OLED JS Pi

What is this?

A NodeJS driver for I2C/SPI compatible monochrome OLED screens. Only I2C is supported at this time. Compatible with Raspberry Pi, Works with 128 x 32, 128 x 64, 96 x 16 and 64x48 sized screens, of the SSD1306 OLED/PLED Controller (read the datasheet here).

This based on the Blog Post and code by Suz Hinton - Read her blog post about how OLED screens work!

OLED screens are really cool - now you can control them with JavaScript!

Install

If you haven't already, install NodeJS.

npm install oled-ssd1306-i2c

I2C screens

Hook up I2C compatible oled to the Raspberry Pi. Pins: SDL and SCL.

I2C example

var oled = require('oled-ssd1306-i2c');

var opts = {
  width: 128,
  height: 64,
};

var oled = new oled(opts);

// do cool oled things here

The above code uses the default I2C address of 0x3C and the I2C device /dev/i2c-1 (default on newer Raspberry Pi boards).

Additional options that can be passed, with default values shown:

var opts = {
  width: 128, // screen width
  height; 32, // screen height
  address: 0x3C, // Pass I2C address of screen if it is not the default of 0x3C
  device: '/dev/i2c-1', // Pass your i2c device here if it is not /dev/i2c-1
  microview: true, // set to true if you have a microview display
};

Allowable combinations for screen width and height are: 128x32, 128x64, 96x16 and 64x48.

Wait, how do I find out the I2C address of my OLED screen?

You can use the i2c npm library for this. Make sure the display is connected to the I2C bus with pull-ups and run the following:

npm install i2c

Then run the following script:

var i2c = require('i2c');
var address = 0x3C;
var wire = new i2c(address, {device: '/dev/i2c-1'}); 
 
wire.scan(function(err, data) {
  // result contains an array of addresses 
});

This will return the I2C addresses of any I2C devices connected to the bus at /dev/i2c-1. If you have other devices than the screen attached, you will need to manually filter those out.

Available methods

clearDisplay

Fills the buffer with 'off' pixels (0x00). Optional bool argument specifies whether screen updates immediately with result. Default is true.

Usage:

oled.clearDisplay();

dimDisplay

Lowers the contrast on the display. This method takes one argument, a boolean. True for dimming, false to restore normal contrast.

Usage:

oled.dimDisplay(true|false);

invertDisplay

Inverts the pixels on the display. Black becomes white, white becomes black. This method takes one argument, a boolean. True for inverted state, false to restore normal pixel colors.

Usage:

oled.invertDisplay(true|false);

turnOffDisplay

Turns the display off.

Usage:

oled.turnOffDisplay();

turnOnDisplay

Turns the display on.

Usage:

oled.turnOnDisplay();

drawPixel

Draws a pixel at a specified position on the display. This method takes one argument: a multi-dimensional array containing either one or more sets of pixels.

Each pixel needs an x position, a y position, and a color. Colors can be specified as either 0 for 'off' or black, and 1 or 255 for 'on' or white.

Optional bool as last argument specifies whether screen updates immediately with result. Default is true.

Usage:

// draws 4 white pixels total
// format: [x, y, color]
oled.drawPixel([
	[128, 1, 1],
	[128, 32, 1],
	[128, 16, 1],
	[64, 16, 1]
]);

drawLine

Draws a one pixel wide line.

Arguments:

• int x0, y0 - start location of line
• int x1, y1 - end location of line
• int color - can be specified as either 0 for 'off' or black, and 1 or 255 for 'on' or white.

Optional bool as last argument specifies whether screen updates immediately with result. Default is true.

Usage:

// args: (x0, y0, x1, y1, color)
oled.drawLine(1, 1, 128, 32, 1);

fillRect

Draws a filled rectangle.

Arguments:

• int x0, y0 - top left corner of rectangle
• int x1, y1 - bottom right corner of rectangle
• int color - can be specified as either 0 for 'off' or black, and 1 or 255 for 'on' or white.

Optional bool as last argument specifies whether screen updates immediately with result. Default is true.

