Interfacing sim800 / sim900A GSM module with arduino
Here tutorial describes interfacing between a SIM 800 GSM / SIM 900A GSM module with an Arduino board via TTL serial communication.
Arduino gsm module pinout
|Arduino pin||GSM modem pin|
For a TTL serial connection, connect the pins from the GSM device to Arduino as, Rx pin to TX pin and TX pin to Rx pin. Or if the software serial is used, connect to the declared Transmitter and Receiver pins. If the Arduino code uses the serial communication as Serial.begin(9600), the TX and RX pins will be default TX and RX pins of the AVR microcontroller which is labelled on the Arduino UNO board. So just plug to TX pin (pin 1) and the RX pin (pin 0).
E.g: – SoftwareSerial mySerial (2, 3); // RX digital pin 2, TX digital pin 3.
GSM modems may also have a female RS232 serial port for direct connection to PC. In order to work directly with hyper terminal or similar serial terminals using AT commands.
GSM modem booting
Insert the SIM card into the SIM socket of the module and lock it.
The GSM module requires a considerable amount of power to establish a network connection, and for operations. So power from the Arduino board will not be enough for it. So an external power is required for most GSM modules.
The GSM module Commonly has a 12V DC input, which can be connected either via DC socket or through connector pins. Plug a 12V adapter into the Socket or power it by connector pins on the board.
On powered up, the power LED gets ON and the Network Status LED starts to blink. The network LED blink every second and after when the Modem registers the network, the LED will blink in every 3 seconds. The GSM module takes some time, around 60 seconds to establish a connection with mobile networks.