GPS part.
5.3 Table 23: Corrected Hirose part number U.FL-LP-068.
10 Added Siemens ordering number for module XT56.
Added XT56.
Preceding document: "XT55 Hardware Interface Description" Version 01.06
New document: "XT55 Hardware Interface Description" Version 02.06
Chapter What is new
Throughout the
document
1.2 Updated list of related documents.
Deleted remarks regarding TCP/IP software which is currently not supported.
Preceding document: "XT55 Hardware Interface Description" Version 01.00b
New document: "XT55 Hardware Interface Description" Version 01.06
Chapter What is new
1.4 Updated list of standards.
2.1, 4.2 SDn1, SDn2: both GPS interfaces support baud rates from 4800 … 115200 bps
3.6, 3.12.2 More detailed description of status LED patterns
3.11, 3.11.2
• Use GSM_CCGND line to shield GSM_CCIO line from GSM_CCCLK line.
• Connect a 47 pF capacitor from the GSM_CCIO to the GSM_CCGND line.
3.11.2 Improved Figure 20
4.2 GPS receiver sensitivity has been changed from –142 dBm to –138 dBm
4.7 GPS_RFPC0 and GPS_RFPC1 must be connected as shown in Figure 58 in order
to use the Trickle Power mode, deleted GPS_GPIO9 (T_MARK)
6.4 Added footnote regarding test conditions
6.5.3 Table 31: Sidetone gain at default settings for audio mode 5 and 6 set to - dB
7.2 Figure 53: Improved figure
8.2 Added IC: 267W-XT55/56
9 Figure 58: Two pull-up resistors must be added in order to ensure the correct
voltage level during start-up and reset procedure of the GPS base-band
processor.Added 47 pF capacitor
10 Added new Siemens ordering numbers
Preceding document: "XT55 Hardware Interface Description" Version 01.00a
New document: "XT55 Hardware Interface Description" Version 01.00b
Chapter What is new
General Notes Added note about the use of extracts from SiRF documentation
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Preceding document: "XT55 Hardware Interface Description" Version 01.00
New document: "XT55 Hardware Interface Description" Version 01.00a
Chapter What is new
General Notes Added trademark notice regarding SiRF Software
7.1 Figure 51: Mechanical dimensions of XT55/56 – added new drawing
Preceding document: "XT55/56 Hardware Interface Description" Version 00.02
New document: "XT55/56 Hardware Interface Description" Version 01.00
Chapter What is new
Throughout the
document
2nd cover page New version of General Notes
1.2 Updated list of related documents
1.4 XT55/56 is now fully type approved and marked with the CE conformity label
2 Restructured the chapter, moved figures regarding SiRF Demo, AVL and TCP/IP
3.5.3 Added remark that charging begins again when voltage drops below 4.0V.
6.2 Added footnote regarding heat sink.
7.2 Added further mounting advices
9 New chapter: Design example
---- Deleted chapter: Maximum number of turn-on / turn-off cycles
Renamed “GSM/GPRS part” to “GSM part”
application to Chapter 9
Preceding document: "XT55/56 Hardware Interface Description" Version 00.01
New document: "XT55/56 Hardware Interface Description" Version 00.02
Chapter What is new
Throughout this
document
• Maximum temperature has been changed from +65°C to +70°C.
• Pins have been clearly divided into GPS and GSM pins.
1.2 Updated list of related documents
1.3 Added GPS terms abbreviations
2.1 Added new key features regarding GPS
2.2 Added Figure 56 and Figure 57
3.5.2 Deleted vendor XWODA, battery pack can be obtained from various dealers
4.1 New chapter: Theory of Operation
4.3f Detailed description of GPS operating modes
4.4 Added information regarding the power supply pins of the GPS part
4.5 New chapter: General Purpose Input/Output
4.6 More information regarding the two serial interfaces of the GPS part
4.7 Added a complete list of GPS control signals
4.8 New chapter describing the functionality of the integrated GPS receiver
4.9 New chapter: Operation Procedure
4.10 Detailed description of GPS start-up procedure, coldstart, warmstart and hotstart
6.3 Renamed chapter and corrected pin assignment of B2B connector
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1 Introduction
This document describes the hardware interface of the Siemens XT55/56 module that
connects to the cellular device application and the air interface. As XT55/56 is intended to
integrate with a wide range of application platforms, all functional components are described
in great detail.
