I²C

I²C (Inter-Integrated Circuit), pronounced I-squared-C, is a multi-master, multi-slave, single-ended, serial computer bus invented by Philips Semiconductor (now NXP Semiconductors).

Using a I²C Interface in Driver

Configuring `driver.json`

To use a I²C interface in a driver, you need to have an input with type "i2c" in the driver.json:

{
    "models": [],
    "inputs": {
        "i2c": {
            "type": "i2c",
            "args": {
                "address": -1
            }
        }
    }
}

In the JSON configuration above, the first "i2c" is just the name of the I²C interface (you can change it to something else if you want to),
which will be used as the key to get the interface instance in the driver.
And the "type": "i2c" informs Ruff framework to distribute an I²C interface instead of others.

Arguments

`address`

Required, address of this I²C interface. You can usually find this value from the hardware datasheet.

Writing a Driver

'use strict';

var driver = require('ruff-driver');

module.exports = driver({
    attach: function (inputs) {
        this._i2c = inputs['i2c'];
    },
    exports: {
        getUselessData: function (callback) {
            this._i2c.readByte(0x01, function (error, value) {
                if (error) {
                    callback(error);
                    return;
                }

                callback(undefined, 0xff - value);
            });
        }
    }
});