Smart Machine Smart Decision
4.2.2
Power down SIM808
SIM808 will be powered down in the following situations
：
z
Normal power down procedure: power down SIM808 by the PWRKEY pin.
z
Normal power down procedure: power down SIM808 by AT command “AT+CPOWD=1”.
z
Abnormal power down: over-voltage or under-voltage automatic power down.
z
Abnormal power down: over-temperature or under-temperature automatic power down.
NOTE
：
The VBUS pin should not be charged, otherwise ,the module will not be powered down.
4.2.2.1
Power down SIM808 by the PWRKEY Pin
User can power down SIM808 by pulling down the PWRKEY pin for at least 1 second and release. Please refer to
the power on circuit. The power down scenario is illustrated in following figure.
Figure 14: Timing of power down SIM808 by PWRKEY
This procedure makes the module log off from the network and allows the software to enter into a secure state to
save data before completely shut down.
Before the completion of the power down procedure, the module will send URC:
NORMAL POWER DOWN
At this moment, AT commands can not be executed any more, and only the RTC is still active. Power down mode
can also be indicated by STATUS pin, which is at low level at this time.
4.2.2.2
Power down SIM808 by AT Command
SIM808 can be powered down by AT command “AT+CPOWD=1”. This procedure makes the module log off
from the network and allows the software to enter into a secure state to save data before completely shut down.
Before the completion of the power down procedure, the module will send URC:
NORMAL POWER DOWN
At this moment, AT commands can not be executed any more, and only the RTC is still active. Power down mode
can also be indicated by STATUS pin, which is at low level at this time.
SIM808_Hardware Design_V1.00 2014.03.27
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