This guide therefore covers all information needed to design and set up cellular applications
incorporating the XT55/56 module. It aids rapid retrieval of interface specifications, electrical
and mechanical details and information on the requirements to be considered for integration
of further components.
1.1 Supported Software and Hardware Releases
All XT55/56 02.96 documents refer to the software and hardware releases listed below.
GSM hardware / software: XT55 Release 02.96, XT56 Release 02.96
GPS software: Standard GPS Software Revision 2.3
GPS hardware: Revision 5
The GPS hardware revision number is integrated in the 14-digit
product number printed on the product label. The 5
represents the hardware revision.
th
digit
Figure 1: Product label placed on XT55/56 module
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1.2 Related Documents
[1] XT55 AT Command Set
XT56 AT Command Set
[2] XT55/56 GPS Command Specification
[3] XT55/56 Release Note
[4] XT55 AVL Software User’s Guide
[5] XT55/56 GPS Startup User's Guide
[6] XT55/56 GSM/GPS Evaluation Board Description
[7] GPRS Startup User's Guide
[8] Remote-SAT User's Guide
[9] DSB45 Support Box - Evaluation Kit for Siemens Cellular Engines
[10] Application Note 14: Audio and Battery Parameter Download
[11] Application Note 02: Audio Interface Design
[12] Application Note 22: Using TTY / CTM equipment
[13] Multiplexer User's Guide
[14] Multiplex Driver Developer’s Guide for Windows 2000 and Windows XP
[15] Multiplex Driver Installation Guide for Windows 2000 and Windows XP
[16] Application Note 24: Application Developer’s Guide
[17] Application Note 28: Customer SIM Lock
[18] Application Note 21: Implementing Customer IMEI
Prior to using the XT55/56 engines or upgrading to a new firmware release, be sure to
carefully read the latest product information.
To visit the Siemens Website you can use the following link:
http://www.siemens.com/wm
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1.3 Terms and Abbreviations
Abbreviation Description
AD Analog / Digital
ADC Analog-to-Digital Converter
AFC Automatic Frequency Control
AGC Automatic Gain Control
ANSI American National Standards Institute
ARFCN Absolute Radio Frequency Channel Number
ARP Antenna Reference Point
ASC0 / ASC1 Asynchronous Controller. Abbreviations used for first and second serial interface of
XT55/56
ASIC Application Specific Integrated Circuit
B Thermistor Constant
B2B Board-to-board connector
BER Bit Error Rate
BTS Base Transceiver Station
CB or CBM Cell Broadcast Message
CE Conformité Européene (European Conformity)
CHAP Challenge Handshake Authentication Protocol
CPU Central Processing Unit
CS Coding Scheme
CSD Circuit Switched Data
CTS Clear to Send
DAC Digital-to-Analog Converter
DAI Digital Audio Interface
dBW Decibel per Watt
dBm0 Digital level, 3.14dBm0 corresponds to full scale, see ITU G.711, A-law
DCE Data Communication Equipment (typically modems, e.g. Siemens GSM engine)
DCS 1800 Digital Cellular System, also referred to as PCN
DGPS Differential GPS
DOP Dilution of Precision
DRX Discontinuous Reception
DSB Development Support Box
DSP Digital Signal Processor
DSR Data Set Ready
DTE Data Terminal Equipment (typically computer, terminal, printer or, for example, GSM
application)
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Abbreviation Description
DTR Data Terminal Ready
DTX Discontinuous Transmission
EFR Enhanced Full Rate
EGSM Enhanced GSM
EMC Electromagnetic Compatibility
ESD Electrostatic Discharge
ETS European Telecommunication Standard
FCC Federal Communications Commission (U.S.)
