SimCom SIM800C, Проектирование аппаратного обеспечения

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SIM800C_Hardware_Design_V1.02
20
2015-4-27
When power on procedure is completed, SIM800C 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 SIM800C is powered on. For details, please refer to the chapter
“AT+IPR” in document [1].
4.2.2. Power off SIM800C
SIM800C will be powered off in the following situations
：
 Normal power off procedure: power off SIM800C by the PWRKEY pin.
 Normal power off procedure: power off SIM800C 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 SIM800C by the PWRKEY Pin
Customer can power off SIM800C 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.
P W R K E Y
V D D _E X T
S T A T U S
V
IL
<0.7V
S erial port
U ndifined A ctive
(input)
T
3
=2s
1s<T
1
<33s
T
2
≥2s
Figure 13: Timing of power off SIM800C 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 not be executed any more. Power off mode can also be indicated by STATUS
pin, which is at low level at this time.
4.2.2.2. Power off SIM800C by AT Command