Wire

Functions
void	begin (void)
void	end (void)
void	setClock (uint32_t freq)
void	beginTransmission (uint8_t address)
uint32_t	endTransmission (uint8_t sendStop=true)
uint8_t	requestFrom (uint8_t address, uint8_t quantity, uint8_t sendStop)
virtual size_t	write (const uint8_t *data, size_t size)
virtual int	available (void)
virtual int	read (void)

Detailed Description

Function Documentation

begin()

void begin

(

void

)

Description

Initiate the Wire library and join the I2C bus as a master

Syntax

Wire.begin();

Returns

void

Example

void setup() {
  Wire.begin();
}

void loop() {
}

end()

void end

(

void

)

Description

End the I2C bus

Syntax

Wire.end();

Returns

void

Example

void setup() {
  Wire.begin();
}

void loop() {
  Wire.end();
}

setClock()

void setClock

(

uint32_t

freq

)

Description

This function modifies the clock frequency for I2C communication. I2C slave devices have no minimum working clock frequency, however 100KHz is usually the baseline

Syntax

Wire.setClock(freq);

Parameters

freq	the value (in Hertz) of desired communication clock. Accepted values are 100000 (standard mode) and 400000 (fast mode)

Returns

void

Example

  void setup() {
    Wire.begin();
Wire.setClock(400000);
  }

  void loop() {
  }

beginTransmission()

void beginTransmission

(

uint8_t

address

)

Description

Begin a transmission to the I2C slave device with the given address. Subsequently, queue bytes for transmission with the write() function and transmit them by calling endTransmission()

Syntax

Wire.beginTransmission(address);

Parameters

address

the 7-bit address of the device to transmit to

Returns

void

Example

void setup() {
  Wire.begin();
}

void loop() {
  Wire.beginTransmission(0b1110000);
  Wire.write(0x35);
  Wire.endTransmission();
}

endTransmission()

uint32_t endTransmission

(

uint8_t

sendStop = true

)

Description

Ends a transmission to a slave device that was begun by beginTransmission() and transmits the bytes that were queued by write()

Syntax

Wire.endTransmission();
Wire.endTransmission(sendStop);

Parameters

sendStop(optional)

true will send a stop message, releasing the bus after transmission. false will send a restart, keeping the connection active(default = false)

Return values

0	success
1	fail

Example

void setup() {
  Wire.begin();
}

void loop() {
  Wire.beginTransmission(0b1110000);
  Wire.write(0x35);
  Wire.endTransmission();
}

requestFrom()

uint8_t requestFrom	(	uint8_t	address,
		uint8_t	quantity,
		uint8_t	sendStop
	)

Description

Used by the master to request bytes from a slave device. The bytes may then be retrieved with the available() and read() functions

Syntax

Wire.requestFrom(address, quantity);
Wire.requestFrom(address, quantity, sensStop);

Parameters

address	the 7-bit address of the device to request bytes from
quantity	the number of bytes to request
sendStop	true will send a stop message after the request, releasing the bus. false will continually send a restart after the request, keeping the connection active(default = false)

Returns

the number of bytes returned from the slave device(Type: byte)

Example

void setup() {
  Wire.begin();
}

void loop() {
  Wire.beginTransmission(0b1110000);
  Wire.write(0x35);
  Wire.endTransmission();

  Wire.requestFrom(0b1110000, 6);

  while(Wire.available()) {
    char c = Wire.read();
    Serial.print(c);
  }
  delay(5000);

}

write()

virtual size_t write ( const uint8_t *  data, size_t  size  )

virtual

Description

Writes data to a slave device

Note

in-between calls to beginTransmission() and endTransmission()

Syntax

Wire.write(value);
Wire.write(data, size);

Parameters

value	a value to send as a single byte
data	an array of data to send as bytes
size	the number of bytes to transmit

Returns

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

Example

  void setup() {
    Wire.begin();
  }

  void loop() {
    Wire.beginTransmission(0b1110000);
    Wire.write(0x35);
    Wire.endTransmission();

    Wire.requestFrom(0b1110000, 6);

    while(Wire.available()) {
      char c = Wire.read();   
      Serial.print(c);
}
    delay(5000);

  }

Reimplemented from Print.

available()

virtual int available ( void  )

virtual

Description

Returns the number of bytes available for retrieval with read()

Syntax

Wire.availavle()

Returns

The number of bytes available for reading

Example

void setup() {
  Wire.begin();
}

void loop() {
  Wire.beginTransmission(0b1110000);
  Wire.write(0x35);
  Wire.endTransmission();

  Wire.requestFrom(0b1110000, 6);

  while(Wire.available()) {
    char c = Wire.read();
    Serial.print(c);
  }
  delay(5000);

}

Implements Stream.

read()

virtual int read ( void  )

virtual

Description

Reads a byte that was transmitted from a slave device to a master

Syntax

Wire.read()

Note

read() inherits from the Stream utility class

Returns

The next byte received

Example

void setup() {
  Wire.begin();
}

void loop() {
  Wire.beginTransmission(0b1110000);
  Wire.write(0x35);
  Wire.endTransmission();

  Wire.requestFrom(0b1110000, 6);

  while(Wire.available()) {
    char c = Wire.read();
    Serial.print(c);
  }
  delay(5000);

}

Implements Stream.