FDMA Frequency Division Multiple Access
FR Full Rate
GGA GPS Fixed Data
GMSK Gaussian Minimum Shift Keying
GPRS General Packet Radio Service
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GPS Global Positioning System
GSM Global Standard for Mobile Communications
HiZ High Impedance
HR Half Rate
I/O Input/Output
IC Integrated Circuit
IF Intermediate Frequency
IMEI International Mobile Equipment Identity
ISO International Standards Organization
ITU International Telecommunications Union
kbps kbits per second
LED Light Emitting Diode
Li-Ion Lithium-Ion
LNA Low Noise Amplifier
Mbps Mbits per second
MMI Man Machine Interface
MO Mobile Originated
MS Mobile Station (GSM engine), also referred to as TE
MSISDN Mobile Station International ISDN number
MSK Minimum Shift Key
MT Mobile Terminated
NTC Negative Temperature Coefficient
NMEA National Maritime Electronics Association
OEM Original Equipment Manufacturer
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Abbreviation Description
PA Power Amplifier
PAP Password Authentication Protocol
PBCCH Packet Switched Broadcast Control Channel
PCB Printed Circuit Board
PCL Power Control Level
PCM Pulse Code Modulation
PCN Personal Communications Network, also referred to as DCS 1800
PCS Personal Communication System, also referred to as GSM 1900
PDU Protocol Data Unit
PLL Phase Locked Loop
PPP Point-to-point protocol
PRN Pseudo-Random Noise Number – The identity of GPS satellites
PSU Power Supply Unit
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R&TTE Radio and Telecommunication Terminal Equipment
RAM Random Access Memory
RF Radio Frequency
RMS Root Mean Square (value)
ROM Read-only Memory
RP Receive Protocol
RTC Real Time Clock
RTCM Radio Technical Commission for Maritime Services
Rx Receive Direction
SA Selective Availability
SAR Specific Absorption Rate
SELV Safety Extra Low Voltage
SIM Subscriber Identification Module
SMS Short Message Service
SPI Service Provider Interface
SRAM Static Random Access Memory
TA Terminal adapter (e.g. GSM engine)
TDMA Time Division Multiple Access
TE Terminal Equipment, also referred to as DTE
Tx Transmit Direction
UART Universal asynchronous receiver-transmitter
URC Unsolicited Result Code
USSD Unstructured Supplementary Service Data
VSWR Voltage Standing Wave Ratio
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Abbreviation Description
WAAS Wide Area Augmentation System
Phonebook abbreviations
FD SIM fixdialing phonebook
LD SIM last dialing phonebook (list of numbers most recently dialed)
MC Mobile Equipment list of unanswered MT calls (missed calls)
ME Mobile Equipment phonebook
ON Own numbers (MSISDNs) stored on SIM or ME
RC Mobile Equipment list of received calls
SM SIM phonebook
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1.4 Type Approval
XT55/56 has been approved to comply with the directives and standards listed below and is
labeled with the CE conformity mark.
European directives
99/05/EC “Directive of the European Parliament and of the council of 9 March
1999 on radio equipment and telecommunications terminal equipment
and the mutual recognition of their conformity”, in short referred to as
89/336/EC Directive on electromagnetic compatibility
73/23/EC Directive on electrical equipment designed for use within certain
2002/95/EC Directive of the European Parliament and of the Council of 27
2002/96/EC Directive of the European Parliament and of the Council on waste
2003/108/EC Directive of the European Parliament and of the Council of 8
Standards of North American Type Approval
CFR Title 47 “Code of Federal Regulations, Part 15, Part 22 and Part 24
NAPRD.03 “Overview of PCS Type certification review board
Mobile Equipment Type Certification and IMEI control”
PCS Type Certification Review board (PTCRB)
Standards of European Type Approval
3GPP TS 51.010-1 “Digital cellular telecommunications system (Phase 2); Mobile Station
ETSI EN 301 511 “V7.0.1 Standard
GCF-CC “Global
ETSI EN 301 489-1 “V1.2.1
R&TTE Directive 1999/5/EC
voltage limits (Low Voltage Directive)
January 2003 on the restriction of the use of certain hazardous
substances in electrical and electronic equipment (RoHS)
electrical and electronic equipment (WEEE)
December 2003 amending directive 2002/96/ec on waste electrical
and electronic equipment (WEEE)
(Telecommunications, PCS)”; US Equipment Authorization FCC
(MS) conformance specification”.
