Smart Machine Smart Decision
SIM800H _Hardware Design_V2.03
23
2016-10-10
Underfined
Active
1.2s
VBAT
PWRKEY
(INPUT)
t>3s
VDD_EXT
STATUS
t>1s
Serial port
T>1.5s
V
IL
<0.7V
Figure 12: Timing of power on module
When power on procedure is completed, SIM800H will send following URC to indicate that the module is ready
to operate at fixed baud rate.
RDY
This URC does not appear when autobauding function is active.
Note: Customer can use AT command “AT+IPR=x” to set a fixed baud rate and save the configuration to non-volatile flash
memory. After the configuration is saved as fixed baud rate, the Code “RDY” should be received from the serial port every time
when SIM800H is powered on. For details, please refer to the chapter “AT+IPR” in document [1].
4.2.2.
Power down SIM800H
SIM800H will be powered down in the following situations
：
Normal power down procedure: power down SIM800H by the PWRKEY pin.
Normal power down procedure: power down SIM800H by AT command “AT+CPOWD=1”.
Abnormal power down: over-voltage or under-voltage automatic power down.
4.2.2.1.
Power down SIM800H by the PWRKEY Pin
Customer can power down SIM800H by pulling down the PWRKEY pin for at least 1.5 second and release.
Please refer to the power on circuit. The power down timing is illustrated in the following figure.
PWRKEY
t>1.6s
VDD_EXT
STATUS
1.5s<t<33s
Serial
Active
Undefined
(INPUT)
V
IL
<0.7V
Figure 13: Timing of power down SIM800H by PWRKEY
This procedure makes the module log off from the network and allows the software to enter into a secure state to
SIMCOM
CONFIDENTIAL
FILE
