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IoT.js-API-I2C.md

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Module: i2c

Platform Support

The following shows i2c module APIs available for each platform.

Linux
(Ubuntu)		 Raspbian
(Raspberry Pi)		 Nuttx
(STM32F4-Discovery)
i2c.scan O O X
i2c.write O O X
i2c.writeByte O O X
i2c.writeBytes O O X
i2c.read O O X
i2c.readByte O O X
i2c.readBytes O O X
i2c.stream O O X

Constructor

new i2c([address[, options]])

  • address: Number (Default value is 0x23)
  • options: Object

options is an object specifying following information:

  • device: String (Default value is /dev/i2c-1)

Create I2C object. Following methods can be called with I2C object.

For example,

var i2c = require('i2c');
var wire = new i2c(0x23, {device: '/dev/i2c-1'});

wire.scan(function(err, data) {
 // Do something.
});

Events

'data'

  • callback: Function(data)

data is an object specifying following information:

  • address: Number
  • data: Array (an array of bytes)
  • cmd: Number
  • length: Number
  • timestamp: Number

Emitted when stream method is called.

For example,

...
wire.on('data', function(data) {
  console.log('data.timestamp: ' + data.timestamp);
  console.log('data.address: ' + data.address);
  console.log('data.cmd: ' + data.cmd);
  console.log('data.length: ' + data.length);
  console.log('data.data: ' + data.data);
});

wire.stream(0x20, 2, 1000);

Methods

i2c.read(length, callback)

  • length: Number
  • callback: Function(err, res)

Read bytes from I2C device. length is the number of bytes. res contains an array of bytes.

i2c.readByte(callback)

  • callback: Function(err, res)

Read one byte from I2C device. res contains result as a number.

i2c.readBytes(command, length, callback)

  • command: Number
  • length: Number
  • callback: Function(err, res)

Read bytes from I2C device with command. length is the number of bytes. res contains an array of bytes.

i2c.scan(callback)

  • callback: Function(err, data)

Scan I2C device. data contains an array of addresses.

i2c.stream(command, length, delay)

  • command: Number
  • length: Number
  • delay: Number

Read bytes from I2C device with command, continuously. It emits data event. length is the number of bytes. It will pause for the amount of time(delay in ms).

i2c.write(bytes, callback)

  • bytes: Array
  • callback: Function(err)

Write bytes to I2C device. bytes is an array of numbers.

i2c.writeByte(byte, callback)

  • byte: Number
  • callback: Function(err)

Write one byte to I2C device.

i2c.writeBytes(command, bytes, callback)

  • command: Number
  • bytes: Array
  • callback: Function(err)

Write bytes to I2C device with command. bytes is an array of numbers.