User's Manual

Smart Machine Smart Decision
SIM868_Hardware_Design_V1.00 23 2016-06-20
When power on procedure is completed, SIM868 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 SIM868 is powered on. For details, please refer to the chapter
“AT+IPR” in document [1].
4.2.2. Power off SIM868
SIM868 will be powered off in the following situations：
 Normal power off procedure: power off SIM868 by the PWRKEY pin.
 Normal power off procedure: power off SIM868 by AT command “AT+CPOWD=1”.
 Abnormal power off: over-voltage or under-voltage automatic power off.
 Abnormal power off: over-temperature or under-temperature automatic power off.
4.2.2.1. Power off SIM868 by the PWRKEY Pin
Customer can power off SIM868 by pulling down the PWRKEY pin for at least 1 second and release. Please refer
to the power on circuit. The power off timing is illustrated in the following figure.
Figure 13: Timing of power off SIM868 by PWRKEY
Note:
1. the module will restart after pull down the pwrkey over 33 seconds.
2. VDD_EXT will power off after STATUS change into low level and the PWRKEY release 55ms..
If 1s<T
1
<2s ， T
2
>2s ；
If 2s≤T
1
<33s ， T
2
>T
1
+55ms
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 off procedure, the module 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.