HUAWEI

Huawei GTM900 GSM/GPRS Wireless Module

Product Description

V100R001

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Huawei GTM900 GSM/GPRS Wireless Module
Product Description

Manual Version T2-032598-20050320-C-1.10

Product Version V100R001

BOM 31250298

Huawei Technologies Co., Ltd. provides customers with comprehensive technical support
and service. Please feel free to contact our local office or company headquarters.

Huawei Technologies Co., Ltd.

Address: Huawei Industrial Base, Bantian, Longgang, Shenzhen 518129, P.R.China

Tel: +86-755-28780808

Global Hotline: +86-755-28560808

Website: www.huawei.com

E-mail:mobile@huawei.com

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Copyright © 2005 Huawei Technologies Co., Ltd.

All Rights Reserved

No part of this manual may be reproduced or transmitted in any form or by any

means without prior written consent of Huawei Technologies Co., Ltd.

Trademarks

, HUAWEI, C&C08, EAST8000, HONET, , ViewPoint, INtess, ETS, DMC,

TELLIN, InfoLink, Netkey, Quidway, SYNLOCK, Radium, M900/M1800,
TELESIGHT, Quidview, Musa, Airbridge, Tellwin, Inmedia, VRP, DOPRA, iTELLIN,
HUAWEI OptiX, C&C08 iNET, NETENGINE, OptiX, iSite, U-SYS, iMUSE, OpenEye,
Lansway, SmartAX, infoX, TopEng are trademarks of Huawei Technologies Co.,
Ltd.

All other trademarks mentioned in this manual are the property of their respective
holders.

Notice

The information in this manual is subject to change without notice. Every effort has
been made in the preparation of this manual to ensure accuracy of the contents, but
all statements, information, and recommendations in this manual do not constitute
the warranty of any kind, express or implied.

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Summary of Updates

This section provides the update history of this manual and introduces the contents of
subsequent updates.

Update History

This manual is updated for a major product version to maintain consistency with system
hardware or software versions and to incorporate customer suggestions.

Manual Version Notes

T2-032598-20050320-C-1.10 Initial field trial release

Relevant Documents

The manuals related to Huawei GTM900 GSM/GPRS Wireless Module are introduced
in the table below:

Manual name Description

Huawei GTM900 GSM/GPRS Wireless Introduces Huawei GTM900 GSM/GPRS Wireless
Module Product Description Module in terms of specifications and interface signals

Huawei GTM900 GSM/GPRS Wireless Describes the AT commands related to Huawei GTM900
Module AT Command Set GSM/GPRS Wireless Module

Updates of Contents

None

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About This Manual

Release Notes

The product version that corresponds to the manual is GTM900 V100R001.

Organization

The manual consists of six chapters.

Chapter 1 Overview of GTM900 presents physical specifications, functional

architecture and application of GTM900.

Chapter 2 Interface Signals describes the interface signals of GTM900.

Chapter 3 Electrical Characteristics of Interfaces presents the electrical

characteristics of the interfaces, including absolute maximum ratings, recommended
operating conditions and power supply characteristics.

Chapter 4 Interface Application presents the application of the interfaces, including

UART interface, SIM interface, audio interface, ringer interface and power supply
interface.

Chapter 5 Operating Process presents the operating process of GTM900, including

powering on/off, software upgrade and data services.

Chapter 6 Acronyms and Abbreviations

Intended Audience

The manual is intended for the following readers:

z Anyone who are interested in Huawei GTM900 GSM/GPRS Wireless Module,
regarding its features, applications, structure and specifications.

Conventions

The manual uses the following conventions:

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I. General conventions

Convention Description
Arial Normal paragraphs are in Arial.

Arial Narrow Warnings, Cautions, Notes and Tips are in Arial Narrow.
Boldface Headings are in Boldface.
Terminal Display is in Courier New; message input by the user via the
Terminal Display
terminal is in boldface.

II. Symbols

Eye-catching symbols are also used in the manual to highlight the points worthy of
special attention during the operation. They are defined as follows:

Caution, Warning, Danger: Means reader be extremely careful during the

operation.

Note, Comment, Tip, Knowhow, Thought: Means a complementary description.

