I65/I56I HARDWARE DESCRIPTION VERSION
1.00
Normal shutdown procedure
: Software controlled by sending the
AT^SMSO
command over the serial application interface. See chapter
Emergency shutdown
: Hardware driven by switching the RESET line
(Pin 26) of the board-to-board connector to ground = immediate
shutdown of supply voltages.
Automatic shutdown
: See chapter
a) Takes effect if under voltage is detected.
b) Takes effect if I56/I56i board temperature exceeds critical limit.
5.4.3.5 Turn off GSM/GPRS engine of the I56/I56i module using AT command
The best and safest approach to powering down the I56/I56i GSM/GPRS
engine is to issue the
AT^SMSO
command. This procedure lets GSM engine
log off from the network and allows the software to enter into a secure state
and safe data before disconnecting the power supply. The mode is referred to
as POWER DOWN mode. In this mode, only the RTC stays active.
Before switching off the device sends the following response:
^SMSO: MS OFF
OK
^SHUTDOWN
After sending
AT^SMSO
do not enter any other AT commands. There are two
ways to verify when the module turns off:
Wait for the URC “SHUTDOWN”. It indicates that data have been
stored non-volatile and the module turns off in less than 1 second.
Be sure not to disconnect the operating voltage V
VC5+
before the URC
“SHUTDOWN” has been issued. Otherwise you run the risk of losing data.
While the GSM engine 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.
Note
: In POWER DOWN mode, the output pins of the ASC0 interface RX_0,
CTS_0, DCD_0, DSR_0, RING_0 are switched to high impedance
state.
If this causes the associated input pins of your application to float, you
are advised to integrate an additional resistor (100 k
Ω
, 1 M
Ω
) at each
line. In the case of the serial interface pins you can either connect pull-
up resistors to an external power source (V
min
< 2.2 and V
max
= 3.3 V,
I
max
= 10 mA), or pull down resistors to GND.
5.4.3.6 Maximum number of turn-on/turn-off cycles
Each time the module is shut down, data will be written from volatile memory
to flash memory. The guaranteed maximum number of write cycles is limited
to 100.000.
5.4.3.7 Emergency shutdown using RESET line
!!!Caution:
Use the RESET pin only when, due to serious problems, the
software is not responding for more than 5 seconds. Pulling the
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