User's Manual
Table Of Contents
- Contents
- Figures
- Tables
- Document history
- Introduction
- Product concept
- GSM application interface
- GSM/GPRS operating modes
- Power supply
- Power up / down scenarios
- Automatic GPRS Multislot Class change
- Charging control of the GSM part
- Power saving
- Summary of state transitions (except SLEEP mode)
- RTC backup for GSM part of XT55/56
- Serial interfaces of the XT55/56 GSM part
- Audio interfaces
- SIM interface
- Control signals
- GPS application interface
- GSM and GPS antenna interfaces
- Electrical, reliability and radio characteristics
- Mechanics
- Reference approval
- Example applications
- List of parts and accessories
XT55/56 Hardware Interface Description
Confidential / Released
s
XT55/56_hd_v02.06a Page 75 of 125 17.12.2004
4.4 Power supply of the XT55/56 GPS part
The power supply for the GPS part of the XT55/56 module has to be a single voltage source
of V
CC
=3.3V ± 5%. It must be able to provide sufficient current of >100mA.
GPS_VCC:
Two GPS_VCC pins of the board-to-board connector are dedicated to connect the power
supply voltage, five GND pins shared with the GSM part of the XT55/56 module are
recommended for grounding; see Figure 40 for details.
If no GPS_VCC is connected to XT55/56, the RTC and SRAM of the GPS part of XT55/56
can be fed by GSM_BATT+ of XT55/56.
GPS_VANT:
This pin is used for an external DC power supply of an active antenna.
The GPS_VANT input voltage should be chosen according to the connected antenna.
In order to use a 5V active GPS antenna, the GPS_VANT has to be connected to 5V
external power supply.
When using a 3V antenna it is possible to connect the GPS_VCC_RF output (which provides
3.0V) to GPS_VANT.
GPS_VCC_RF:
This pin is an output which provides +3.0V DC and can be connected to the GPS_VANT in
order to supply the GPS antenna.
In Trickle Power mode and Push-to-Fix mode, GPS_VCC_RF is switched off during the
sleep phase.
GSM_BATT+:
If no GPS_VCC is connected to XT55/56, the RTC and SRAM of the GPS part of XT55/56 is
fed by GSM_BATT+ of XT55/56.
4.5 General purpose input/output
Several I/O’s (GPS_GPIO0, GPS_GPIO1, GPS_GPIO3, GPS_GPIO5, GPS_GPIO6,
GPS_GPIO7, GPS_GPIO10, GPS_GPIO13, GPS_GPIO14, GPS_GPIO15) of the CPU are
connected to the hardware interface connector of the XT55/56 GPS receiver. They are
reserved for customer specific applications.
NOTE: Not all of these pins are supported by the current GPS firmware.