User Manual

MC45 Hardware Interface Description
P R E L I M I N A R Y
MC45_HD_01_V00.02a Page 40 of 90 12.08.2002
3.3.3 Turn off MC45
To switch the module off the following procedures may be used:
· Normal shutdown procedure: Software controlled by sending the AT^SMSO command
over the RS-232 application interface. See Chapter 3.3.3.1.
· Emergency shutdown: Hardware driven by switching the /EMERGOFF line of the board-
to-board connector to ground = immediate shutdown of supply voltages, only applicable
if the software controlled procedure fails! See Chapter 3.3.3.2.
· Automatic shutdown: Takes effect if undervoltage / overvoltage is detected or if battery
or board (engine) temperature exceeds critical limit. See Chapter 3.3.4.
3.3.3.1 Turn off MC45 using AT command
The best and safest approach to powering down MC45 is to issue the AT^SMSO command.
This procedure lets MC45 log off from the network and allows the software to enter into a
secure state and safe data before disconnecting the power supply.
Before switching off the device sends the result code
^SMSO: MS is OFF
From this moment on, no further AT commands can be executed. Only the RTC is still
active. The mode is referred to as POWER DOWN mode.
While MC45 is in POWER DOWN mode the application interface is switched off and must
not be fed from any other source. Therefore, your application must be designed to avoid any
current flow into any digital pins of the application interface. POWER DOWN is also
signalized by the VDD pin, which in this mode, is off.