Smart Machine Smart Decision
SIM800H _Hardware Design_V2.03
24
2016-10-10
save data before completely shut down. Before 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 or VDD_EXT, which is at low level at this time.
4.2.2.2.
Power down SIM800H by AT Command
SIM800H 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 or VDD_EXT, which is at low level at this time.
Note:For detail about AT command “AT+CPOWD”, please refer to document [1].
4.2.2.3.
Over-Voltage or Under-Voltage Power Down
The module software monitors the VBAT voltage constantly.
If the voltage ≤ 3.5V, the following URC will be reported:
UNDER-VOLTAGE WARNNING
If the voltage ≥ 4.3V, the following URC will be reported:
OVER-VOLTAGE WARNNING
If the voltage < 3.4V, the following URC will be reported, and the module will be automatically powered down.
UNDER-VOLTAGE POWER DOWN
If the voltage > 4.4V, the following URC will be reported, and the module will be automatically powered down.
OVER-VOLTAGE 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 or VDD_EXT, which is at low level at this time.
4.2.2.4.
Restart SIM800H by PWRKEY Pin:
When the module works normally, if the customer wants to restart the module, the time after STATUS pin
changed to low should be at least 800ms. The module needs enough time to power down completely.
PWRKEY
T
2
≥
2s
STATUS
T
3
>800ms
1.5s<T
1
<2s
Figure 14:Timing of restart SIM800H
4.2.3.
Reset Function
SIM800H also has a RESET pin (pin 49) used to reset the module. This function is used as an emergency reset
only when AT command “AT+CPOWD=1” and the PWRKEY pin has no effect. Customer can pull the RESET
SIMCOM
CONFIDENTIAL
FILE
