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Libraries \ Wire

Reference for Wiring version 1.0 Build 0100+ If you have a previous version, use the reference included with your software. If see any errors or have any comments, let us know.

Class | Wire
Name |

### begin()

Examples |
    #include "Wire.h"

    void setup()
    {
      // join i2c bus (address optional for master)
      Wire.begin();
      // start serial for output
      Serial.begin(9600);
    }

    void loop()
    {
      // request 6 bytes from slave device #2
      Wire.requestFrom(2, 6);

      // slave may send less than requested
      while(Wire.available())
      {
        // receive a byte as character
        char c = Wire.read();
        Serial.print(c);  // print the character
      }

      delay(500);
    }

    #include "Wire.h"

    void setup()
    {
      // join i2c bus with address #4
      Wire.begin(4);
      // register event
      Wire.onReceive(receiveEvent);
      // start serial for output
      Serial.begin(9600);
    }

    void loop()
    {
      delay(100);
    }

    // function that executes whenever data is received from master
    // this function is registered as an event, see setup()
    void receiveEvent(int howMany)
    {
      // loop through all but the last
      while(1 < Wire.available())
      {
        // read byte as a character
        char c = Wire.read();
        Serial.print(c);  // print the character
      }
      // read byte as an integer
      int x = Wire.read();
      Serial.println(x);  // print the integer
    }

Description | The Wiring TwoWire library allows for easily reading and writing data to external devices using the Two Wire Interface (TWI or I2C) protocol. The TWI protocol and interface were developed by Phillips. On Wiring v1 boards the SCL and SDA pins are: 0 and 1. On Wiring S board the SCL and SDA pins are: 8 and 9. It is possible to connect multiple TWI devices to the TWI pins creating a network or bus of devices and communicate with them by means of an address. The TWI can be configured to act as a Master or a Slave in a network of devices. The begin() method is used to initiate the TWI as a Master and the begin(address) method is used to join the TWI bus a slave using the address specified. In both cases the begin method must be must be placed in the setup() method.
Syntax |
    Wire.begin()
Parameters |

address | An integer value between 0 and 127 specifying the address to be used when joining the TWI bus.
Wire | The hardware TWI port

Returns | None
Usage | Application

Updated on July 07, 2011 11:12:03pm PDT