There are separate RX and TX ports for 5V and 3.3V devices. Use middle RX and TX ports on 6 pin header which are for 5V device. RX from SIM900A goes to TX of USB to TTL adapter and vice versa. After connecting SIM900A Mini according to diagram perform the following steps.
- Open up PuTTY
- Choose Serial
- Choose Serial line e.g. COM1 (Refer Control Panel>All Control Panel Items>System>Device Manager>Ports)
- Speed or Baud Rate should be 9600
- Click open wait few seconds
Now We have connected SIM900A module to our PC. Let’s test of module by using AT commands. Here is list of few commands to testing purpose.
|AT||Check connection between module and serial monitor|
|AT+CPIN?||Check sim card status|
|AT+CSQ||Check signal quality|
|AT+CGMI||Check the module maker|
|AT+CGMM||Check the module model type|
|AT+CGSN||Check the module IMEI|
|AT+CMGR||Read message, for exmple, AT+CMGR=1 to read message at position 1|