Telit Wireless Solutions GC864 Series Installation manual

GC864 Hardware User Guide
GC864-PY, GC864-QUAD
1vv0300733 Rev. 0 - 12/06/06

GC864 Hardware User Guide
1vv0300733 Rev. 0 - 12/06/06
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Right reserved page 2 of 68
Contents
1Overview ...........................................................................................................................4
2Hardware Commands ......................................................................................................5
2.1 Turning ON the GC864 ...........................................................................................................5
2.2 Turning OFF the GC864 ........................................................................................................7
2.2.1 Hardware shutdown..........................................................................................................................7
2.3 Hardware Unconditional Reboot...........................................................................................7
3Power Supply ...................................................................................................................9
3.1 Power Supply Requirements.................................................................................................9
3.2 General Design Rules ..........................................................................................................10
3.2.1 Electrical design Guidelines........................................................................................................... 10
3.2.1.1 + 5V input Source Power Supply Design Guidelines ................................................................ 10
3.2.1.2 + 12V input Source Power Supply Design Guidelines .............................................................. 12
3.2.1.3 Battery Source Power Supply Design Guidelines ..................................................................... 13
3.2.1.4 Battery Charge control Circuitry Design Guidelines .................................................................. 13
3.2.2 Thermal Design Guidelines ........................................................................................................... 15
3.2.3 Power Supply PCB layout Guidelines ........................................................................................... 16
4Antenna...........................................................................................................................17
4.1 Antenna Requirements ........................................................................................................17
4.2 GC864 Antenna Connector..................................................................................................17
4.3 Antenna installation Guidelines..........................................................................................18
5GC864 pins allocation....................................................................................................19
NOTE: RESERVED pins must not be connected..........................................................................21
6Serial Port .......................................................................................................................22
6.1 RS232 level translation ........................................................................................................24
6.2 5V UART level translation....................................................................................................26
7Audio Section Overview ................................................................................................28
7.1 Microphone paths characteristic and requirements .........................................................30
7.2 General Design Rules ..........................................................................................................33
7.3 Other considerations. ..........................................................................................................33
7.4 Microphone Biasing .............................................................................................................34
7.4.1 Balanced Microphone biasing........................................................................................................ 34
7.4.2 Unbalanced Microphone biasing ...................................................................................................35

GC864 Hardware User Guide
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7.5 Microphone buffering...........................................................................................................37
7.5.1 Buffered Balanced Mic................................................................................................................... 37
7.5.2 Buffered Unbalanced (Single Ended) Microphone . ...................................................................... 39
8OUTPUT LINES (Speaker)..............................................................................................42
8.1 Short description..................................................................................................................42
8.2 Output lines characteristics . .............................................................................................43
8.3 General Design rules............................................................................................................44
8.3.1 Noise Filtering................................................................................................................................ 44
8.4 Handset earphone design....................................................................................................45
8.5 Hands-free earphone (low power) design ..........................................................................46
8.6 Car Kit speakerphone design..............................................................................................47
9External SIM Holder .......................................................................................................48
9.1 SIM DESIGN GUIDES............................................................................................................48
10 General Purpose I/O.......................................................................................................50
10.1 Using a GPIO pad as INPUT.............................................................................................50
10.2 Using a GPIO pad as OUTPUT.........................................................................................50
10.3 Using the Alarm Output GPIO_06/ALARM......................................................................51
10.4 Using the Buzzer Output GPIO_07/BUZZER...................................................................51
11 Camera ............................................................................................................................52
11.1 Camera characteristics ....................................................................................................52
11.1.1 Camera interface connectors......................................................................................................... 52
11.1.2............................................................................................................................................................. 53
11.1.3............................................................................................................................................................. 53
11.1.4............................................................................................................................................................. 53
11.1.5 EVB for Transchip camera support ............................................................................................... 54
11.1.6 Example usage script for camera .................................................................................................. 55
12 Conformity Assessment Issues....................................................................................56
13 SAFETY RECOMMANDATIONS.....................................................................................57
14 Document Change Log ..................................................................................................58
Annex A – EVK2 schematics ...............................................................................................59
Annex B - Camera EVB schematics ....................................................................................65

