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 36 of 125 17.12.2004
3.3.2.2 Emergency shutdown using GSM_EMERGOFF pin
Caution: Use the GSM_EMERGOFF pin only when, due to serious problems, the
software is not responding for more than 5 seconds. Pulling the
GSM_EMERGOFF pin causes the loss of all information stored in the volatile
memory since power is cut off immediately. Therefore, this procedure is
intended only for use in case of emergency, e.g. if XT55/56 fails to shut down
properly.
The GSM_EMERGOFF signal is available on the board-to-board connector. To control the
GSM_EMERGOFF line it is recommended to use an open drain / collector driver. To turn the
GSM engine off, the GSM_EMERGOFF line has to be driven to ground for ≥ 3.2s.
Figure 6: Deactivating GSM engine by GSM_EMERGOFF signal
GSM_BATT+
Internal reset
GSM_EMERGOFF
Controlled by external
application
max. 3.2s
GSM_IGT
GSM_VDD
How does it work:
• Voltage V
GSM_BATT+
is
permanently applied to the
module.
• The module is active while
the internal reset signal is
kept at high level.
During operation of XT55
the baseband controller
generates watchdog pulses
at regular intervals.
Once the GSM_EMERGOFF
pin is grounded these
watchdog pulses are cut off
from the power supply ASIC.
The power supply ASIC
shuts down the internal
supply voltages of XT55
after max. 3.2s and the
module turns off.
Consequently, the output
voltage at GSM_VDD is
switched off.
Controlled by
XT55 software