Candidate Harmonized European Standard (Telecommunications
series) Global System for Mobile communications (GSM); Harmonized
standard for mobile stations in the GSM 900 and DCS 1800 bands
covering essential requirements under article 3.2 of the R&TTE
directive (1999/5/EC) (GSM 13.11 version 7.0.1 Release 1998)”
Certification Forum - Certification Criteria” V3.18.0
Candidate Harmonized European Standard (Tele-
communications
series) Electro Magnetic Compatibility and Radio
spectrum Matters (ERM); Electro Magnetic Compatibility (EMC) standard
for radio equipment and services; Part 1: Common Technical
Requirements”
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ETSI EN 301 489-07 “V1.2.1 Electro Magnetic Compatibility and Radio spectrum Matters
(ERM); Electro Magnetic Compatibility (EMC) standard for radio
equipment and services; Part 7: Specific conditions for mobile and
portable radio and ancillary equipment of digital cellular radio telecommunications systems (GSM and DCS)”
EN 60 950 Safety of information technology equipment (2000)
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Requirements of quality
IEC 60068 Environmental testing
DIN EN 60529 IP codes
SAR requirements specific to portable mobiles
Mobile phones, PDAs or other portable transmitters and receivers incorporating a GSM
module must be in accordance with the guidelines for human exposure to radio frequency
energy. This requires the Specific Absorption Rate (SAR) of portable XT55/56 based
applications to be evaluated and approved for compliance with national and/or international
regulations.
Since the SAR value varies significantly with the individual product design manufacturers are
advised to submit their product for approval if designed for portable use. For European and
US markets the relevant directives are mentioned below. It is the responsibility of the
manufacturer of the final product to verify whether or not further standards, recommendations
or directives are in force outside these areas.
Products intended for sale on US markets
ES 59005/ANSI C95.1 Considerations for evaluation of human exposure to Electromagnetic
Fields (EMFs) from Mobile Telecommunication Equipment (MTE) in
the frequency range 30MHz-6GHz
Products intended for sale on European markets
EN 50360 Product standard to demonstrate the compliance of mobile phones
with the basic restrictions related to human exposure to
electromagnetic fields (300MHz - 3GHz)
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1.5 Safety Precautions
The following safety precautions must be observed during all phases of the operation, usage,
service or repair of any cellular terminal or mobile incorporating XT55/56. Manufacturers of
the cellular terminal are advised to convey the following safety information to users and
operating personnel and to incorporate these guidelines into all manuals supplied with the
product. Failure to comply with these precautions violates safety standards of design,
manufacture and intended use of the product. Siemens AG assumes no liability for customer
failure to comply with these precautions.
When in a hospital or other health care facility, observe the restrictions on the
use of mobiles. Switch the cellular terminal or mobile off, if instructed to do so
by the guidelines posted in sensitive areas. Medical equipment may be
sensitive to RF energy.
The operation of cardiac pacemakers, other implanted medical equipment
and hearing aids can be affected by interference from cellular terminals or
mobiles placed close to the device. If in doubt about potential danger, contact
the physician or the manufacturer of the device to verify that the equipment is
properly shielded. Pacemaker patients are advised to keep their hand-held
mobile away from the pacemaker, while it is on.
Switch off the cellular terminal or mobile before boarding an aircraft. Make
sure it cannot be switched on inadvertently. The operation of wireless
appliances in an aircraft is forbidden to prevent interference with
communications systems. Failure to observe these instructions may lead to
the suspension or denial of cellular services to the offender, legal action, or
both.
Do not operate the cellular terminal or mobile in the presence of flammable
gases or fumes. Switch off the cellular terminal when you are near petrol
stations, fuel depots, chemical plants or where blasting operations are in
progress. Operation of any electrical equipment in potentially explosive
atmospheres can constitute a safety hazard.
Your cellular terminal or mobile receives and transmits radio frequency
energy while switched on. Remember that interference can occur if it is used
close to TV sets, radios, computers or inadequately shielded equipment.
Follow any special regulations and always switch off the cellular terminal or
mobile wherever forbidden, or when you suspect that it may cause
interference or danger.
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Road safety comes first! Do not use a hand-held cellular terminal or mobile
when driving a vehicle, unless it is securely mounted in a holder for handsfree
operation. Before making a call with a hand-held terminal or mobile, park the
vehicle.
Handsfree devices must be installed by qualified personnel. Faulty installation
or operation can constitute a safety hazard.
IMPORTANT!
SOS
Cellular terminals or mobiles operate using radio signals and cellular
networks. Because of this connection cannot be guaranteed at all times under
all conditions. Therefore, you should never rely solely upon any wireless
device for essential communications, for example emergency calls.
Remember, in order to make or receive calls, the cellular terminal or mobile
must be switched on and in a service area with adequate cellular signal
strength.