GC864 Hardware User Guide
1vv0300733 Rev. 0 - 12/06/06
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Right reserved page 4 of 68
1 Overview
The aim of this document is the description of some hardware solutions useful for developing a product with the
Telit GC864 module.
In this document all the basic functions of a mobile phone will be taken into account; for each one of them a
proper hardware solution will be suggested and eventually the wrong solutions and common errors to be
avoided will be evidenced. Obviously this document can not embrace the whole hardware solutions and
products that may be designed. The wrong solutions to be avoided shall be considered as mandatory, while the
suggested hardware configurations shall not be considered mandatory, instead the information given shall be
used as a guide and a starting point for properly developing your product with the Telit GC864 module. For
further hardware details that may not be explained in this document refer to the Telit GC864 Product Description
document where all the hardware information is reported.
NOTICE
(EN) The integration of the GC864 GSM/GPRS cellular module within user application shall be
done according to the design rules described in this manual.
(IT) L’integrazione del modulo cellulare GSM/GPRS GC864 all’interno dell’applicazione
dell’utente dovrà rispettare le indicazioni progettuali descritte in questo manuale.
(DE) Die Integration des GC864 GSM/GPRS Mobilfunk-Moduls in ein Gerät muß gemäß der in
diesem Dokument beschriebenen Konstruktionsregeln erfolgen
(SL) Integracija GSM/GPRS GC864 modula v uporabniški aplikaciji bo morala upoštevati
projektna navodila, opisana v tem priročniku.
(SP) La utilización del modulo GSM/GPRS GC864 debe ser conforme a los usos para los
cuales ha sido diseñado descritos en este manual del usuario
(FR) L'intégration du module cellulaire GC864 GSM/GPRS dans l'application de l'utilisateur
sera faite selon les règles de conception décrites dans ce manuel
(HE)
The information presented in this document is believed to be accurate and reliable. However, Telit
Communication assumes no responsibility for its use, nor any infringement of patents or other rights of third
parties which may result from its use. No license is granted by implication or otherwise under any patent rights of
Telit Communication other than for circuitry embodied in Telit products. This document is subject to change
without notice.

GC864 Hardware User Guide
1vv0300733 Rev. 0 - 12/06/06
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Right reserved page 5 of 68
2 Hardware Commands
2.1 Turning ON the GC864
To turn on the GC864 the pad ON# must be tied low for at least 1 second and then released.
The maximum current that can be drained from the ON# pad is 0,1 mA.
A simple circuit to do it is:
NOTE: don't use any pull up resistor on the ON# line, it is internally pulled up. Using pull up
resistor may bring to latch up problems on the GC864 power regulator and improper power
on/off of the module. The line ON# must be connected only in open collector configuration.
NOTE: In this document all the lines that are inverted, hence have active low signals are
labeled with a name that ends with a "#" or with a bar over the name.
NOTE: The GC864 turns fully on also by supplying power to the Charge pad (provided there's
a battery on the VBATT pads).
ON#
Power ON impulse
GND
R1
R2
Q1

GC864 Hardware User Guide
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For example:
1- Let's assume you need to drive the ON# pad with a totem pole output of a +3/5 V microcontroller
(uP_OUT1):
2- Let's assume you need to drive the ON# pad directly with an ON/OFF button:

