Update README

README.md

@@ -4,43 +4,58 @@ Drive WS2812B "NeoPixel" RGB LED strips from a Raspberry Pi using Elixir!
 
 ![NeoPixel strip driven by a Raspberry Pi](nerves_neopixel_rgb.jpg)
 
-This project was designed to make it easy to drive a string of AdaFruit NeoPixels from a Raspberry Pi using [Nerves](http://nerves-project.org).
-The code would probably also work outside of Nerves with minor modifications to the Makefile, if you so desire.
+This project was designed to make it easy to drive a string of AdaFruit
+NeoPixels from a Raspberry Pi using [Nerves](http://nerves-project.org). The
+code would probably also work outside of Nerves with minor modifications to the
+Makefile, if you so desire.
 
-Unfortunately, since the Raspberry Pi has 3.3V I/O outputs and the NeoPixels require 5V I/O input, a little piece of hardware is required.
-You can read more about this in [my blog post about the project](http://www.gregmefford.com/blog/2016/01/22/driving-neopixels-with-elixir-and-nerves).
+Unfortunately, since the Raspberry Pi has 3.3V I/O outputs and the NeoPixels
+require 5V I/O input, a little piece of hardware is required. You can read more
+about this in [my blog post about the
+project](http://www.gregmefford.com/blog/2016/01/22/driving-neopixels-with-elixir-and-nerves).
 
 ## Installation
 
-  1. Add it to your list of dependencies in `mix.exs`:
+1.  Add it to your list of dependencies in `mix.exs`:
 
-        def deps do
-          [{:nerves_neopixel, "~> 0.1.0"}]
-        end
+    ```elixir
+    def deps do
+      [{:nerves_neopixel, "~> 0.3.1"}]
+    end
+    ```
 
-  2. Ensure it is started before your application:
+2. Ensure it is started before your application:
 
-        def application do
-          [applications: [:nerves_neopixel]]
-        end
+    ```elixir
+    def application do
+      [applications: [:nerves_neopixel]]
+    end
+    ```
 
 ## Usage
 
-Supervision trees and an Elixir `Port` are used to maintain fault-tolerance when interfacing with the low-level driver, which is written in C.
-To drive an NeoPixel strip, you just have to configure which GPIO pin to use and how many NeoPixels are in the strip using the `Nerves.NeoPixel.setup` function.
-Once you had a `pid` from the `setup` function, you can call the `Nerves.Neopixel.render` function with the pid and a binary structure representing the pixel data.
+Supervision trees and an Elixir `Port` are used to maintain fault-tolerance when
+interfacing with the low-level driver, which is written in C. To drive an
+NeoPixel strip, you just have to configure which GPIO pin to use and how many
+NeoPixels are in the strip by passing the configuration settings to
+`Nerves.NeoPixel.start_link`.
 
-Here's a simple example:
+Once the process is started, you can call the `Nerves.Neopixel.render` function
+with a list of tuples representing the pixel data, along with the overall
+intensity, as follows:
 
-``` elixir
+```elixir
 alias Nerves.Neopixel
-{:ok, pid} = Neopixel.setup pin: 18, count: 3
-Neopixel.render(
-  pid,
-  <<
-    255, 0, 0, # LED 1: red
-    0, 255, 0, # LED 2: green
-    0, 0, 255  # LED 3: blue
-  >>
-)
+ch0_config = [pin: 18, count: 3]
+ch1_config = [pin: 19, count: 3]
+{:ok, pid} = Neopixel.start_link(ch0_config, ch1_config)
+
+channel = 0
+intensity = 127
+data = [
+  {255, 0, 0},
+  {0, 255, 0},
+  {0, 0, 255},
+]
+Neopixel.render(channel, {intensity, data})
 ```