Some networks do not allow for emergency calls if certain network services or
phone features are in use (e.g. lock functions, fixed dialing etc.). You may
need to deactivate those features before you can make an emergency call.
Some networks require that a valid SIM card be properly inserted in the
cellular terminal or mobile.
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2 Product Concept
Designed for use on any GSM network in the world, Siemens XT55 is a tri-band GSM/GPRS
engine that works on the three frequencies GSM 900 MHz, GSM 1800 MHz and GSM
1900 MHz and supports also GPS technology for satellite navigation. XT56 is a tri-band
GSM/GPRS engine that works on the three frequencies GSM 850MHz, GSM 1800 MHz and
GSM 1900 MHz and supports also GPS technology for satellite navigation. XT55/56 features
GPRS multislot class 10 and supports the GPRS coding schemes CS-1, CS-2, CS-3 and
CS-4.
The compact design of the XT55/56 module makes it easy to integrate GSM / GPRS and
GPS as an all-in-one solution. It saves significantly both time and cost for integration of
additional hardware components.
The integrated GPS module provides instant location information using satellite signals to
enable users to ascertain where they are anywhere in the world. It consists of a fully
integrated RF receiver and a 12 channel baseband.
The tiny XT55/56 module incorporates all you need to create high-performance GSM/GPRS
solutions: baseband processor, power supply ASIC, complete radio frequency circuit
including a power amplifier and antenna interface. The power amplifier is directly fed from the
supply voltage GSM_BATT+. A compact “stacked FLASH / SRAM” device stores the
XT55/56 software in the flash memory section, and static RAM section provides the
additional storage capacity required by GPRS connectivity.
The physical interface to the cellular application is made through a board-to-board connector.
It consists of 80 pins, required for controlling the unit, receiving GPS location data,
transferring data and audio signals and providing power supply lines.
XT55/56 comprises two serial GSM interfaces (ASC0 and ASC1) and two serial GPS
interfaces (Serial data 1 and Serial data 2) giving you maximum flexibility for easy integration
with the Man-Machine Interface (MMI).
An extremely versatile audio concept offers various audio interfaces, each available on the
board-to-board connector: a digital audio interface (DAI) and two analog audio interfaces.
Using AT commands you can easily switch back and forth and select different audio modes.
The external dual-band or triple-band GSM antenna can be connected optionally to a
connector on the top side or to a pad on the bottom side. A separate GPS antenna must be
connected to the GPS part of the module in order to properly receive satellite data.
For battery powered applications, XT55/56 features a charging control which can be used to
charge a Li-Ion battery. The charging circuit must be implemented outside the module on the
application platform.
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2.1 XT55/56 Key Features at a Glance
Table 1: XT55/56 key features
Feature Implementation
Power supply Supply voltage 3.3V – 4.8V for the GSM / GPRS module
Separate power supply source: 3.3V ± 5% for the GPS device
Power saving (GSM) Minimizes power consumption in SLEEP mode
Power saving (GPS) Trickle Power™ / Push-to-Fix mode
Charging Supports charging control for Li-Ion battery for the GSM part of the module
Frequency bands
GSM class Small MS
Transmit power
GPRS connectivity
GPS features
Temperature range:
Temperature control
and auto switch-off
DATA GPRS:
CSD:
WAP:
SMS
• XT55 Tri-band: EGSM 900, GSM 1800, GSM 1900
• XT56 Tri-band: GSM 850, GSM 1800, GSM 1900
• Compliant to GSM Phase 2/2+
• Class 4 (2W) at EGSM 900 and GSM 850
• Class 1 (1W) at GSM 1800 and GSM 1900
• GPRS multi-slot class 10
• GPRS mobile station class B
• GPS receiver with SiRFstar Ile/LP chip set
• Processor type ARM7/TDMI
• Sirf GSW2, version 2.3
• Normal operation: -20°C to +55°C
• Restricted operation: -25°C to -20°C and +55°C to +70°C
• Constant temperature control prevents damage to XT55/56 when the
specified temperature is exceeded. When an emergency call is in
progress the automatic temperature shutdown functionality is
deactivated.
• GPRS data downlink transfer: max. 85.6 kbps (see Table 2)
• GPRS data uplink transfer: max. 42.8 kbps (see Table 2
• Coding scheme: CS-1, CS-2, CS-3 and CS-4
• XT55/56 supports the two protocols PAP (Password Authentication
Protocol) and CHAP (Challenge Handshake Authentication Protocol)
commonly used for PPP connections.
