E-Paper ESP8266 Driver Board

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E-Paper ESP8266 Driver Board
E-Paper-ESP8266-Driver-Board-1.jpg

Universal e-Paper Driver HAT, supports various Waveshare SPI e-Paper raw panels
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Introduction

F-Paper ESP8266 Driver Board can read picture from PC or phone by WiFi and display the information. It also supports Arduino.

Parameter

  • WiFi standard: 802.11b/g/n
  • Interface port: 3-wire SPI、4-wire SPI(default)
  • Operating voltage: 5V
  • Operating current: 50mA ~ 100mA
  • Outline dimension: 29.57mm x 48.26mm
  • Hole diameter: 2.9mm

Pin

Pin ESP8266 Description
VCC VCC 3.3V Power input
GND GND Power ground
SCK GPIO14(D5) SPI CLK, Clock Signal Input
DIN GPIO13(D7) SPI MOSI, Data Input
CS GPIO15(D8) Chip Select, active-low
BUSY GPIO5(D1) Busy Output Pin (means busy)
RST GPIO2(D4) Reset, active-low
DC GPIO4(D2) Reset, Data/Demand, low level means to demand, high level means data

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

Feature

  • Onboard ESP8266, support Arduino development
  • Provide HTML host computer program, can update content remotely through web page, easy to integrate into various network applications
  • Supports Floyd-Steinberg dithering algorithm for more color combinations and better shadow rendering of the original image
  • Supports a variety of common image formats (BMP, JPEG, GIF, PNG, etc.)
  • Built-in e-ink screen driver (open source)
  • Provide complete supporting information manual

Application

This driver board works with the Micro Snow E-ink screen, which can be applied to the wireless update of electronic tags

  • Electronic price tags in supermarkets
  • Information labels for customer service windows, such as name labels
  • Small advertising label

Preparation

Download examples

Two examples were provided for the display, WiFi example and the offline example. You can find the archive in Resources tabber. Or directly download the link here to download
Unzip the arvhive and you will get the following examples:
Epd esp8266 download 1.png

  • examples:Offline example
  • Loader_esp32wf:WiFi Example

Setup Arduino IDE

  • If the Arduino IDE is not installed on your computer before, or the version of the IDE is older. It is recommended to go to the Arduino official website to download the latest IDE and install it according to your own system. Link:https://www.arduino.cc/en/Main/Software
  • Open the IDE and choose File->Preferences and add the link to the Additional Boards Manager URLs box:
http://arduino.esp8266.com/stable/package_esp8266com_index.json and then click toOK(GitHub domestic access is relatively slow, it is recommended to use a search engine to complete this step)

Epd esp82661.png

  • Open Tools -> Boards -> Boards Manager, find the ESP8266by ESP8266 Community, and install it

Epd esp82662.png

  • After installing, you can find the NodeMCU 1.0 option in Tools - Boards of Arduino IDE Menu.
  • Set up the model switch, and set the model switch according to the ink screen model used (if the display effect is poor or cannot be driven, please try to switch the switch)

Epd esp8266 hardware.png

Trigger state E-Paper
A 1.54 inch, 2.13 inch, 2.9 inch
B 1.54 inch(b), 2.13 inch(b), 2.7 inch, 2.7 inch(b), 2.9 inch(b), 4.2 inch, 4.2 inch (b), 7.5 inch(b), 7.5 inch(b)

Image Process Algorithm

In the Bluetooth example and the WiFi example, we use two kinds of Image algorithms, Level and Dithering.

Level

An image can be divided into several large color gamuts. Each pixel on the image is classified into the corresponding color gamuts according to how close the color is to these color gamuts. This method is more suitable for images that have few colors, such as bright or three-color shapes or text images. Take the black, white and red ink screen as an example. When processing the image, we hope to process it into black, white, and red. Therefore, for an image, we can divide all the colors of the image into three color areas: black area, white area, and red area.
For example, according to the figure below, if the value of a certain pixel in the grayscale image is equal to or less than 127, we regard this pixel as a black pixel, otherwise, it is white
Epd esp32 lever 1.png
As we know, color images have three color channels called RGB. Compared with the red channel, we can collectively call blue and green the blue-green channel or the non-red channel. According to the figure below, if a pixel on a color image has a high red channel value but a low blue-green channel value, we classify it as a red pixel; if the value of both the red and blue-green channels are very low, we classify it as a black pixel; if the values of the red and blue-green channels are both high, we classify it as white.
Epd esp32 lever 2.png
In the algorithm, the color definition is calculated based on the difference between the RGB value and the sum of 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.
Epd esp32 lever 3.png