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Product Description
Huawei GTM900 GSM/GPRS Wireless Module Table of Contents

Table of Contents

Chapter 1 Overview of GTM900 ................................................................................................... 1-1

1.1 About This Chapter ............................................................................................................ 1-1
1.2 Intended Use of GTM900 .................................................................................................. 1-1
1.3 Physical specifications of GTM900.................................................................................... 1-1
1.4 Functions and Services Supported by GTM900................................................................ 1-2
1.4.1 Functional Characteristics of GTM900.................................................................... 1-2
1.4.2 Services Supported by GTM900 ............................................................................. 1-2
1.5 Functional Architecture of GTM900 ................................................................................... 1-3
1.6 Application of GTM900 ...................................................................................................... 1-3
1.6.1 Application to Terminal-Type Fixed Stations .......................................................... 1-3
1.6.2 Application to Phone-Type Fixed Stations .............................................................. 1-4
1.6.3 Application to Vehicle-Mounted Stations and Public Telephones........................... 1-5

Chapter 2 Interface Signals .......................................................................................................... 2-1

2.1 About This Chapter ............................................................................................................ 2-1
2.2 Interfaces of Signal Connector on GTM900 ...................................................................... 2-1
2.2.1 Interface Signals...................................................................................................... 2-1
2.2.2 Design of Signal Connector .................................................................................... 2-3
2.3 Antenna Interface............................................................................................................... 2-3

Chapter 3 Electrical Characteristics of Interfaces ..................................................................... 3-1

3.1 About This Chapter ............................................................................................................ 3-1
3.2 Absolute Maximum Ratings ............................................................................................... 3-1
3.3 Recommended Operating Conditions ............................................................................... 3-1
3.4 Power Supply Characteristics............................................................................................ 3-2
3.4.1 Input Power ............................................................................................................. 3-2
3.4.2 Operating Current.................................................................................................... 3-2

Chapter 4 Interface Application ................................................................................................... 4-1

4.1 About This Chapter ............................................................................................................ 4-1
4.2 UART Interface .................................................................................................................. 4-1
4.3 SIM Interface...................................................................................................................... 4-2
4.4 Audio Interface .................................................................................................................. 4-2
4.5 Ringer Interface................................................................................................................. 4-4
4.6 Power Supply Interface...................................................................................................... 4-5

Chapter 5 Operating Process....................................................................................................... 5-1

5.1 About This Chapter ............................................................................................................ 5-1
5.2 Powering on/off GTM900................................................................................................... 5-1
5.2.1 Powering UP GTM900 ............................................................................................ 5-1

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Huawei GTM900 GSM/GPRS Wireless Module Table of Contents

5.2.2 Powering Down GTM900 ........................................................................................ 5-1

5.3 Software Upgrade of GTM900........................................................................................... 5-2
5.4 Data Services of GTM900 ................................................................................................. 5-2
5.5 Services Presentation Diagram of GTM900 ...................................................................... 5-2

Chapter 6 Acronyms and Abbreviations..................................................................................... 6-1

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 1 Overview of GTM900

Chapter 1 Overview of GTM900

1.1 About This Chapter

This chapter presents the GTM900 GSM/GPRS wireless module from the following
aspects:
z Intended Use of GTM900
z Physical specifications of GTM900
z Functions and Services Supported by GTM900
z Functional Architecture of GTM900
z Application of GTM900

1.2 Intended Use of GTM900

Huawei GTM900 is a type of tri-band wireless module supporting both GSM and GPRS.
The module supports both standard AT commands and enhanced AT commands, and
provides a variety of voice services and data services. It is an ideal solution to
high-speed data transmission.

1.3 Physical specifications of GTM900

The physical specifications of GTM900 are listed in Table 1-1.

Table 1-1 Physical specifications of GTM900

Item Index
Weight 10 g
Dimensions (including the Height 56.5 mm
shielding box)
Width 36 mm
Depth 3 mm

Figure 1-1 shows the appearance of GTM900.