• Support of Packet Switched Broadcast Control Channel (PBCCH) allows
you to benefit from enhanced GPRS performance when offered by the
network operators.
• CSD transmission rates: 2.4, 4.8, 9.6, 14.4 kbps, non-transparent, V.110
• Unstructured Supplementary Services Data (USSD) support
WAP compliant
• MT, MO, CB, Text and PDU mode
• SMS storage: SIM card plus 25 SMS locations in the mobile equipment
• Transmission of SMS alternatively over CSD or GPRS. Preferred mode
can be user-defined.
MMS MMS compliant
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Feature Implementation
FAX Group 3: Class 1, Class 2
SIM interface
Supported SIM card: 3V
External SIM card reader has to be connected via interface connector (note
that card reader is not part of XT55/56)
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External antenna
GSM / GPRS:
GPS:
Audio interfaces Two analog audio interfaces, one digital audio interface (DAI)
Audio features Speech codec modes:
Two serial GSM
interfaces:
ASC0, ASC1
Connected via 50 Ohm antenna connector or antenna pad.
Separate GPS antenna connector. See Figure 49 for details.
• Half Rate (ETS 06.20)
• Full Rate (ETS 06.10)
• Enhanced Full Rate (ETS 06.50 / 06.60 / 06.80)
• Adaptive Multi Rate (AMR)
Handsfree operation
• Echo cancellation
• Noise reduction
• 2.65V level, bi-directional bus for AT commands and data
• ASC0 – full-featured 8-wire serial interface. Supports RTS0/CTS0
hardware handshake and software XON/XOFF flow control. Multiplex
ability according to GSM 07.10 Multiplexer Protocol.
• ASC1 - 4-wire serial interface. Supports RTS1/CTS1 hardware
handshake and software XON/XOFF flow control.
• Baud rate: 300bps ... 230kbps on ASC0 and ASC1
• Autobauding (on ASC0 only) detects 1200, 2400, 4800, 9600, 19200,
38400, 57600, 115200, 230400 bps
Two serial GPS
interfaces: SDn1, SDn2
Phonebook
management
SIM Application Toolkit Supports SAT class 3, GSM 11.14 Release 98, support of letter class “c”
Ringing tones Offers a choice of 7 different ringing tones / melodies, easily selectable with
Real time clock Implemented
Timer function Programmable via AT command
Support of TTY/CTM To benefit from TTY communication via GSM, CTM equipment can be
Physical characteristics Size: 35.0 ± 0.15mm x 53.0 ± 0.15mm x 5.1 ± 0.15mm
RoHS, WEEE All hardware components are fully compliant with the EU RoHS and WEEE
Firmware upgrade XT55/56 firmware upgradable over serial interface
Evaluation kit The DSB45 Support Box is an evaluation kit designed to test and type
• Baud rate: 4800 … 115200 bps on SD1 and SD2 (default setting on both
interfaces: 9600 bps)
Supported phonebook types: SM, FD, LD, MC, RC, ON, ME
AT command
connected to one of the three audio interfaces.
Weight: 11g
Directives
approve the GSM part of Siemens cellular engines and provide a sample
configuration for application engineering. See Chapter 10 for details.
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Table 2: GSM coding schemes and maximum net data rates over air interface
Coding scheme 1 Timeslot 2 Timeslots 4 Timeslots
CS-1: 9.05 kbps 18.1 kbps 36.2 kbps
CS-2: 13.4 kbps 26.8 kbps 53.6 kbps
CS-3: 15.6 kbps 31.2 kbps 62.4 kbps
CS-4: 21.4 kbps 42.8 kbps 85.6 kbps
Please note that the values stated above are maximum ratings which, in practice, are influenced by a
great variety of factors, primarily, for example, traffic variations and network coverage.
