Power Down Sim900D; Power Down Sim900D By The Pwrkey Pin; Power Down Sim900D By At Command - SimCom SIM900D Hardware Design

(please refer to Figure 13 Timing of power on module), the SIM900D will power up and go into Charge mode
during normal operation. In this case, SIM900D sends out result code as following:
From CHARGE-ONLY MODE to NORMAL MODE
In Charge mode during normal operation, all operations and AT commands are available.
4.2.2

Power down SIM900D

SIM900D will be powered down in the following situations：
Normal power down procedure: power down SIM900D by the PWRKEY pin.
Normal power down procedure: power down SIM900D by AT command "AT+CPOWD=1".
Abnormal power down: over-voltage or under-voltage automatic power down.
Abnormal power down: over-temperature or under-temperature automatic power down.
4.2.2.1

Power down SIM900D by the PWRKEY Pin

User can power down SIM900D 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.
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 SIM900D by AT Command

SIM900D 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.
SIM900D_Hardware Design_V2.02
Figure 14: Timing of power down SIM900D by PWRKEY
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Smart Machine Smart Decision
2012-05-07