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AC75 Hardware Interface Description
Strictly confidential / Preliminary
3.3.1.5
Reset or Turn off AC75 in Case of Emergency
Caution: Use the EMERG_RST pin only when, due to serious problems, the software is not
responding for more than 5 seconds. Pulling the EMERG_RST pin causes the loss of all
information stored in the volatile memory. Therefore, this procedure is intended only for use
in case of emergency, e.g. if AC75 does not respond, if reset or shutdown via AT command
fails.
The EMERG_RST signal is available on the application interface. To control the
EMERG_RST line it is recommended to use an open drain / collector driver.
The EMERG_RST line can be used to switch off or to reset the module. In any case the
EMERG_RST line must be pulled to ground for ≥10ms. Then, after releasing the
EMERG_RST line the module restarts if IGT is held low for at least 400ms. Otherwise, if IGT
is not low the module switches off. In this case, it can be restarted any time as described in
section 3.3.1.1.
After hardware driven restart, notification via "^SYSSTART" or "^SYSSTART AIRPLANE"
URC is the same as in case of restart by IGT or AT command. To register to the network SIM
PIN authentication is necessary after restart.
3.3.1.6
Using EMERG_RST Signal to Reset Application(s) or External
Device(s)
When the module starts up, while IGT is held low for 400ms, the EMERG_RST signal goes
low for 120ms as shown in Figure 5 and Figure 6. During this 120ms period, EMERG_RST
becomes an output which can be used to reset application(s) or external device(s) connected
to the module.
After the 120ms period, i.e. during operation of the module, the EMERG_RST is an input.
Specifications of the input and output mode of EMERG_RST can be found in Table 26.
AC75_HD_V00.202
Page 31 of 120
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27.04.2006
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