it8951

it8951 is a node.js module written in typescript for the IT8951 e-paper controller. Only tested on the WaveShare e-paper HAT, but should in theory work in other situations.

Update speed

The speed to update the screen is directly linked to the amount of data being transferred. If the update frequency is not quick enough then try to use a lower bits per pixel image.

Hardware compatibility

The package is compatible with any version of Raspberry Pi or similar boards with a BCM2835 chip and tested on a Raspberry Pi 4. It should be compatible with a generic IT8951 setup, but has only been tested on a WaveShare e-paper HAT.

Examples

Displaying an image on the screen requires you to first have written the image to the buffer. In general it's also a good idea to put the display to sleep after you're done as long term usage in the active power state can damage the screen.

async function displayImage(image: Buffer){
    const screen = new it8935(1500); // Change voltage to what is suggested on your e-paper
    screen.run(); // Wake up screen
    await screen.waitForDisplayReady(); // Wait for screen to be ready

    screen.writePixels( // Write to image buffer
        0, // Top corner
        0, // Left corver
        info.width, // Image width, in this case use full screen size
        info.height, // Image width, in this case use full screen size
        image, // Image buffer
        PIXEL_PACKING.BPP8 // Bits per pixel in image
    );
    
    screen.displayArea( // Display from image buffer
        0, // Top corner
        0, // Left corner
        info.width, // Image width, in this case use full screen size
        info.height, // Image width, in this case use full screen size
        mode // Refresh mode
    );

    screen.sleep(); // Put display to sleep
}

There are further examples in the examples directory.

Documentation

Full documentation found here.

License note

This package includes a copy of the C library for Broadcom BCM 2835 by Mike McCauley under open source use. Commercial use requires a license for bcm2835.