Siemens AC75 Specifications download pdf (Page 31)

AC75 Hardware Interface Description

Strictly confidential / Preliminary

AC75_HD_V00.202 Page 31 of 120 27.04.2006

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.

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Siemens AC75 Specifications Page 31