Interfacing GSM SIM900A With Arduino

interfacing sim900a gsm module

Hello Friends ! 

We are bringing to you the Tutorial for interfacing a SIM900A GSM Module with Arduino. This project uses Arduino Uno & SIM900A module and can be used to send a Text Message from your SIM900A to your Mobile phone.

SIM900A GSM/GPRS Modem is built with Dual-Band GSM/GPRS engine- SIM900A works on frequencies 900/ 1800 MHz. The Modem is coming with RS232 interface, which allows you connect PC as well as a Microcontroller with RS232 Chip(MAX232).

The baud rate is configurable from 9600-115200 through AT command. The SIM900A GSM Modem is having internal TCP/IP stack to enable you to connect with internet via GPRS. It is suitable for SMS, Voice as well as DATA transfer application in M2M interface. Interfacing a SIM900A GSM module is quite straightforward and should not be an issue if everything is done as told.

Step 1: What We Need 

1) 1 x GSM SIM900A  (Buy here)
2) 1 x Arduino Uno (Buy here)
3) 1 x SIM Card 
2) 1 x Jumper Wires (Buy here)
3) 1 x Power adapter 12V (Buy here)

Step 2: Booting Up SIM900A

1. Insert your SIM card to GSM module and lock it.

2. Power up your GSM Modem by connecting the 12V Adapter. Note you need a strong power source and minimum 1A current. Small 9V battery won’t work here.

3. Now wait for some time and see the blinking rate of  ‘Network LED’. GSM module will take some time to establish connection with mobile network.

4. Once the connection is established successfully, the status/network LED will blink continuously every 3 seconds. You may try making a call to the mobile number of the SIM card inside GSM module. If you hear a ring back, the gsm module has successfully established network connection.

Step 3: Pin Connection

Arduino         =>        SIM900A

D9                   =>         Tx

D10                 =>         Rx

Gnd                =>         Gnd

Step 4: Upload the code

Code and connection diagram can be downloaded here.  

Step 5: Output after uploading the code

Once the code is successfully uploaded, you should receive a test SMS as shown in the video above. 

Learn more here : 
1) SIM900A AT Commands 
2) Codes & Schematics

In case of any questions or queries, feel free to post below.

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