I have my new SIM900A module of SIMCom. I was facing problems while interfacing it with Arduino Mega.
Then I tried to interface it with arduino UNO. So in this instructable I am going to show you how I overcame problems and started playing with GSM AT commands.
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Step 1: SIM900A Interfacing With Arduino Uno
Do the connections as follows:
RX of GSM ------------> RX of arduino
TX of GSM--------------> TX of arduino
Gnd of GSM ----------> Gnd of arduino
Connect SIM900A module to 12V power adapter
I have SIM900A module with RS232 port and my module requires voltage of 12 Volt 1-2 Ampere current rating for reliable operation.
It is not possible to give power from arduino UNO by connecting power pins of GSM module with arduino.
Another problem which I faced was connecting GSM with arduino Mega. I found that my SIM900A module was not getting proper ground from mega.
Now my UNO is giving proper ground to module. It may have happened because Mega have more peripherals on it while UNO has only few peripherals on board.
Step 2: Upload Blank Code to SIM900A
Now connect the arduino uno with PC/laptop using USB.
Open the arduino IDE. Simply upload the blank code in arduino UNO
Step 3: Sending AT Commands
Now open the Serial Monitor
Set the baud rate at 4800 and start seding commands as follows.
When you enter this command you should get response as OK
This command gives the manufacturer identification
In my case it gives output SIMCOM_Ltd
3. AT+ CGMM
This command is used to get the supported frequency bands. With multi-band products
the response may be a combination of different bands.
In my case it gives output SIMCOM_SIM900A
For more commands you can refer the attached PDF