SIM Tech SimCom SIM340, Проектирование аппаратного обеспечения

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SIM340 Hardware Design
will return 0 which indicates that the protocol stack is closed. Then after 90s, SIM340 will power
down automatically. However, during alarm mode, if the software protocol is started by
AT+CFUN=1 command, the process of automatic power down will not be available. In alarm
mode, driving the PWRKEY to a low level voltage for a period will cause SIM340 to be powered
down (Please refer to the power down scenario).
The table follow briefly summarizes the AT commands that are used usually during alarm mode,
for details of the instructions refer to
document [1]
:
Table
7
: AT commands used in Alarm mode
AT command Use
AT+CALARM Set alarm time
AT+CCLK Set data and time of RTC
AT+CPOWD Power down
AT+CFUN Start or close the protocol stack
3.4.2 Turn off SIM340
Following procedure can be used to turn off the SIM340:
Normal power down procedure: Turn off SIM340 using the PWRKEY pin
Normal power down procedure: Turn off SIM340 using AT command
Over-voltage or under-voltage automatic shutdown: Take effect if over-voltage or under-voltage is
detected
Over-temperature or under-temperature automatic shutdown: Take effect if over-temperature or
under-temperature is detected
3.4.2.1 Turn off SIM340 using the PWRKEY pin (Power down)
You can turn off the SIM340 by driving the PWRKEY to a low level voltage for some time. Please
refer to the turn on circuit. The power down scenario illustrates as following figure.
This procedure lets the module log off from the network and allow the software to enter into a
secure state and save data before completely disconnect the power supply.
Before the completion of the switching off procedure the module will send out result code:
NORMAL POWER DOWN
After this moment, the AT commands can’t be executed. The module enters the POWER DOWN
mode, only the RTC is still active. POWER DOWN can also be indicated by VDD_EXT pin,
which is a low level voltage in this mode.
SIM340_HD_V3.09 18.03.2009
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