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 1 Overview of GTM900

Figure 1-1 Appearance of GTM900

1.4 Functions and Services Supported by GTM900

1.4.1 Functional Characteristics of GTM900

GTM900 has the following functional characteristics:

z Supporting the single band operation at 800 MHz
z Supporting the dual band operation at 900 MHz and 1800 MHz
z Supporting the tri-band operation at 800 MHz, 900 MHz, and 1800 MHz
z Easy switchover between the above three bands through software
z Supporting 850MHz and 1900 MHz through hardware replacement
z Providing the UART interface
z Supporting the maximum rate of the serial interfaces at 115.2 kbps
z Supporting the packet data services of GPRS CLASS 10
z Supporting speech encoding in the modes of FR, HR, EFR, and AMR
z Supporting both standard AT command sets and enhanced AT command sets
z Providing interfaces, including UART, Audio, SIM, Power, Control and ADC

1.4.2 Services Supported by GTM900

GTM900 supports the following services:

z High quality voice services and speech encoding in the modes of FR, HR, EFR,
and AMR
z Wireless data services, including CS data services and PS data services
z Packet data services of GPRS CLASS 10
z SMS with MT and MO supported
z Supplementary Services, including call display, call transfer, call forward, call hold,
call wait, and three-party conversation

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 1 Overview of GTM900

z Trunking services, including voice group call, point-to-point communications, and

private call.

1.5 Functional Architecture of GTM900

Figure 1-2 illustrates the functional architecture of GTM900.

Digital baseband RF antenna switching

Audio processing unit AD/DA conversion unit
processing unit unit

Serial interface Analog baseband

CPU processing unit RF Tx/Rx unit
processing unit processing unit

Power supply Program and data RF signal power

SIM processing unit
management unit storage unit amplifying unit

Figure 1-2 Functional architecture of GTM900

Through AT command sets, GTM900 communicates with the external CPU over the
URAT interface, performing such functions as radio transmit and receive, baseband
processing, and audio processing. The peripheral equipment like keyboard and LCD is
controlled by the external CPU.
The realization in the above way features:
z Simple interfaces
z A variety of terminal products developed by the user with different types of
keyboards and LCDs

1.6 Application of GTM900

1.6.1 Application to Terminal-Type Fixed Stations

When applying GTM900 to a terminal-type fixed station, you need an external CPU.
The CPU performs:
z Configuration of the subscriber line interface circuit (SLIC) chip
z Power supply management
z Communications at the serial interfaces
GTM900 performs the other functions.
See Figure 1-3 for the functional architecture of the terminal-type fixed station.

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 1 Overview of GTM900

AUDIO
SLIC
ANT

UART Battery charge/

G CPU discharge and
T management
M
9 SIM
SIM Serial interface
0
0
IRDA
IRDA

Power-on and
indicator control
POWER
POWER

Figure 1-3 Functional architecture of terminal-type fixed station

1.6.2 Application to Phone-Type Fixed Stations

When applying GTM900 to a phone-type fixed station, you need a keyboard and LCD.
The external CPU controls the keyboard and LCD.
See Figure 1-4 for the functional architecture of the phone-type fixed station.

Battery charge/
AUDIO
AUDIO discharge and
ANT management

UART
CPU Serial interface
G
T
SIM SIM KEYPAD
M
9
0 IRDA
IRDA LCD
0

ADC Sampling, power-

on/off detection

POWER
POWER

Figure 1-4 Functional architecture of phone-type fixed station

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 1 Overview of GTM900

1.6.3 Application to Vehicle-Mounted Stations and Public Telephones

The application of GTM900 to a vehicle-mounted station or a public telephone is the

same to the above two applications. You may develop the wanted keyboards, LCDs,
and other devices.

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 2 Interface Signals

Chapter 2 Interface Signals

2.1 About This Chapter

This chapter presents the interface signals of GTM900 from the following aspects:
z Interfaces of Signal Connector on GTM900
z Antenna Interface

2.2 Interfaces of Signal Connector on GTM900

2.2.1 Interface Signals

Table 2-1 lists the detailed description of the interface signals of GTM900.

Table 2-1 Interface signals

No. Signal I/O Interface Function Note

level
1 Batt+ I 4.0 V Supplying power --
2 Batt+ I 4.0 V Supplying power --

3 Batt+ I 4.0 V Supplying power --

4 Batt+ I 4.0 V Supplying power --
5 Batt+ I 4.0 V Supplying power --

6 GND O/I -- Providing working ground --

7 GND O/I -- Providing working ground --

8 GND O/I -- Providing working ground --
9 GND O/I -- Providing working ground --
10 GND O/I -- Providing working ground --

