Smart Machine Smart Decision
SIM868_Series_Hardware_Design_V1.06
27
2017-07-13
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 SIM868 is powered on. For details, please refer to the chapter
“AT+IPR” in document [1].
5.3.2.
Power off GSM
GSM will be powered off in the following situations
：
Power off GSM by the PWRKEY pin.
Power off GSM by AT command “AT+CPOWD=1”.
5.3.2.1.
Power off GSM by the PWRKEY Pin
Customer can power off GSM by pulling down the PWRKEY pin for at least 1.5 second and release. The power
off timing is illustrated in Figure 16.
PWRKEY
VDD_EXT
STATUS
V
IL
<0.7V
Serial port
Undifined
Active
(input)
T
3
=2s
1.5s<T
1
<33s
T
2
≥
2s
Figure 16: Timing of power off GSM
Note:
1.
The GSM will restart after pulling down the PWRKEY over 33 seconds.
2.
VDD_EXT will power off after STATUS changes into low level and the PWRKEY release 55ms.
If 1.5s<T
1
<2s
，
T
2
>2s
；
If 2s≤T
1
<33s
，
T
2
>T
1
+55ms
This procedure makes the GSM log off from the network and allows the software to enter into a secure state to
save data before completely shut off.
Before the completion of the power off procedure, the GSM will send URC:
NORMAL POWER OFF
At this moment, AT commands can’t be executed any more. Power off mode can also be indicated by STATUS pin,
which is at low level at this time.
5.3.2.2.
Power off GSM by AT Command
GSM can be powered off by AT command “AT+CPOWD=1”. This procedure makes the GSM log off from the
network and allows the software to enter into a secure state to save data before completely shut off.
Before the completion of the power off procedure, the GSM will send URC:
SIMCOM
CONFIDENTIAL
FILE