Usage:

// args: (x0, y0, x1, y1, color)
oled.fillRect(1, 1, 10, 20, 1);

drawRect

Draws an empty rectangle.

Arguments:

• int x0, y0 - top left corner of rectangle
• int x1, y1 - bottom right corner of rectangle
• int color - can be specified as either 0 for 'off' or black, and 1 or 255 for 'on' or white.

Optional bool as last argument specifies whether screen updates immediately with result. Default is true.

Usage:

// args: (x0, y0, x1, y1, color)
oled.drawRect(1, 1, 10, 20, 1);

drawCircle

Draws an empty circle.

Arguments:

• int x - x of circle's center
• int y - y of circle's center
• int r - radius of circle
• int color - can be specified as either 0 for 'off' or black, and 1 or 255 for 'on' or white.

Optional bool as last argument specifies whether screen updates immediately with result. Default is true.

Usage:

// args: (x, y, r, color)
oled.drawCircle(30, 10, 5, 1);

drawBitmap

Draws a bitmap using raw pixel data returned from an image parser. The image sourced must be monochrome, and indexed to only 2 colors. Resize the bitmap to your screen dimensions first. Using an image editor or ImageMagick might be required.

Optional bool as last argument specifies whether screen updates immediately with result. Default is true.

Tip: use a NodeJS image parser to get the pixel data, such as pngparse. A demonstration of using this is below.

Example usage:

npm install pngparse

var pngparse = require('pngparse');

pngparse.parseFile('indexed_file.png', function(err, image) {
	oled.drawBitmap(image.data);
});

This method is provided as a primitive convenience. A better way to display images is to use NodeJS package png-to-lcd instead. It's just as easy to use as drawBitmap, but is compatible with all image depths (lazy is good!). It will also auto-dither if you choose. You should still resize your image to your screen dimensions. This alternative method is covered below:

npm install png-to-lcd

var pngtolcd = require('png-to-lcd');

pngtolcd('nyan-cat.png', true, function(err, bitmap) {
  oled.buffer = bitmap;
  oled.update();
});

startScroll

Scrolls the current display either left or right. Arguments:

• string direction - direction of scrolling. 'left' or 'right'
• int start - starting row of scrolling area
• int stop - end row of scrolling area

Usage:

// args: (direction, start, stop)
oled.startscroll('left', 0, 15); // this will scroll an entire 128 x 32 screen

stopScroll

Stops all current scrolling behaviour.

Usage:

oled.stopscroll();

setCursor

Sets the x and y position of 'cursor', when about to write text. This effectively helps tell the display where to start typing when writeString() method is called.

Call setCursor just before writeString().

Usage:

// sets cursor to x = 1, y = 1
oled.setCursor(1, 1);

writeString

Writes a string of text to the display.
Call setCursor() just before, if you need to set starting text position.

Arguments:

• obj font - font object in JSON format (see note below on sourcing a font)
• int size - font size, as multiplier. Eg. 2 would double size, 3 would triple etc.
• string text - the actual text you want to show on the display.
• int color - color of text. Can be specified as either 0 for 'off' or black, and 1 or 255 for 'on' or white.
• bool wrapping - true applies word wrapping at the screen limit, false for no wrapping. If a long string without spaces is supplied as the text, just letter wrapping will apply instead.
• int linespacing - amount of spacing between lines of text on the screen. Negative numbers are also ok.

Optional bool as last argument specifies whether screen updates immediately with result. Default is true.

Before all of this text can happen, you need to load a font buffer for use. A good font to start with is NodeJS package oled-font-5x7.

Usage:

npm install oled-font-5x7

var font = require('oled-font-5x7');

// sets cursor to x = 1, y = 1
oled.setCursor(1, 1);
oled.writeString(font, 1, 'Cats and dogs are really cool animals, you know.', 1, true);

update

Sends the entire buffer in its current state to the oled display, effectively syncing the two. This method generally does not need to be called, unless you're messing around with the framebuffer manually before you're ready to sync with the display. It's also needed if you're choosing not to draw on the screen immediately with the built in methods.

Usage:

oled.update();

Forked from https://github.com/kd7yva/oled-js-pi