User Manual
Table Of Contents
- 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 / Preliminary
s
XT55/56_hd_v02.96 Page 67 of 125 18.08.2005
3.12.2 Outputs
3.12.2.1 Synchronization Signal
The synchronization signal serves to indicate growing power consumption during the transmit
burst. The signal is generated by the GSM_SYNC pin. Please note that this pin can adopt
two different operating modes which you can select by using the AT^SSYNC command
(mode 0 and 1). For details refer to the following chapter and to [1].
To generate the synchronization signal the pin needs to be configured to mode 0 (= default).
This setting is recommended if you want your application to use the synchronization signal
for better power supply control. Your platform design must be such that the incoming signal
accommodates sufficient power supply to the XT55/56 module if required. This can be
achieved by lowering the current drawn from other components installed in your application.
The timing of the synchronization signal is shown below. High level of the GSM_SYNC pin
indicates increased power consumption during transmission.
Figure 22: GSM_SYNC signal during transmit burst
*)
The duration of the GSM_SYNC signal is always equal, no matter whether the traffic or
the access burst are active.
Transmit burst
1 Tx 577 µs every 4.616 ms
2 Tx 1154 µs every 4.616 ms
300 µs
GSM_SYNC signal
*)