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2.2 Circuit Concept
The XT55/56 module comprises the following major functional components:
GSM / GPRS baseband block:
• Baseband controller operating at 26MHz
• Power supply ASIC
• Stacked Flash / SRAM
• Application interface (board-to-board connector)
GSM RF block:
• RF transceiver
• RF power amplifier / FEM
• Antenna connector
GPS block:
• Processor type: ARM7/TDMI
• Processor speed: depending on GPS software, e.g. 12.277MHz for the standard GPS
software supplied by Siemens
GPS RF block:
• GPS receiver with SiRFstar Ile/LP chip set
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GSM antenna
GSM –
GSM module
Modul
ASC0
ASC1
XT55
XT56
GSM_RXD0
GSM_TXD0
6 Modem
Status lines
GSM_RXD1
GSM_TXD1
GSM_RTS1
GSM_CTS1
Active GPS antenna
GPS –
GPS module
Modul
Serial data 2 Serial data 1
SDO2 SDI2
SDI1 SDO1
80 pin B2B
Customer application
Figure 2: Block diagram of serial interface concept
80 pin B2B
Serial 1
GSM
Serial 0
GSM
Serial 2
GPS
Serial 1
GPS
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3 GSM Application Interface
The GSM part of the XT55/56 module incorporates several sub-interfaces described in the
following chapters:
• Power supply and charging control (see Chapters 3.2 and 3.3)
• Dual serial GSM interface (see Chapter 3.9)
• Two analog audio interfaces and a digital audio interface (see Chapter 3.10)
• SIM interface (see Chapter 3.11)
Electrical and mechanical characteristics of the board-to-board connector are specified in
Chapter 7.3. Ordering information for mating connectors and cables are included.
3.1 GSM/GPRS Operating Modes
The table below briefly summarizes the various operating modes referred to in the following
chapters. All information regarding GPS/GPRS operating modes are available in Chapter
4.3.
Table 3: Overview of GSM/GPRS operating modes
Mode Function
Normal operation
GSM / GPRS SLEEP Various powersave modes set with AT+CFUN
command.
Software is active to minimum extent. If the module was
registered to the GSM network in IDLE mode, it is
registered and paging with the BTS in SLEEP mode,
too. Power saving can be chosen at different levels:
The NON-CYCLIC SLEEP mode (AT+CFUN=0)
disables the AT interface. The CYCLIC SLEEP modes
AT+CFUN=5, 6, 7, 8 and 9 alternatively activate and
deactivate the AT interfaces to allow permanent access
to all AT commands.
GSM IDLE Software is active. Once registered to the GSM
network, paging with BTS is carried out. The module is
ready to send and receive.
GSM TALK Connection between two subscribers is in progress.
Power consumption depends on network coverage
individual settings, such as DTX off/on, FR/EFR/HR,
hopping sequences, antenna.
GPRS IDLE Module is ready for GPRS data transfer, but no data is
currently sent or received. Power consumption depends
on network settings and GPRS configuration (e.g.
multislot settings).
GPRS DATA GPRS data transfer in progress. Power consumption
depends on network settings (e.g. power control level),
uplink / downlink data rates and GPRS configuration
(e.g. used multislot settings).
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Mode Function
POWER DOWN Normal shutdown after sending the AT^SMSO command.
The Power Supply ASIC (PSU-ASIC) disconnects the supply voltage from the
baseband part of the circuit. Only a voltage regulator in the PSU-ASIC is active
for powering the RTC. Software is not active. The serial interfaces are not
accessible.
Operating voltage (connected to GSM_BATT+) remains applied.
Alarm mode Restricted operation launched by RTC alert function while the module is in
POWER DOWN mode. Module will not be registered to GSM network. Limited
number of AT commands is accessible.
Charge-only mode Limited operation for battery powered applications. Enables charging while
module is detached from GSM network. Limited number of AT commands is
accessible. There are several ways to launch Charge-only mode:
• From POWER DOWN mode: Connect charger to the charger input pin of the
external charging circuit and the module’s GSM_POWER pin when XT55/56
was powered down by AT^SMSO.
• From Normal mode: Connect charger to the charger input pin of the external
charging circuit and the module’s GSM_POWER pin, then enter AT^SMSO.
Charge mode
during normal
operation
Normal operation (SLEEP, IDLE, TALK, GPRS IDLE, GPRS DATA) and
charging running in parallel. Charge mode changes to Charge-only mode when
the module is powered down before charging has been completed.
See Table 11 and Table 12 for the various options of waking up the GSM part of the XT55/56 module
and proceeding from one mode to another.
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3.2 Power Supply
The power supply for the GSM part of the XT55/56 module has to be a single voltage source
of V
GSM_BATT
which typically rises to 1.6A.
All the key functions for supplying power to the device are handled by an ASIC power supply.
