control ws281x-LEDs with node.js
if you happen to know C++ and node/V8, I would really appreciate any help and feedback on this module. There is certainly lots of room for improvement.
This module provides native bindings to the rpi_ws281x library by Jeremy Garff to provide a very basic set of functions to write data to a strip of ws2811/ws2812 LEDs. will only run on the Raspberry Pi.
setup
this module is available via npm:
npm install rpi-ws281x-native
if you prefer installing from source:
npm install -g node-gyp
git clone --recursive https://github.com/raspberry-node/node-rpi-ws281x-native.git
cd rpi-ws281x-native
node-gyp rebuild
usage
this module exports only three functions to send data to the LED-String.
exports = {
/**
* configures PWM and DMA for sending data to the LEDs
*
* @param numLeds {Number} number of LEDs to be controlled
* @param [options] {Object} (acutally only tested with default-values)
* intialization-options for the library
* (PWM frequency, DMA channel, GPIO, Brightness)
*/
init: function(numLeds, options) {},
/**
* send data to the LED-strip.
*
* @param data {Uint32Array} the pixel-data, 24bit per pixel in
* RGB-format (0xff0000 is red).
*/
render: function(data) {},
/**
* clears all LEDs, resets the PWM and DMA-parts and deallocates
* all internal structures.
*/
reset: function() {}
};testing basic functionality
connect the WS2812-strip to the raspberry-pi as described here
and run the command node examples/rainbow.js <numLeds>.
You should now see some rainbow-colors animation on the LED-strip.
hardware
There is a guide over at adafruit.com on how to get the hardware up and running. Essentially, you need the Raspberry Pi, a logic-level converter to shift the output-voltage of the GPIO from 3.3V up to 5V (should be fast enough to handle 800kHz, the guide mentions the 74AHCT125, mine is an 74HCT125N) and of course an LED-Strip or other types of WS2812-LEDs.
To connect all that together, I'd recommend buying a small breadboard and some jumper-wires. Also, consider buing a 5V power-supply that can deliver up to 60mA per LED (so you'll need 6A to fully power 100 LEDs). For smaller applications, a decent USB-charger should do.
You can buy everything you need at adafruit or any other electronics reseller (germany: check conrad electronic or watterott – this is where i bought most of my stuff).