11 RXD2 at the O 3.0 V Serial interface for traffic --

infrared control, supporting adaptive
serial rate
interface

12 TXD2 at the I 3.0 V Serial interface for traffic --

infrared control, supporting adaptive
serial rate
interface
13 VDD O -- Signal indication of normally --
started GTM900
14 ADC I -- A/D conversion 10bits
0-3V

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 2 Interface Signals

No. Signal I/O Interface Function Note

level
15 PWON I 3.0 V Power-on control signals --
triggered only at low level

16 UART_DSR O 3.0 V Indicating whether the serial --

interface is ready

17 UART_RI O 3.0 V Ringer indication of the serial --

interface for use as call display
and hang-up indication
18 UART_RXD O 3.0 V Receive signals at PC serial --
interfaces
19 UART_TXD I 3.0 V Transmit signals at PC serial --
interfaces

20 UART_CTS O 3.0 V Receive Request message --

delivered over the PC serial
interface for traffic control
21 UART_RTS I 3.0 V Transmit Ready message --
delivered over the PC serial
interface for traffic control

22 UART_DTR I 3.0 V Signal indication that the PC --

serial interface is ready

23 UART_DCD O 3.0 V Carrier detection --

24 SIM_CD I 3.0V Input signals indicating whether --
the SIM card is configured
25 SIM_RST O 3.0 V Output signals to reset the SIM --
card
26 SIM_DATA I/O 3.0 V Input interface and output --
interface of the SIM card
27 SIM_CLK O 3.0 V Clock signals of the SIM card --
provided by the baseband chip
28 SIM_VCC O 3.0 V Output signals supplying power --
to the SIM card
29 SIM_GND O/I -- Earth signal of SIM card --
30 Vbackup O/I 3.0 V Standby battery of GTM900 --
31 RST I -- Reset signal --
32 LPG O -- Mainly controls the status of the --
indicator.
33 AUXO+ O -- Hands-free audio output --
signals+
34 AUXO- O -- Hands-free audio output --
signals–

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 2 Interface Signals

No. Signal I/O Interface Function Note

level
35 EAR+ O -- Receiver audio output signals+ --
36 EAR- O -- Receiver audio output signals– --
37 MIC+ I -- Receiver audio input signals+ --
38 MIC- I -- Receiver audio input signals– --
39 AUXI+ I -- Hands-free audio input signals+ --
40 AUXI- I -- Hands-free audio input signals– --

Note:
The signals at the serial interfaces are named with PC as the DCE(Data
Communications Equipment).

2.2.2 Design of Signal Connector

The signal connector assembled on GTM900 is a type of 40-pin FPC with the cross-pin
distance of 0.5 mm and the cross-wire distance of 0.5 mm. The connector employs the
single-row and surface-mounted structure with bend pins and the cable-locking device.
It is type Hirose FH12-40S-0.5SH. See Figure 2-1 for its appearance.

Figure 2-1 Appearance of signal connector

2.3 Antenna Interface

GTM900 uses a GSC connector to establish the RF connection to the relevant terminal.
The external antenna connects to the connector through a cable. The connector with

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 2 Interface Signals

the part number of MM9329-2700 is provided by Murata. See the dimensions illustrated
in Figure 2-2.

Figure 2-2 Dimensions of antenna connector (unit: mm)

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 3 Electrical Characteristics of Interfaces

Chapter 3 Electrical Characteristics of Interfaces

3.1 About This Chapter

This chapter presents the electrical characteristics of the interfaces of GTM900 from
the following aspects:
z Absolute Maximum Ratings
z Recommended Operating Conditions
z Power Supply Characteristics

Note:
This chapter focuses on the electrical characteristics of the interfaces on GTM900 for
external services, not including the power supply part.

3.2 Absolute Maximum Ratings

See Table 3-1 for the absolute maximum ratings of GTM900.

Table 3-1 Absolute maximum ratings of GTM900

Parameter Description Min. Max. Unit

Ts Storage temperature –40 +70 °C
Vi Input or output signal voltage on –0.5 3.5 V
any of the pins.

IIN Input current -- 100 mA

VESD Electrostatic voltage -- ±2000 V

Note:
“Vi” in Table 3-1 refers to common I/O pins, not including the power supply pins. The
maximum input voltage of a power supply pin is 4.8 V.

3.3 Recommended Operating Conditions

See Table 3-2 for the recommended operating conditions of GTM900.