Dithering

For images with more colors or more gradient areas, the above color scale 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 Level method, the image will lose a lot of image details. Many pictures taken by cameras use the method of mixing colors to draw shadows and transition areas. In these images, the gradual area accounts for most of them.
For the human eye, it is easy to confuse very small colors. For example, set two colors red and blue side by side, if it is reduced to a small enough size, it will become a mixture color of red and blue to the human eye. 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 Floyd-Steinberg algorithm is based on the error diffusion method(published by Robert Floy and Louis Steinberg in 1976). The formula is based on the error diffusion of the image below
Epd esp32 dithering 1.png
X is the error (a scalar (vector) difference between the original color and the gray-scale value (the color value)), and the error spreads to the right, bottom right, bottom, and bottom left, adding weights of 7/16, 1/16, 5/16, and 3/16, respectively, to the values of the four pixels. If you are interested in the algorithm, you can search online for more resources

Expected result of two methods

Original picture

Epd esp32 compare 1.png

"Black/White-Level" and "Colors-Level"

Epd esp32 compare 2.png Epd esp32 compare 2-2.png

"Black/White-Dithering" and "Colors-Ditherring"

Epd esp32 compare 3.png Epd esp32 compare 3-2.png

How to Use

  • Go to the Loader_esp32wf directory, double click Loader_esp32wf.ino file to open the project.
  • Choose Tools->Boards->ESP32 Dev Module in IDE menu, and select the correct COM port:Tools->Port

Epd esp32 wifi 1.png

  • Open the srvr.h file, modify the ssid and password to your actual WiFi used.

Epd esp32 wifi 2.png

  • Click the Upload icon to build the project and upload it to the ESP32 driver board.
  • Open the serial monitor, set the baud rate to 115200. Then you can get the information printed like the IP of the ESP32 board.

Epd esp32 wifi 3.png

  • Open a browser on the PC or mobile phone (Note that you should connect your PC/Phone to the same network as the ESP32 board), go to the webpage with the IP address of the ESP32 board:

Epd esp32 wifi 4.png

  • There are five areas in the webpage:
    • Image Operation
      Select Image file: Click the option to choose a picture from PC/phone

Level: mono: Black/White image level processing.
Level: color: Colorful image level processing (only valid for colorful display)
Dithering: mono: Black/White image Dithering processing
Dithering: color: Colorful image Dithering processing (only valid for colorful display)
Update image: Upload image to ESP32 board and display it.

    • IP Information: In this are, the IP information of the ESP32 board connected is listed.
    • Image Size Setting: x and y is the beginning position on the image. For example, if you select an image with 800x480 resolution, and the display you connect is the 2.13. The 2.13inch display cannot display the whole picture, the codes will crop the picture according to the resolution of displays. If you set the x and y, the codes will set the (x, y) as the being pixel where it starts to crop. w and h is the resolution of the displays choose.

Note: If you modify the x and y value, you need to click the Level or Dithering options to process the image again.

    • Display Type: You should first select the display size here according to the display used.
    • Image Preview: it will display the original image selected and the image processed.
    • PS: The upload progress value is printed at the bottom of the webpage when uploading.

For examples:

  • In area ① click Select image file to choose a picture, you can also drag the picture to the Original image area directly.
  • In area ④ choose the type according to the display, for example 1.54b
  • In area ① choose an algorithm to process the image, for example Dithering: color
  • In area ① click Upload image to upload the image and display.

Epd esp32 wifi 5.png

Download example

  • Go to examples\ directory. copy the whole esp8266-waveshare-epd folder to [Installation directory of Arduino %LOCALAPPDATA%\Arduino15\packages\esp8266\hardware\esp8266\2.7.1\libraries, Where "2.7.1" needs to be changed according to the installed ESP8266 support package version

Epd esp8266 example 1.png

  • Open the Arduino IDE, Find the wareshare-e-Paper examples from File->Example, and select one according to the display type.

Epd esp8266 example 2.png

Resources

Documentation

Demo Code

Related Resources

This is a post in Arduino Form about our SPI e-Paper thanks to ZinggJM, maybe you want to refer to.

FAQ

 Answer:
  • Open epd1in13.h in the project and change the following value to 1

Epd2in13 esp chose.png


Support