Smart Machine Smart Decision
SIM800_Hardware Design_V1.10
23
2018-08-13
4.7K
47K
Turn on/off
impulse
PWRKEY
Power on/off
logic
100K
VBAT
Module
1K
Figure 10: Power on/off module using transistor
PWRKEY
Power on/off
logic
100K
VBAT
Module
1K
Figure 11: Power on/off module using button
The power on timing is illustrated as following figure.
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].