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 3 Electrical Characteristics of Interfaces

Table 3-2 Recommended operating conditions of GTM900

Parameter Description Min. Max. Unit

VIH High level input voltage 1.85 3.14 V
VIH Low level input voltage –0.3 0.9 V

IIH Leakage current of high level -- 2 uA

input voltage

IIL Leakage current of low level –2 -- uA

input voltage

VOH High level output voltage 2.39 3.00 V

VOL Low level output voltage 0 0.45 V
CIN Input capacitance -- 15 pF

3.4 Power Supply Characteristics

3.4.1 Input Power

Table 3-3 lists the values for the input power of GTM900.

Table 3-3 Values for input power of GTM900

Parameter Min. Typical Max. Unit

VBatt+ 3.3 4 4.8 V

3.4.2 Operating Current

Table 3-4 lists the values for the operating current of GTM900.

Table 3-4 Values for operating current of GTM900

Operating Parameter Min. Max. Unit

mode
Idle Ireg -- 4.0 mA
Conversation Ireg -- 250 mA

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 4 Interface Application

Chapter 4 Interface Application

4.1 About This Chapter

This chapter presents the application of the interfaces from the following aspects:
z UART Interface
z SIM Interface
z Audio Interface
z Ringer Interface
z Power Supply Interface

4.2 UART Interface

The UART interface realizes serial communications with external devices, supporting
level input and level output at 3.00 V (VDD_MSM_P).
All the signals over the UART interface are triggered at low level except RXD and TXD.
The latter two are triggered at high level.
The UART interface supports both transmit FIFO (First In First Out) and receive FIFO at
512 byte, programmable data width, programmable data stop bit, and programmable
parity check or non check. The maximum rate the UART interface supports is 115.2
kbps. The default rate is 9600 bps.
See Table 4-1 for detailed description of the UART interface signals.

Table 4-1 Signals over UART interface

No. Signal name Description Characteristic Direction

23 UART_DCD Carrier detection Data links already DCE-DTE
connected
17 UART_RI Ringer indication Notifying DTE of DCE-DTE
remote call-in
20 UART_RTS Request transmit DTE sends Request DTE-DCE
transmit message to
DCE

18 UART_TXD Transmit data DTE transmits data DTE-DCE

16 UART_DSR Data services DCE is ready for DCE-DTE
ready data services
22 UART_DTR Data terminal DTE is ready DTE-DCE
ready
21 UART_CTS Clear transmit DCE is switched to DCE-DTE
the Rx mode

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 4 Interface Application

No. Signal name Description Characteristic Direction

19 UART_RXD Receive data DTE receives serial DCE-DTE
data
6 GND GND -- --

For the output signals, GTM900 can be directly connected to an external drive device
operating at 3.3 V. If the input signals exceed the value range of GTM900, they must
undergo level alignment.

4.3 SIM Interface

GTM900 can be connected to an external SIM card operating at 3.0 V. See Table 4-2
for the signals over the SIM interface.

Table 4-2 Signals over SIM interface

No. Signal name Description

27 SIM_CLK Clock signals over the SIM interface

25 SIM_RST Reset signals over the SIM interface

26 SIM_DATA Data lines of the SIM card
28 SIM_VCC Power supply to the SIM card

24 SIM_CD SIM card configured

29 SIM_GND SIM card grounded

4.4 Audio Interface

GTM900 supports two channels of audio input signals and audio output signals. The
two types of signals are both differential ones. In practice, you may use one channel or
both. See Figure 4-1 and Table 4-2 for the two channels of input signals and output
signals.

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 4 Interface Application

Figure 4-1 Connection between audio input signals and output signals on first channel

Figure 4-2 Connection between audio input signals and output signals on second
channel

Note:
The maximum power of the audio signals output to the 32 Ω loudspeaker on the first
channel is 33 mW, and that of the audio signals output to the 1 kΩ loudspeaker on the
second channel is 4 mW.

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 4 Interface Application

See Table 4-3 for the signals over the Audio interface.

Table 4-3 Signals over Audio interface

No. Signal name Description

33 AUXO+ Handsfree audio output signal+
34 AUXO- Handsfree audio output signal

39 AUXI+ Handsfree audio input signal+

40 AUXI- Handsfree audio input signal

35 EAR+ Handheld audio output signal+

36 EAR- Handheld audio output signal

37 MIC+ Handheld audio input signal+

38 MIC- Handheld audio input signal

4.5 Ringer Interface

If you drive an external ringer with the Ringer signals, you shall need an external drive
circuit. See Figure 4-3 for the drive circuit of the Ringer signals.

