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Java Terminals Hardware Interface Description
3.9 Automatic thermal shutdown
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EHSxT_BGS5T_HID_v02 2014-05-23
Confidential / Preliminary
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3.9 Automatic thermal shutdown
An on-board NTC measures the temperature of the built-in BGS2 module. If over- or undertem-
perature is detected on the module the Java Terminals automatically shut down to avoid ther-
mal damage to the system.
Table 17 specifies the ambient temperature threshold for the Java
Terminals.
The automatic shutdown procedure is equivalent to the power-down initiated with the
AT^SMSO command, i.e. Java Terminals log off from the network and the software enters a
secure state avoiding loss of data. In IDLE mode it takes typically one minute to deregister from
the network and to switch off.
Alert messages transmitted before the Java Terminals switch off are implemented as Unsolic-
ited Result codes (URCs). For details see the description of AT^SCTM command provided in
[1] .
Thermal shutdown will be deferred if a critical temperature limit is exceeded, while an emer-
gency call or a call to a predefined phone number is in progress, or during a two minute guard
period after power up. See
[1] for details.
The watchdog can be configured to restart the Java Terminals after a defined period.
3.10 Hardware Watchdog
The Java Terminals feature a programmable hardware watchdog that permanently monitors
the terminals‘ hardware and can be configured to react to various hardware states. The watch-
dog may for example be configured to periodically restart the terminal, independant of its cur-
rent operating state.
Figure 4 shows how the watchdog is integrated into the Java Terminals.
Please refer to Chapter 8 for details on how to control and configure the hardware watchdog.
3.11 RTC
The internal Real Time Clock (RTC) of the Java Terminals retains the time and date and han-
dles the alarm (reminder) function. The AT+CCLK command serves to set the time and date,
and AT+CALA specifies a reminder message. See
[1] for details.
A dedicated voltage regulator backs up the RTC even in Power Down mode and enables Java
Terminals to keep track of time and date.
However, please note that the Alarm mode described in [1] , Section AT+CALA, is not intended
for the Java Terminals. The AT+CALA command can only be used to set a reminder message,
but not to configure the mobile to wake up from POWER DOWN mode into Alarm mode. There-
fore, after setting a timer with AT+CALA be sure not to shut down the Java Terminals by
AT^SMSO or RST_IN signal.