Template: Pico e-Paper 4.2 Spec

Overview

This is a 4.2inch e-Paper display module for Raspberry Pi Pico, 400x300 pixels, support black, white, and 4 grayscale display, SPI interface.

No backlight, keeps displaying last content for a long time even when power down
Ultra-low power consumption, basically power is only required for refreshing
SPI interface, requires minimal IO pins
Onboard voltage translator, compatible with 3.3V / 5V MCUs
2x user buttons for easy interacting

We define the pixels in a monochrome picture, 0 is black and 1 is white.
White：□，Bit 1
Black：■：Bit 0

The dot in the figure is called a pixel. As we know, 1 and 0 are used to define the color, therefore we can use one bit to define the color of one pixel, and 1 byte = 8pixels
For example, If we set first 8 pixels to black and the last 8 pixels to white, we show it by codes, they will be 16 bit as below:

For computer, the data is saved in MSB format:

So we can use two bytes for 16 pixels.

In addition to bicolor displaying, the 3.7inch e-Paper also supports four grayscale.

To display grey pixels, we need to define data for gray

The display divides a four-grayscale picture into two pictures. The pixels in the same position of pictures are combined into one pixel.

With the tables above, you can define the data which can be used to display grayscale pixels in the 3.7inch e-Paper