Figure 4-3 Drive circuit of Ringer signals

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 4 Interface Application

4.6 Power Supply Interface

The external power supply to GTM900 is 4.0 V. In practice, the voltage range can be
from 3.3 V to 4.8 V.

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 5 Operating Process

Chapter 5 Operating Process

5.1 About This Chapter

This chapter presents the operating process of GTM900 from the following aspects:
z Powering on/off GTM900
z Software Upgrade of GTM900
z Data Services
z Services Presentation Diagram of GTM900

5.2 Powering on/off GTM900

5.2.1 Powering UP GTM900

When the power supply to GTM900 is higher than 3.3 V and the PWON signal is low
level, GTM900 operates as illustrated in Figure 5-1.

4.0 V
3.3 V

VBATT+

PWON

2.8 V

VDD

Figure 5-1 Relationship between VDD and PWON signal

5.2.2 Powering Down GTM900

GTM900 might be powered down in the two cases below:

I. Powering down GTM900 normally

During normal powering down of GTM900, the external CPU lowers the level of PWON
signal level for 2 to 3 seconds to put GTM900 into normal powering down procedure. In
this case, GTM900 can save relevant information and completes network
deregistration.

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 5 Operating Process

II. Powering down GTM900 in emergencies

Through AT commands, the external CPU powers off GTM900 directly.

5.3 Software Upgrade of GTM900

GTM900 supports software upgrade. You may upgrade the software of GTM900 over
the serial interface. For detailed operations, see the operation manual.

5.4 Data Services of GTM900

The data services provided by GTM900 are transmitted over the serial interface. See
Figure 5-2 for the network access of GTM900.

DL data at 38.4 kbps

G
Serial T
External interface M
PC
CPU 9
0
Interface
board 0

UL data at 9.6 kbps

Figure 5-2 Data services of GTM900

For the downlink data,

z GTM900 transmits the data received from the network to the external CPU over
the serial interface.
z The CPU then forwards the data to external data terminals, for example,
computers.
For the uplink data, the process is similar. However, when providing data services,
GTM900 does not process other AT commands delivered by external equipment.

5.5 Services Presentation Diagram of GTM900

See Figure 5-3 for the services presentation diagram of GTM900.

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 5 Operating Process

50 ohm cable or
Standard antenna to system
RS232 3 V level signal simulator
serial requiring level GSC RF
interface conversion cable
GSM
40-PIN
flexible applications
(fixed station,
PC GTM900 cable
vehicle-mounted
station, and
mobile station)

SIM

Power
supply
UE

Figure 5-3 Functionality of GTM900

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 6 Acronyms and Abbreviations

Chapter 6 Acronyms and Abbreviations

ADC Analog-to-Digital Converter

AFC Automatic Frequency Control
AGC Automatic Gain Control
ARFCN Absolute Radio Frequency Channel Number
ARP Antenna Reference Point
BER Bit Error Rate
BTS Base Transceiver Station
CS Coding Scheme
CSD Circuit Switched Data
CE Conformité Européene (European Conformity)
DSP Digital Signal Processor
DTR Data Terminal Ready
DTX Discontinuous Transmission
EFR Enhanced Full Rate
EMC Electromagnetic Compatibility
ESD Electrostatic Discharge
GMSK Gaussian Minimum Shift Keying
GPRS General Packet Radio Service
HiZ High Impedance
HR Half Rate
IMEI International Mobile Equipment Identity
FDMA Frequency Division Multiple Access
ISO International Standards Organization
ITU International Telecommunications Union
LED Light Emitting Diode
MO Mobile Originated
MMI Man Machine Interface
MT Mobile Terminated
NTC Negative Temperature Coefficient
PDU Protocol Data Unit

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Huawei GTM900 GSM/GPRS Wireless Module Chapter 6 Acronyms and Abbreviations

PPP Point-to-point protocol

RAM Random Access Memory
SAR Specific Absorption Rate
SELV Safety Extra Low Voltage
UART Universal asynchronous receiver-transmitter
ZIF Zero Insertion Force
VSWR Voltage Standing Wave Ratio

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