AT+GMI - AT Command to Display Manufacturer Identification of GSM Modem

          While using SIM900-TTL GSM/GPRS modem, we will need the manufacturer identification for some purposes. SIM900 provides an AT command to display the manufacturer identification. Different methods are there to input AT commands to SIM900-TTL GSM/GPRS modem. Here we will use an Arduino mega to input the AT commands. I used SIM900-TTL GSM/GPRS modem from Rhydolabz.

Important : SIM card should be inserted to the slot provided on top of modem. Antenna should be fitted to modem.

          Circuit is done as shown in the diagram. Modem requires two voltage sources. One is Vinterface and other is Vin. Vin is given from a DC power supply which is capable of handling an output current of 1A. Vinterface is given from 5V pin of arduino. RX pin of modem is connected to the TX pin of Arduino and TX pin of modem is connected to the RX pin of arduino.

Test command : "AT+GMI=?". Response will be OK.
Execution command : "AT+GMI". Response will be the name of manufacturer.

          Now upload the following program to your arduino board. Before pressing the upload button, either turn off the GSM modem or disconnect the modem pins connected to the RX and TX pins of arduino. Otherwise, uploading will fail.

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void setup()
{

  Serial.begin(2400);
  Serial.write("AT+CMGF=1\r");           //set GSM to text mode
  delay(1500);
 
  Serial.write("AT+GMI\r");                   //Request manufacturer identification
  while(1)
  {
    if(Serial.available())
    {
      Serial.write(Serial.read());
    }
  }
}

void loop()
{

}

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          If the uploading is successfull, open your serial monitor. Serial monitor will display the manufacturer identification. Don't forget to change the baud rate to 2400. Otherwise serial monitor will display an unexpected result.