SIM900A GSM Module: How to use SIM900A?

The SIM900A is a common GSM/GPRS module found in various cell phones and PDAs. The module can also be used to create Internet of Things (IoT) and Embedded Apps. The SIM900A is a dual-band GSM/GPRS engine that operates on the EGSM 900MHz and DCS 1800MHz frequencies. SIM900A supports the GPRS coding schemes CS-1, CS-2, CS-3, and CS-4 and has GPRS multi-slot class 10/class 8 (optional).

• Single supply voltage: 3.4V – 4.5V

• Power saving mode: Typical power consumption in SLEEP mode is 1.5mA

• Frequency bands: SIM900A Dual-band: EGSM900, DCS1800. The SIM900A can search the two frequency bands automatically. The frequency bands also can be set by AT command.

• GSM class: Small MS

• GPRS connectivity:GPRS multi-slot class 10 (default) , GPRS multi-slot class 8 (option)

• Transmitting power: Class 4 (2W) at EGSM 900, Class 1 (1W) at DCS 1800

• Operating Temperature: -30ºC to +80ºC

• Storage Temperature: -5ºC to +90ºC

• DATA GPRS: download transfer max is 85.6KBps, Upload transfer max 42.8KBps

• Supports CSD, USSD, SMS, FAX

• Supports MIC and Audio Input

• Speaker Input

• Features keypad interface

• Features display interface

• Features Real-Time Clock

• Supports UART interface

• Supports single SIM card          

• Firmware upgrade by debug port

• Communication by using AT commands

SIM900A Pinout

SIM900A 2D Dimension

• Cellular Communication

• Robotics

• Mobile Phone Accessories

• Servers

• Computer Peripherals

• Automobile

• USB Dongles

• SIM800L

• QUECTEL M95

Communication with this module is done via UART or RS232 interface, as seen above. Through the UART interface, data is delivered to or received from the module.

The module is usually powered by a conventional +4.0V power source. It requires +4.5V regulated electricity to operate, and any greater voltage may cause harm to the module. Furthermore, the power source must be capable of delivering a peak current of 2A. The UART interface is set up as shown in the diagram. Simply connect the RXD of the module to the TXD of the Arduino, and the TXD to the RXD of the ARDUINO. For voltage reference, the controller and module's ground must be linked. The MIC is connected to AUDIO IN, while the speaker or headset is connected to AUDIO OUT. Finally, we must attach a functional GSM SIM card to the module. On powering the module, the NET LIGHT LED will blink periodically to state a successful connection.

Following the completion of all connections, we must build a program for the microcontroller to exchange data with the module. Because the data exchange sequence between the controller and the module is so complicated, we'll use libraries that have already been created for the module. You can get controller and module libraries from their websites. Communication is simplified when these libraries are used. All you have to do is download and use these libraries in your projects. After you've included the header file, you may tell the controller to send or receive data using simple commands in the program. Based on the protocol set up in libraries, the controller delivers data to the module through UART Interface. The module uses the cellular network to relay this information to another GSM user. If the module receives any data from the cellular network (or another GSM user) it will transmit it to the controller through UART serial communication.

• SIM900A Datasheet

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