GC864 Hardware User Guide
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Reproduction forbidden without Telit Communications S.p.A. written authorization - All Right reserved page 7 of 68
2.2 Turning OFF the GC864
The turning off of the device can be done in three ways:
• by software command (see GC864 Software User Guide)
• by hardware shutdown
When the device is shut down by software command or by hardware shutdown, it issues to the
network a detach request that informs the network that the device will not be reachable any more.
2.2.1 Hardware shutdown
To turn OFF the GC864 the pad ON# must be tied low for at least 1 second and then released.
The same circuitry and timing for the power on shall be used.
The device shuts down after the release of the ON# pad.
TIP: To check if the device has powered off, the hardware line PWRCTL should be monitored.
When PWRCTL goes low, the device has powered off.
2.3 Hardware Unconditional Reboot
To unconditionally Reboot the GC864, the pad RESET# must be tied low for at least 200 milliseconds
and then released.
The maximum current that can be drained from the ON# pad is 0,15 mA.
A simple circuit to do it is:
NOTE: don't use any pull up resistor on the RESET# line nor any totem pole digital output.
Using pull up resistor may bring to latch up problems on the GC864 power regulator and
improper functioning of the module. The line RESET# must be connected only in open
collector configuration.
RESET#
Unconditional Reboot
impulse
GND

GC864 Hardware User Guide
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TIP: The unconditional hardware reboot should be always implemented on the boards and
software should use it as an emergency exit procedure.
For example:
1- Let's assume you need to drive the RESET# pad with a totem pole output of a +3/5 V
microcontroller (uP_OUT2):

GC864 Hardware User Guide
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Reproduction forbidden without Telit Communications S.p.A. written authorization - All Right reserved page 9 of 68
3 Power Supply
The power supply circuitry and board layout are a very important part in the full product design and
they strongly reflect on the product overall performances, hence read carefully the requirements and
the guidelines that will follow for a proper design.
3.1 Power Supply Requirements
The GC864 power requirements are:
• Nominal Supply Voltage: 3.8 V
• Max Supply Voltage: 4.2 V
• Supply voltage range: 3.4 V - 4.2 V
• Max Peak current consumption (impulsive): 1.9 A
• Max Average current consumption during GPRS transmission (rms): 500 mA
• Max Average current consumption during VOICE/CSD transmission (rms): 270 mA
• Average current during Power Saving: ≈4 mA
• Average current during idle (Power Saving disabled) ≈19 mA
The GSM system is made in a way that the RF transmission is not continuous, else it is packed into
bursts at a base frequency of about 216 Hz, the relative current peaks can be as high as about 2A.
Therefore the power supply has to be designed in order to withstand with these current peaks without
big voltage drops; this means that both the electrical design and the board layout must be designed for
this current flow.
If the layout of the PCB is not well designed a strong noise floor is generated on the ground and the
supply; this will reflect on all the audio paths producing an audible annoying noise at 216 Hz; if the
voltage drop during the peak current absorption is too much, then the device may even shutdown as a
consequence of the supply voltage drop.
TIP: The electrical design for the Power supply should be made ensuring it will be capable of a
peak current output of at least 2 A.

GC864 Hardware User Guide
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Reproduction forbidden without Telit Communications S.p.A. written authorization - All Right reserved page 10 of 68
3.2 General Design Rules
The principal guidelines for the Power Supply Design embrace three different design steps:
- the electrical design
- the thermal design.
- the PCB layout.
3.2.1 Electrical design Guidelines
The electrical design of the power supply depends strongly from the power source where this power is
drained. We will distinguish them into three categories:
• +5V input (typically PC internal regulator output)
• +12V input (typically automotive)
• Battery
3.2.1.1 + 5V input Source Power Supply Design Guidelines
• The desired output for the power supply is 3.8V, hence there's not a big difference between the
input source and the desired output and a linear regulator can be used. A switching power supply
will not be suited because of the low drop out requirements.
• When using a linear regulator, a proper heat sink shall be provided in order to dissipate the power
generated.
• A Bypass low ESR capacitor of adequate capacity must be provided in order to cut the current
absorption peaks close to the GC864, a 100μF tantalum capacitor is usually suited.
• Make sure the low ESR capacitor on the power supply output (usually a tantalum one) is rated at
least 10V.
• A protection diode should be inserted close to the power input, in order to save the GC864 from
power polarity inversion.