I am designing a circuit for
SIM900 with a
MCU. I have never designed the circuit for
SIM900 so thought of posting question so that someone can review it.
As per the datasheet,
SIM900 works on power between
3.2v-4.8v. For this I have used
150 & 370 resistors. So it will give output voltage of
4.33v. Below is the schematic for it:
VBAT is the output voltage of 4.33v.
Now in SIM900 I have connected
TX RX pin to the MCU and have made connection for
status and netlight,
SIM Card connector. I have connected
GND. But I am confused with
PWRKEY connections. Below is the schematic :
I don't have an idea about
PWRKEY. I have a
GSM Module and they are using a switch button for it which when pressed connect it to ground. But I do not want this. Is there any alternative for this. Also please review my circuit. Thanks.!