scroll-phat-node

Work-in-progress node.js library for Pimorani's scrollPhat. Partial re-write in Node with some re-use of Python library.

Features:

[x] Set brightness
[x] Set mode 5x11
[x] Set pixels on/off
[x] Load font into bitmaps
[x] Print single character onto screen
[x] Print multiple characters onto screen

Todo:

These remaining items will probably not be finished since animations and timing in asynchronous JavaScript are necessarily hard and complex.

[ ] Scroll text across screen
[ ] Flip output of screen i.e. upside down.
[ ] Scroll-phat HD support

Installation:

Required:

• Node.js v4.2.3
• Raspberry PI or device with I2c support
• I2c correctly set up and functioning

Install node.js via binary distribution, apt-get/pacman or nvm etc. This has been developed/tested on Arch Linux but will also work on other distributions. The i2c-bus library will also require a full make/gcc tool-chain to be installed.

Use Node's npm package manager to install dependencies:

npm install

Demos

• node scroll_test.js
• node app.js

Use in your code

The library aims to be largely compatible with the original Python version, but Node.js is an asynchronous environment, meaning you can quickly get into a deep callback chain. I would suggest looking into the async library control-flow or a Promise library.

var scrollPhat = require('scroll-phat-node');

var scroller = new scroll();
scroller.initialize(function(openErr) {
	if(openErr) {
		return console.error("Can't open i2c.");
	}

	var brightness = 3;
	scroller.setBrightness(brightness, function () {
		scroller.clearPixels();
		scroller.setPixel(1, 1, true);
		scroller.setPixel(1, 2, true);
		scroller.setPixel(1, 3, true);
		scroller.setPixel(1, 4, true);
		scroller.setPixel(1, 5, true);

		scroller.refresh(function () {
			setTimeout(function() {
				scroller.clearPixels();
				scroller.refresh(function () {
					scroller.close();
				});
			}, 1000);
		});
	});
});

Details

Each of the 11 columns can be written to with binary value between 0 and 31, where 0 is off and 31 is fully on. If you need several pixels to be on at once then you need to work out what this would look like in binary. I.e. top and bottom = 10001 = 17