Wire.write(data, length) Parameters value: A value to send as a single byte Syntax unsigned char Wire.endTransmission() Parameters None Returns 0 write Description Adds a character string or data to the end of the transmit buffer. Syntax Wire.beginTransmission(unsigned char address) Parameters address: The 7-bit address of the device to which to transmit Returns None endTransmission Description Ends a transmission to a slave device that was begun by beginTransmission() and transmits the bytes that were queued by write(). Subsequently, queue bytes for transmission with the write() function and transmit them by calling endTransmission(). beginTransmission Description Begin a transmission to the I 2C slave device with the given address. Returns Byte: The number of bytes returned from the slave device. False will continually send a restart after the request, keeping the connection active. True will send a stop message after the request, releasing the bus. Quantity: The number of bytes to request. Wire.requestFrom(address, quantity, stop) Parameters address: The 7-bit address of the device from which to request bytes. Syntax Wire.requestFrom(address, quantity) The bytes may then be retrieved with the available() and read() functions. Syntax Wire.begin() Parameters None Returns None requestFrom Description Used by the master to request bytes from a slave device. Wire: 21(SCL), 20(SDA) begin Description Initiates the Wire library. Not supported for operating as a slave device. The available channels and pin numbers are as follows and can also be confirmed on the pin map. The pull-up to communication lines is needed. Code samples in the reference are released into the public domain.This is an I 2C communications library that facilitates two-wire class communications with I 2C/TWI devices (also called 'Wire Library'). The text of the Arduino reference is licensed under aĬreative Commons Attribution-ShareAlike 3.0 License. shift the value one bit to the right), yielding an address between 0 and 127.Ĭorrections, suggestions, and new documentation should be posted to the Forum. If you have a datasheet or sample code that uses 8 bit address, you'll want to drop the low bit (i.e. The Wire library uses 7 bit addresses throughout. 7 bits identify the device, and the eighth bit determines if it's being written to or read from. There are both 7- and 8-bit versions of I2C addresses. Because of this, send() and receive() have been replaced with read() and write().

On the Arduino Mega, SDA is digital pin 20 and SCL is 21.Īs of Arduino 1.0, the library inherits from the Stream functions, making it consistent with other read/write libraries. On most Arduino boards, SDA (data line) is on analog input pin 4, and SCL (clock line) is on analog input pin 5. This library allows you to communicate with I2C / TWI devices. Reference Language | Libraries | Comparison | Changes

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