Node.js library for easily creating an ePaper display on a Raspberry Pi using HTML and Javascript.
ePaper.js can be used as:
- A command line application for single step rendering of a URL onto an ePaper display
- A library that can interface ePaper displays with custom Node.js applications
Features include:
- Supports multiple ePaper Displays
- High performance, native c++ hardware access
- Multiple color modes: black / white, grayscale, black / white / red
- Dithering for black / white images
Usage
ejs <command> [options] <deviceType>
For example, the following command will update the Waveshare 7.5" v2 screen with the contents of http://localhost:8080 every 10 minutes.
ejs refresh rpi-7in5-v2 "http://localhost:8080"
For available devices types, see supported hardware. The different commands and suggested workflows are described below.
Commands
Display: display a single rendition of a URL
ejs display [options] <deviceType> <url>
| Option | Description | Allowed Values |
|---|---|---|
-o / --orientation |
Use (h)orizontal or (v)ertical orientation | [h, v] |
-c / --colorMode |
Desired color mode | [black, 4gray, red] |
--screenshotDelay |
Wait an additional amount of time after loading the URL before displaying. Useful for client side apps | Time in milliseconds |
--dither |
Use a dithering algorithm to approximate grayscale / mid-tones on black and white displays | |
--username |
Username for basic authentication | username as string |
--password |
Password for basic authentication | password as string |
--debug |
Print additional log info and stacktraces | |
--version |
Show version number | |
--help |
Show help |
Refresh: continuously update and display the URL
ejs refresh [options] <deviceType> <url>
| Option | Description | Allowed Values |
|---|---|---|
-i / --interval |
Amount of time between refreshes | Time in seconds (default 10 min) |
-o / --orientation |
Use (h)orizontal or (v)ertical orientation | [h, v] |
-c / --colorMode |
Desired color mode | [black, 4gray, red] |
--screenshotDelay |
Wait an additional amount of time after loading the URL before displaying. Useful for client side apps | Time in milliseconds |
--dither |
Use a dithering algorithm to approximate grayscale / mid-tones on black and white displays | |
--username |
Username for basic authentication | username as string |
--password |
Password for basic authentication | password as string |
--debug |
Print additional log info and stacktraces | |
--version |
Show version number | |
--help |
Show help |
Clear: clear the display
ejs clear [options] <deviceType>
| Option | Description | Allowed Values |
|---|---|---|
--debug |
Print additional log info and stacktraces | |
--version |
Show version number | |
--help |
Show help |
Workflows
Self-Hosting
- Create a web app and store it on your Raspberry Pi
- Host the web app with http-server
- Run ePaper.js with
ejs refresh <deviceType> "http://localhost:8080" (or whatever port you configure http-server to run on)
Cloud Hosting
- Create a web app and host it on a service like GitHub Pages or Netlify
- Run ePaper.js with
ejs refresh <deviceType> "<URL of your app>"
Running As a Daemon
There are several methods of automatically launching ePaper.js on startup and restarting in case of failures
- Run with pm2
- Create a systemd service
Example Applications
See the examples directory
- weather-station: This creates an example weather station display
- color-test: Used to test the various color modes
- 4gray: A demonstration of the 4gray capabilities
- dithering: A demonstration of the dithering feature
Supported Software Versions
The following versions are the recommended versions that using during development and testing. Other versions may work, but are not officially supported.
- Node.js:
16 LTS - Raspberry Pi OS:
Bullseye 32 / 64bit - Chromium:
104.0.5112.105
Installation
Raspberry PI
Enable SPI
sudo raspi-config
# Choose Interfacing Options -> SPI -> Yes to enable SPI interface
sudo rebootInstall Node The official recommendation by Node.js is to install Node with a package manager. This helps ensure you'll have the latest LTS version and the proper permissions to install global packages. ePaper.js recommends using nvm
Raspberry Pi 2, 3, 4 Zero 2:
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.1/install.sh | bash source ~/.bashrc nvm install 16
Raspberry Pi 1, Zero:
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.1/install.sh | bash source ~/.bashrc NVM_NODEJS_ORG_MIRROR=https://unofficial-builds.nodejs.org/download/release nvm install 16
Install Dependencies
sudo apt-get update sudo apt-get install -y build-essential chromium-browser
Install ePaper.js
Globally install the @epaperjs/cli command line app and the appropriate package for your screen (See supported hardware).
For example, to install ePaper.js for the Waveshare 7.5" V2 Screen:
npm install --global @epaperjs/cli @epaperjs/rpi-7in5-v2
Supported Hardware
| Device | Device Type | npm Package | Color Modes |
|---|---|---|---|
| Waveshare 4.2" | rpi-4in2 |
@epaperjs/rpi-4in2 |
black 4gray |
| Waveshare 7.5" v2 | rpi-7in5-v2 |
@epaperjs/rpi-7in5-v2 |
black |
| Waveshare 3.7" hat | rpi-3in7 |
@epaperjs/rpi-3in7 |
black, 4gray |
| Waveshare 2.13" hat v2 | rpi-2in13-v2 |
@epaperjs/rpi-2in13-v2 |
black, red |
| Waveshare 2.13" bc | rpi-2in13-bc |
@epaperjs/rpi-2in13-bc |
black |
| Waveshare 2.7" | rpi-2in7 |
@epaperjs/rpi-2in7 |
black |
Adding Support For Additional Displays
It's easy to extend ePaper.js to support additional Waveshare devices. Displays from other manufacturers should be possible to support as well, as long as there is a C / C++ driver available.
If you would like to request support for another display, please open an issue with the title 'Add support for <Device Make \ Model>'. If you're a developer and have extended support yourself, put up a pull request!