User's Manual

AC65/AC75 Hardware Interface Description
Confidential / Preliminary
s
AC65/AC75_hd_v00.372 Page 31 of 118 2006-08-03
3.3.1.2 Configuring the IGT Line for Use as ON/OFF Switch
The IGT line can be configured for use in two different switching modes: You can set the IGT
line to switch on the module only, or to switch it on and off. The switching mode is
determined by the parameter “MEShutdown/OnIgnition” of the AT^SCFG command. This
approach is useful for application manufacturers who wish to have an ON/OFF switch
installed on the host device.
By factory default, the ON/OFF switch mode of IGT is disabled:
at^scfg=meshutdown/onignition
^SCFG: "MEShutdown/OnIgnition","off"
OK
# Query the current status of IGT.
# IGT can be used only to switch on
AC65/AC75.
IGT works as described in Section 3.3.1.1.
To configure IGT for use as ON/OFF switch:
at^scfg=meshutdown/onignition,on
^SCFG: "MEShutdown/OnIgnition","on"
OK
# Enable the ON/OFF switch mode of IGT.
# IGT can be used to switch on and off
AC65/AC75.
We strongly recommend taking great care before changing the switching mode of the IGT
line. To ensure that the IGT line works properly as ON/OFF switch it is of vital importance
that the following conditions are met.
Switch-on condition: If the AC65/AC75 is off, the IGT line must be asserted for at least
400ms before being released. The module switches on after 400ms.
Switch-off condition: If the AC65/AC75 is on, the IGT line must be asserted for at least 1s
before being released. The module switches off after the line is
released.
The switch-off routine is identical with the procedure initiated by
AT^SMSO, i.e. the software performs an orderly shutdown as
described in Section 3.3.3.1.
Before switching off the module wait at least 2 seconds after startup.
ON OFF
~~~~
|________|
~~~~~~~~~~~~~
|________|
~~~~
| 0.4s |  2s |  1s |
Figure 7: Timing of IGT if used as ON/OFF switch