Smart Machine Smart Decision
SIM800_Hardware Design_V1.09
23
2016-06-30
V
IL
<0.7V
Undefind
Active
T=100ms
VBAT
PWRKEY
(INPUT)
t>3s
VDD_EXT
STATUS
T>1.2s
Serial Port
T>1.4s
Figure 12: Timing of power on module
When power on procedure is completed, SIM800 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: User 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 SIM800 is powered on. For details, please refer to the chapter
“AT+IPR” in document [1].
4.2.2.
Power off SIM800
SIM800 will be powered off in the following situations:
Normal power off procedure: power off SIM800 by the PWRKEY pin.
Normal power off procedure: power off SIM800 by AT command “AT+CPOWD=1”.
Abnormal power off: over-voltage or under-voltage automatic power off.
4.2.2.1.
Power off SIM800 by the PWRKEY Pin
User can power off SIM800 by pulling down the PWRKEY pin for at least 1.5 second and then release. Please
refer to the power on circuit. The power off sequence is illustrated in following figure.
