Smart Machine Smart Decision
Figure 10: Powered on/down module using button
The power on scenarios is illustrated as following figure.
Figure 11: Timing of power on module
When power on procedure is completed, SIM900-DS 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
SIM900-DS is powered on. For details, please refer to the chapter “AT+IPR” in document [1].
4.2.2
Power down SIM900-DS
SIM900-DS will be powered down in the following situations
：
z
Normal power down procedure: power down SIM900-DS by the PWRKEY pin.
z
Normal power down procedure: power down SIM900-DS by AT command “AT+CPOWD=1”.
z
Abnormal power down: over-voltage or under-voltage automatic power down.
z
Abnormal power down: over-temperature or under-temperature automatic power down.
4.2.2.1
Power down SIM900-DS by the PWRKEY Pin
User can power down SIM900-DS by pulling down the PWRKEY pin for at least 1 second and release. Please
refer to the power on circuit. The power down scenario is illustrated in following figure.
SIM900-DS_Hardware Design_V1.00
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Содержание SIMCom SIM900-DS
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