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 37 of 125 17.12.2004
3.3.3 Automatic shutdown
Automatic shutdown takes effect if
• the XT55/56 board is exceeding the critical limits of overtemperature or undertemperature
• the battery is exceeding the critical limits of overtemperature or undertemperature
• undervoltage is detected
The automatic shutdown procedure is equivalent to the power-down initiated with the
AT^SMSO command, i.e. XT55/56 logs off from the network and the software enters a
secure state avoiding loss of data. NOTE: This does not apply if overvoltage conditions or
unrecoverable hardware or software errors occur (see below for details).
Alert messages transmitted before the device switches off are implemented as Unsolicited
Result Codes (URCs). The presentation of these URCs can be enabled or disabled with the
two AT commands AT^SBC and AT^SCTM. The URC presentation mode varies with the
condition, please see Chapters 3.3.3.1 to 3.3.3.4 for details. For further instructions on AT
commands refer to [1].
3.3.3.1 Temperature dependent shutdown
The board temperature is constantly monitored by an internal NTC resistor located on the
PCB. The NTC that detects the battery temperature must be part of the battery pack circuit
as described in Chapter 3.5. The values detected by either NTC resistor are measured
directly on the board or the battery and therefore, are not fully identical with the ambient
temperature.
Each time the board or battery temperature goes out of range or back to normal, XT55/56
instantly displays an alert (if enabled).
• URCs indicating the level "1" or "-1" allow the user to take appropriate precautions, such
as protecting the module from exposure to extreme conditions. The presentation of the
URCs depends on the settings selected with the AT^SCTM write command:
AT^SCTM=1: Presentation of URCs is always enabled.
AT^SCTM=0 (default): Presentation of URCs is enabled for 15 seconds time after
start-up of XT55/56. After 15 seconds operation, the presentation will be disabled, i.e.
no alert messages can be generated.
• URCs indicating the level "2" or "-2" are instantly followed by an orderly shutdown. The
presentation of these URCs is always enabled, i.e. they will be output even though the
factory setting AT^SCTM=0 was never changed.
The maximum temperature ratings are stated in Table 26. Refer to Table 6 for the associated
URCs. All statements are based on test conditions according to IEC 60068-2-2 (still air).