Wire (I2C)

write()

Queues bytes for transmission from a master to slave device (in-between calls to beginTransmission() and endTransmission()), or writes data from a slave device in response to a request from a master.

The default buffer size is 32 bytes; writing bytes beyond 32 before calling endTransmission() will be ignored. The buffer size can be increased by using acquireWireBuffer().

// SYNTAX
Wire.write(value);
Wire.write(string);
Wire.write(data, length);

Parameters:

• value: a value to send as a single byte
• string: a string to send as a series of bytes
• data: an array of data to send as bytes
• length: the number of bytes to transmit (Max. 32)

Returns: byte

write() will return the number of bytes written, though reading that number is optional.

// EXAMPLE USAGE

// Master Writer running on Device No.1 (Use with corresponding Slave Reader running on Device No.2)

void setup() {
  Wire.begin();              // join i2c bus as master
}

byte x = 0;

void loop() {
  Wire.beginTransmission(4); // transmit to slave device #4
  Wire.write("x is ");       // sends five bytes
  Wire.write(x);             // sends one byte
  Wire.endTransmission();    // stop transmitting

  x++;
  delay(500);
}