SIM900 Hardware Design
When power on procedure completes, the SIM900A will send out following result code to indicate the module is
ready to operate when set as fixed baud rate.
RDY
This result code does not appear when autobauding is active.
3.4.1.2 Turn on SIM900A Using the PWRKEY Pin and PWRKEY_OUT Pin (Power on)
User can turn on SIM900A by connecting PWRKEY Pin and PWRKEY_OUT Pin for a short time and then
release. The simple circuit illustrates as the following figures.
Turn On/Off Impulse
100K
PWRKEY_OUT
MODULE
SIM900
PWRKEY
Figure 9: Turn on SIM900A using driving circuit
PWRKEY_OUT
MODULE
SIM900
PWRKEY
Figure 10: Turn on SIM900A using button
The power on scenarios illustrates as following figure.
SIM900_HD_V1.01
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26.12.2009