[I2C] Adding the doc file

docs/i2c.md

@@ -0,0 +1,61 @@
+Zephyr.js API for I2C
+========================
+
+* [Introduction](#introduction)
+* [Web IDL](#web-idl)
+* [API Documentation](#api-documentation)
+* [Sample Apps](#sample-apps)
+
+Introduction
+------------
+The I2C API supports the I2C protocol, which allows multiple slave chips to
+communicate with one or more master chips.  Each I2C bus has two signals - SDA
+and SCL. SDA is the data signal and SCL is the clock signal.
+
+Web IDL
+-------
+This IDL provides an overview of the interface; see below for documentation of
+specific API functions.
+
+```javascript
+// require returns a I2C object
+// var i2c = require('i2c');
+
+[NoInterfaceObject]
+interface I2C {
+    I2CBus open(I2CInit init);
+};
+
+dictionary I2CInit {
+    octet bus;
+    I2CBusSpeed speed;
+};
+
+[NoInterfaceObject]
+interface I2CBus {
+    // has all the properties of I2CInit as read-only attributes
+    write(octet device, Buffer data);
+};
+```
+
+API Documentation
+-----------------
+### I2C.open
+
+`I2CBus open(I2CInit init);`
+
+The `init` object lets you set the I2C bus you wish to use and the speed you
+want to operate at.  Speed options are 10, 100, 400, 1000, and 34000. Speed is
+measured in kbs.
+
+### I2CBus.write
+
+`void write(octet device, Buffer data);`
+
+Writes the data to the given device address. The first byte of data typically
+contains the register you want to write the data to.  This will vary from device
+to device.
+
+Sample Apps
+-----------
+* [I2C sample](../samples/I2C.js)