Resources

Documentation

• Schematic
• User Manual
• ESP32 datasheet

Demo Code

• Sample demo

Software Driver

CP2102 (Old version, used before July 2022)

• CH343 VCP driver for Windows
• CH343 driver for MacOS
• MacOS guide

CH343 (New version, used after July 2022)

• Windows VCP driver
• MAC driver

Related Resources

• ESP32 Resouces
• E-Paper Floyd-Steinberg
• Zimo221
• Image2Lcd Image Modulo
• Image Modulo

Note

This Wiki mainly introduces the specific operation of this product, if you want to get the product support ink screen models please go to the bottom of the official website product details to get.

Note: The corresponding demo only takes the latest version of the screen as an example, if you are using an older version, please refer to the version label on the back of the screen.

Overview

Version Guide

20220728: The serial port chip is changed from CP2102 to CH343, please pay attention to the driver selection.

Introduction

Universal e-Paper Driver HAT features ESP32 and supports various Waveshare SPI interfaces in e-Paper raw panels. It also supports refreshing images to e-paper via WIFI or Bluetooth and Arduino.

Parameter

• WiFi Standard: 802.11b/g/n
• Communication Interface: SPI/IIC
• Bluetooth Standard: 4.2, BR/EDR, and BLE included
• Communication Interface: 3-Wire SPI, 4-wire SPI (default)
• Operating Voltage: 5V
• Operating Current: 50mA-150mA
• Outline Dimensions: 29.46mm x 48.25mm
• Flash Size: 4 MB
• SRAM Size: 520 KB
• ROM Size: 448 KB

Pin

PS: The above is the board fixed connection, with no additional operation by the user.

Feature

• Onboard ESP32, support Arduino development.
• Provide an Android mobile APP program, which can update the display content through Bluetooth EDR, easy to use.
• Provide HTML host computer program, which can remotely update the display content through the web page, which is convenient to integrate into various network applications.
• Supports Floyd-Steinberg's dithering algorithm for more color combinations and better shadows of the original image.
• Supports many common image formats (BMP, JPEG, GIF, PNG, etc.).
• Factory built-in e-ink screen driver (open source).
• 5V pin supports 3.6V to 5.5V voltage input and can be powered by a lithium battery.
• Comes with online resources and manuals.

Application

This product cooperates with the ink screen and is suitable for the application scenario of wireless refreshing.

• Supermarket electronic price tag
• Electronic name card
• Serial information display board, etc.

Preparation

Hardware Connection

This product is shipped with an ESP32 network driver board, an adapter board, and an FFC extension cable.
When using it, you can directly connect the screen to the driver board, or connect it through extension cables and adapter boards.
Direct access to the driver board:

Access via extension cord:

• Set the mode switch: Set the No. 1 switch according to the model of the EPD used. There are many screens. If it is not listed, please use 'A' to try. If the display effect is poor or cannot be driven, please try switching the switch.

• Turn on the serial port module: Toggle the No. 2 switch to "ON", this switch controls the power supply of the USB to the UART module. When you don't need to use it, you can manually turn off the module to save power (if switch 2 is in the OFF state, you cannot upload the program.)
  

• Use a micro USB cable to connect the ESP32 driver board to a computer or 5V power supply.
  

Download Demo

We provide three kinds of demos: local, Bluetooth, and WiFi. The sample program can be found in #Resources, or click the sample demo to download.
Unzip the downloaded compressed package, you can get the following files:

• ePape_Esp32_Loader_APP: Bluetooth App source code (Android Studio)
  
• examples: local demo
  
• Loader_esp32bt: Bluetooth demos
  
• Loader_esp32wf: WiFi demo
  
• app-release.apk: Bluetooth demo App installation package
  

Environment Configuration

• Arduino ESP32/8266 Online Installation

Image Processing Algorithms

In the Bluetooth and WiFi demos, two image processing algorithms are provided, namely Level and Dithering.

Color scale method

An image can be divided into several large color gamuts, and each pixel on the image is divided into these color gamuts according to how close the color is to these color gamuts. This method is more suitable for images with few colors, such as bright or tri-color shapes or text images. Taking the black and white and red ink screen as an example, when processing the image, we hope to process it into black, white, and red, so for an image, we can divide all the colors of the image into three large color areas: the black area, white area, red area.
For example, according to the figure below, if the value of a pixel in the grayscale image is equal to or less than 127, we regard this pixel as a black pixel, otherwise, it is white.

