Update README

README.md

@@ -1 +1,87 @@
 # usb-i2c-android
+
+This is a library for communication with [I²C](https://en.wikipedia.org/wiki/I%C2%B2C) devices on Android using USB I²C adapters connected to the
+[Android USB Host (OTG)](http://developer.android.com/guide/topics/connectivity/usb/host.html). 
+No root access or special kernel drivers are required.
+
+## Supported adapters
+
+* [I2C-Tiny-USB](https://github.com/harbaum/I2C-Tiny-USB)
+* [Silicon Labs CP2112](http://www.silabs.com/Support%20Documents/TechnicalDocs/CP2112.pdf)
+
+## Usage
+
+Add jitpack.io repository to your root build.gradle:
+```gradle
+allprojects {
+    repositories {
+        ...
+        maven { url 'https://jitpack.io' }
+    }
+}
+```
+Add library to dependencies:
+```gradle
+dependencies {
+    implementation 'com.github.3cky:usb-i2c-android:1.0'
+}
+```
+
+Add USB host feature usage to your app manifest:
+
+```xml
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="...">
+    <uses-feature android:name="android.hardware.usb.host" />
+    ...
+</manifest>
+```
+
+Example code:
+
+```java
+import com.github.ykc3.android.usbi2c.UsbI2cAdapter;
+import com.github.ykc3.android.usbi2c.UsbI2cDevice;
+import com.github.ykc3.android.usbi2c.UsbI2cManager;
+...
+
+// Get Android UsbManager
+UsbManager usbManager = (UsbManager) getSystemService(Context.USB_SERVICE);
+
+// Find all connected I²C adapters
+UsbI2cManager usbI2cManager = UsbI2cManager.create(usbManager).build();
+List<UsbI2cAdapter> i2cAdapters = usbI2cManager.getAdapters();
+if (i2cAdapters.isEmpty()) {
+    return;
+}
+
+// Get first adapter
+UsbI2cAdapter i2cAdapter = i2cAdapters.get(0);
+
+// Request USB access permission
+usbManager.requestPermission(i2cAdapter.getUsbDevice(), usbPermissionIntent);
+...
+// USB permission intent handler called with success result
+
+// Open adapter
+i2cAdapter.open();
+
+// Get device with I²C address 0x42
+UsbI2cDevice i2cDevice = i2cAdapter.getDevice(0x42);
+
+// Read device register 0x01.
+// Throws java.lang.IOException if device is not connected or I/O error caused 
+byte value = i2cDevice.readRegByte(0x01);
+
+// Close adapter
+i2cAdapter.close();
+```
+
+## Sample app
+
+For simple I²C device scanner sample app, check an `app` module. 
+
+## License
+
+This library is licensed under *LGPL Version 2.1*.  Please see LICENSE.txt for the
+complete license.