Asynchronous OLED JS Pi over i2c-bus

What is this?

This is a fork of the package oled-rpi-i2c-bus, which itself is a fork of oled-js-pi. This version works through the i2c-bus package and does not use the i2c package.

A NodeJS driver for I2C/SPI compatible monochrome OLED screens; to be used on the Raspberry Pi. Works with 128 x 32, 128 x 64, and 96 x 16 sized screens, of the SSD1306/SH1106 OLED/PLED Controller (read the datasheet here).

This version includes two significant updates:

1. Switched to using the asynchronous methods of the i2c-bus package for improved performance and non-blocking operations.
2. Migrated to ES6 modules for modern JavaScript syntax and better module management.

The original code is based on the blog post and code by Suz Hinton.

Install

Raspberry Pi allows for software I2C. To enable software I2C, add dtoverlay=i2c-gpio,bus=3 to /boot.config.txt. The software I2C would be available on bus no 3 where the SDA is on pin GPIO23/BCM 16 and SCK is on pun GPIO24/BCM 18.

If you haven't already, install NodeJS.

npm install oled-rpi-i2c-bus-async

For SH1106, if you get an error:

"Error: , Remote I/O error"

You might have to lower the baudrate by adding the following line to /boot/config.txt and rebooting the Pi

dtparam=i2c_baudrate=10000

This is a known issue with Raspberry Pi as noted in Raspberry Pi I2C hardware bug. Alternatively, use software I2C.

I2C screens

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

I2C example

import i2c from 'i2c-bus';
import Oled from 'oled-rpi-i2c-bus-async';

const opts = {
  width: 128,
  height: 64,
  address: 0x3D,
  bus: 1,
  driver: "SSD1306"
};

const setupOled = async () => {
  try {
    const i2cBus = await i2c.openPromisified(opts.bus);
    const oled = new Oled(i2cBus, opts);

    // do cool oled things here

  } catch (err) {
    console.error('Error:', err);
  }
};

setupOled();

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

Check your screen's documentation...

Available methods

clearDisplay

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

Usage:

await 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:

await oled.dimDisplay(true);

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:

await oled.invertDisplay(true);

turnOffDisplay

Turns the display off.

Usage:

await oled.turnOffDisplay();

turnOnDisplay

Turns the display on.

Usage:

await 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]
await 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)
await oled.drawLine(1, 1, 128, 32, 1);

fillRect

Draws a filled rectangle.

Arguments:

• int x0, y0 - top left corner of rectangle
• int w, h - width and height 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)
await oled.fillRect(1, 1, 10, 20, 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

// Parse the PNG file and draw the bitmap
const image = await new Promise((resolve, reject) => {
  pngparse.parseFile('indexed_file.png', (err, image) => {
    if (err) reject(err);
    else resolve(image);
  });
});

await 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

// Convert PNG to LCD bitmap and update the display
const bitmap = await new Promise((resolve, reject) => {
  pngtolcd('nyan-cat.png', true, (err, bitmap) => {
    if (err) reject(err);
    else resolve(bitmap);
  });
});

oled.buffer = bitmap;
await oled.update();

drawRGBAImage

Draw an RGBA coded image at specific coordinates. This only supports a monochrome OLED so transparent pixels must be 100% transparent, off pixels should have an RGB value of (0, 0, 0), and pixels with any color value will be considered on.

Use a library such as pngjs to read a png file into the required rgba data structure.

Example with PNG Stream

import fs from 'fs';
import { PNG } from 'pngjs';
import i2c from 'i2c-bus';
import Oled from 'oled-i2c-bus';

const setupOled = async () => {
  const i2cBus = await i2c.openPromisified(0);

  const opts = {
    width: 128,
    height: 64,
    address: 0x3C
  };

  const display = new Oled(i2cBus, opts);

  // Clear the display
  await display.clearDisplay();

  // Turn on the display
  await display.turnOnDisplay();

  // Function to draw the image
  const drawImage = async (image) => {
    const x = Math.floor(Math.random() * (display.WIDTH - image.width / 2));
    const y = Math.floor(Math.random() * (display.HEIGHT - image.height / 2));
    await display.drawRGBAImage(image, x, y);
  };

  // Read and draw the PNG image
  fs.createReadStream('./test.png')
    .pipe(new PNG({ filterType: 4 }))
    .on('parsed', async function () {
      setInterval(async () => {
        await drawImage(this);
      }, 1000);
    });
};

setupOled();

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)
await oled.startscroll('left', 0, 15); // this will scroll an entire 128 x 32 screen

stopScroll

Stops all current scrolling behaviour.

Usage:

await 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
await 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.

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

import font from 'oled-font-5x7';

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

Checkout https://www.npmjs.com/package/oled-font-pack for all-in-one font package.

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:

await oled.update();

battery

Draw a battery level in percentage indicator. This method allows for up to 4 different states of the battery:

• 0 bar : battery < 10%
• 1 bar : 10% >= battery < 40%
• 2 bar : 40% >= battery < 70%
• 3 bar : battery >= 70%

Arguments:

• int x - start column
• int y - start row
• int percentage - battery level percentage

usage:

// args: (x,y,percentage)
await oled.battery(1,1,20);

bluetooth

Draw a bluetooth icon

usage:

//args: (x,y)
await oled.bluetooth(1,1);  

wifi

Draw a WiFi signal strength in percentage indicator. This method allows for up to 4 different signal strength of the WiFi signal:

• 0 bar : signal < 10%
• 1 bar : 10% >= signal < 40%
• 2 bar : 40% >= signal < 70%
• 3 bar : signal >= 70%

Arguments:

• int x - start column
• int y - start row
• int percentage - signal strength in percentage

usage:

// args: (x,y,percentage)
await oled.wifi(1,1,20);

image

A wrapper for drawRGBAImage that supports a fix animation. The animation always start from x=1 and y=1.

Arguments:

• int x - start column (ignored on animation = true)
• int y - start row (ignored on animation=true)
• string image - full path to the image or the filename of the image in the resources folder
• object font - font to draw "error" message
• boolean clear - clear the display before the draw
• boolean reset - stop all animations
• boolean animated - enable/disable animation
• boolean wrapping - enable/disable of the error message wrapping

usage:

import font from 'oled-font-5x7';
await oled.image(1,1,'rpi-frambuesa.png',font.oled_5x7,true,false,false,true);