For color images, we all know that RGB has three color channels. Compared with the red channel, we can refer to blue and green as the blue-green channel or the non-red channel. According to the figure below, a pixel on a color image, if it has a high value in the red channel, but a low value in the blue-green channel, we classify it as a red pixel; if its red channel and blue- If the green channel has low values, we classify it as a black pixel; if the red and blue-green channel values are high, we classify it as white.

In the algorithm, the color definition is calculated based on the difference between the RGB value and the sum of the squares of the expected color value. The expected color value refers to the color value that the pixel is closest to, and these values are stored in the curPal array.

Dithering

For those images with more colors or more gradient areas, the above gradation method is not suitable. In many cases, the pixels in the gradient area in the image may be very close to all color gamuts. If you use the gradation method to draw The image will lose a lot of image details. Many images are taken by cameras, by mixing colors to paint shadows and transition areas, in these images, the gradient area accounts for the majority. For the human eye, it is easy to confuse a particularly small color. For example, two colors, red and blue, are juxtaposed. If you reduce it to a small enough hand, it will appear to the human eye as a mixture of red and blue. into color. The defect of the human eye means that we can deceive the human eye and use the "mixing" method to obtain more colors that can be expressed. The dithering algorithm uses this phenomenon. The demo we provide uses the Floyd-Steinberg dithering algorithm - based on error diffusion (published by Robert Floy and Louis Steinberg in 1976). The formula is for error diffusion according to the image below:

X is the error (a scalar (vector) difference between the original color and the gray value (color value)), this error will spread to the right, lower right, lower, and lower left in four directions, respectively 7/16, 1/16, 5/16 and 3/16 weights are added to the values of these four pixels. Interested users can go to understand the algorithm, there are many resources on the Internet.

Comparison

Original image

"Black and white grading" and "Multicolor grading"

"Black and White Dithering" and "Multicolor Dithering"

Bluetooth Demo

Download example

• Go to the Loader_esp32bt directory, double click the Loader_esp32bt.ino file to open the example.
• Choose Tools -> Boards -> ESP32 Dev Module and select the correct Port according to Device Manager: Tools -> Port.

• Click the Upload icon to build the project and upload it to the ESP32 driver board.
• Install the APP to the Android board and open it:

• APP has five buttons on the main page:
  • BLUETOOTH CONNECTION: This button is used to connect the ESP32 device via Bluetooth.
    
  • SELECT DISPLAY TYPE: This button is used to select the type of display according to what you buy.
    
  • LOAD IMAGE FILE: Click it and choose a picture to open. It is only available after choosing the display type.
    
  • SELECT IMAGE FILTER: This button is used to choose the image process method.
    
  • UPLOAD IMAGE: Upload the processed image to the ESP32 driver board and update to e-Paper display.
    
• Please first open the Bluetooth function of your phone. Click the BLUETOOTH CONNECTION button -> Click the SCAN icon on the top-right to scan the Bluetooth device.
• Find the ESP32 device and connect. If your phone is the first time to connect this device, it requires pairing, complete the pairing process according to the prompt. (Note: The APP cannot work with pairing.)
• Click "SELECT DISPLAY TYPE" to choose the display type.
• Click "LOAD IMAGE FILE" To choose a picture from your phone and cut it.
• Click " SELECT IMAGE FILTER" to choose a process algorithm and confirm.
  • "LEVEL: MONO": This option will process the picture to a monochrome image.
  • "LEVEL" COLOR": This option will process the picture to the tricolor image according to the display colors of the display (only valid for colorful displays).
  • "DITHERING: MONO": This option will process the picture to a monochrome image.
  • "DITHERING: COLOR": This option will process the picture to the tricolor image according to the display colors of the display (only valid for colorful displays).
• Click "UPLOAD IMAGE" to upload the image to the ESP32 device and display it.

Documentation

• Schematic
• User Manual
• ESP32 datasheet

Demo Code

• Sample demo

Software Driver

CP2102 (Old version, used before July 2022)

• CH343 VCP driver for Windows
• CH343 driver for MacOS
• MacOS guide

CH343 (New version, used after July 2022)

• Windows VCP driver
• MAC driver

Related Resources

• ESP32 Resouces
• E-Paper Floyd-Steinberg
• Zimo221
• Image2Lcd Image Modulo
• Image Modulo

To：

Dear Customers, There may be a lag of several hours before we could process your order, depending on the time difference between your location and ours. Sincerely hoping your understanding!

Email(support)

services01@spotpear.com