rpi-oled

A collection of NodeJS command line tools and libraries for I2C based SSD1306 compatible monochrome OLED screens. The main difference of this library compared to other forks is the added command line tools. Additionally the display performance was increased.

Installation

Software

If you haven't already, install NodeJS.

Then install the software using: sudo npm install -g rpi-oled

Hardware

Hook up your I2C compatible OLED display to the Raspberry Pi SDL and SCL pins as well as 3.3V power and ground.

Test the software

Run the following command:

rpi-oled writeString -t "Hello World"

This will try to connect to a 128x64 display with address 0x3C on the i2c bus 1, if any of these parameters are not correct for your setup you can change them using the following parameters:

rpi-oled writeString -t "Hello World" -a 0x3F -b "/dev/i2c-0" -w 64 -h 48

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

Command line tools

rpi-oled

The package comes with the rpi-oled command line tool which can be used to display text and graphics on the OLED from the RasPi command line. All functions of the API can be executed using this tool as well.

The tool works similar to oher command line tools like git in that the first parameter of the command is always the command that is to be executed, followed by further parameters. All parameters except the command parameter are always optional.

Available commands

clearDisplay, dimDisplay, invertDisplay, turnOnDisplay, turnOffDisplay, drawPixel, drawLine, fillRect, drawRect, drawBitmap, writeString, startScroll, stopScroll, setCursor

Global parameters

• --width or -w Width of the display in pixel (default 128)
• --height or -h Height of the display in pixels (default 64)
• --address or -a The OLEDs I2C address (default 0x3C)
• --bus or -b The I2C bus to be used (default "/dev/i2c-1")
• --datasize The number of bytes to send via I2C in one go (default 16)
• --microviev Add this parameter if you're using a microview display (default not enabled)
• --noclear or -n Do not clear the display before drawing command (default not enabled)

Command-specific parameters

• --size or -s The font size for text (default 1)
• --text or -t Text to display (default "")
• --x0 or -x X position for drawing (default 0)
• --y0 or -y Y position for drawing (default 0)
• --x1 X1 position for drawing (default 0)
• --y1 Y1 position for drawing (default 0)
• --raduis or -r Radius for circle (default 10)
• --color or -c Color to draw in, 1=white 0=black (default 1)
• --font or -f Font name to use (default "oled-font-5x7")
• --wrapping Enable wrapping for text display (default not enabled)
• --linespacing Line spacing offset for text display (default 0)
• --pixels or -p Pixel data to display in array format (no default)
• --image or -i Path to PNG image to display, will be automatically resized and converted (no default)
• --disable or -d Disable a boolean parameter (no default)
• --direction Direction for scrolling (default "left")
• --start Start position for scrolling (default 0)
• --stop Stop position for scrolling (default 0)
• --help or -? Display help

Examples

rpi-oled writeString -t "Hello World"

rpi-oled drawCircle -x 20 -y 20 -r 10

rpi-oled-status

This utility is meant to be run as a service and displays the Raspberry Pi host name as well as bar graphs for its CPU load, memory load and disk load. It also displays the uptime of the Raspberry Pi.

Parameters

• --width or -w Width of the display in pixel (default 128)
• --height or -h Height of the display in pixels (default 64)
• --address or -a The OLEDs I2C address (default 0x3C)
• --bus or -b The I2C bus to be used (default "/dev/i2c-1")
• --datasize The number of bytes to send via I2C in one go (default 16)
• --microviev Add this parameter if you're using a microview display (default not enabled)
• --updaterate or -u The update rate for the display in milliseconds (default 5000)

Example

rpi-oled-status -a 0x38

Library API

The main part of the package is the library, the API didn't change much from previous forks of this library, below is an overview of the available methods.

The appropriate parameters for the rpi-oled command line tool are listed as well. All parameters except the command parameter are always optional.

API Example

var oled = require('rpi-oled');

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

var oled = new oled(opts);

// do cool oled things here

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
  datasize: 8, // Change the amount of bytes sent at once (default 16)
  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
};

API Overview

clearDisplay

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

Usage:

oled.clearDisplay();

Command line:

rpi-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);

Command line:

rpi-oled dimDisplay or rpi-oled dimDisplay -d to disable dimming

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);

Command line:

rpi-oled invertDisplay or rpi-oled invertDisplay -d to disable dimming

turnOffDisplay

Turns the display off.

Usage:

oled.turnOffDisplay();

Command line:

rpi-oled turnOffDisplay

turnOnDisplay

Turns the display on.

Usage:

oled.turnOnDisplay();

Command line:

rpi-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]
]);

Command line:

rpi-oled drawPixel -p "[[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);

Command line:

rpi-oled drawline --x0 1 --y0 1 --x1 128 --y1 32 -c 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);

Command line:

rpi-oled fillRect --x0 1 --y0 1 --x1 10 --y1 20 -c 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);

Command line:

rpi-oled drawRect --x0 1 --y0 1 --x1 10 --y1 20 -c 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);

Command line:

rpi-oled drawCircle -x 30 -y 10 -r 5 -c 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();
});

Command line:

rpi-oled drawBitmap ./path/to/image.png

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

Command line:

rpi-oled startScroll --direction left --start 0 --stop 15

stopScroll

Stops all current scrolling behaviour.

Usage:

oled.stopscroll();

Command line:

rpi-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);

Command line:

rpi-oled setCursor -x 1 -y 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);

Command line:

rpi-oled writeString -f "oled-font-5x7" -s 1 -t "Hello World" -c 1 --wrapping --linespacing 3 -x 1 -y 1

Note that the rpi-oled tool allows you to combine the setCursor and writeString command by simply supplying x and y parameters.

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();

Command line:

No equivalent