The ASIC provides the following features:
• Stabilizes the supply voltages for the GSM baseband using low drop linear voltage
regulators.
• Controls the module's power up and power down procedures.
A watchdog logic implemented in the baseband processor periodically sends signals to
the ASIC, allowing it to maintain the supply voltage for all digital XT55/56 components.
Whenever the watchdog pulses fail to arrive constantly, the module is turned off.
• Delivers, across the GSM_VDD pin, a regulated voltage of 2.9V. The output voltage
GSM_VDD may be used to supply, for example, an external LED or a level shifter.
However, the external circuitry must not cause any spikes or glitches on voltage
GSM_VDD. This voltage is not available in POWER DOWN mode. Therefore, the
GSM_VDD pin can be used to indicate whether or not GSM part of the XT55/56 module
is in POWER DOWN mode.
• Provides power to the SIM interface.
The RF power amplifier is driven directly from GSM_BATT+.
+= 3.3V...4.8V. It must be able to provide sufficient current in a transmit burst
3.2.1 Power Supply Pins on the Board-to-Board Connector
Five GSM_BATT+ pins of the board-to-board connector are dedicated to connect the supply
voltage, five GND pins are recommended for grounding. The values stated below must be
measured directly at the reference points on the XT55/56 board (TP GSM_BATT+ and TP
GND illustrated in Figure 50).
The GSM_POWER and GSM_CHARGE pins serve as control signals for charging a Li-Ion
battery. GSM_VDDLP can be used to back up the RTC.
Table 4: Power supply pins of board-to-board connector
Signal name I/O Description Parameter
GSM_BATT+ I/O Positive operating voltage
Reference points are the
test points
GND - Ground 0 V
GSM_POWER I This line signals to the
processor that the
charger is connected.
GSM_CHARGE O Control signal for external
charging transistor
3.3 V...4.8 V, I
The minimum operating voltage must not fall
below 3.3 V, not even in case of voltage
drop.
≤ 1.6 A during transmit burst
typ
GSM_VDDLP I/O Can be used to back up
the RTC when V
is not applied.
See Chapter 3.8
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GSM_BATT+
U
UIN = 2.0 V...5.5 V
Ri = 1kΩ
I
in,max
OUT,max
= 30µA
< V
GSM_BATT+
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3.2.2 Minimizing Power Losses
When designing the power supply for your application please pay specific attention to power
losses. Ensure that the input voltage V
GSM_BATT+
the XT55/56 board, not even in a transmit burst where current consumption can rise to
typical peaks of 1.6A. It should be noted that the GSM part of the XT55/56 module switches
off when exceeding these limits. Any voltage drops that may occur in a transmit burst should
not exceed 400mV. For further details see Chapter 6.4.
The best approach to reducing voltage drops is to use a board-to-board connection as
recommended, and a low impedance power source. The resistance of the power supply lines
on the host board and of a battery pack should also be considered.
Note: If the application design requires an adapter cable between both board-to-board
connectors, use a cable as short as possible in order to minimize power losses.
Example: If the length of the cable reaches the maximum length of 200mm, this connection
may cause, for example, a resistance of 50m in the GSM_BATT+ line and
50m in the GND line. As a result, a 1.6A transmit burst would add up to a total
voltage drop of 160mV. Plus, if a battery pack is involved, further losses may
occur due to the resistance across the battery lines and the internal resistance of
the battery including its protective circuit.
never drops below 3.3V on the GSM part of
Transmit
burst 1.6A
GSM_BATT+
min. 3.3V
Transmit
burst 1.6A
Ripple
Drop
Figure 3: Power supply limits during transmit burst
The input voltage V
GSM_BATT+
must be measured directly at the test points on the XT55/56
board (TP GSM_BATT+ and TP GND illustrated in Figure 50).
3.2.3 Monitoring Power Supply
To help you monitor the supply voltage you can use the AT^SBV command which returns the
voltage measured at TP GSM_BATT+ and GND.
The voltage is continuously measured at intervals depending on the operating mode on the
RF interface. The duration of measuring ranges from 0.5s in TALK/DATA mode up to 50s
when the GSM part of the XT55/56 is in IDLE mode or Limited Service (deregistered). The
displayed voltage (in mV) is averaged over the last measuring period before the AT^SBV
command was executed.
For details please refer to [1].
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