View source for E-Paper ESP32 Driver Board

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{{Infobox item
|img=[[File:e-Paper-ESP32-Driver-Board-1.jpg|300px|{{Amazon_nolink|default={{#ifeq: {{#urlget:amazon|0}}|{{#urlget:Amazon|0}}| default|}}|url=link=https://www.waveshare.com/e-paper-esp32-driver-board.htm}}]]
|caption=Universal e-Paper Driver HAT, supports various Waveshare SPI e-Paper raw panels
|category=[[:Category:Expansions|Expansions]], [[:Category:e-Paper|e-Paper]], [[:Category:Raspberry Pi|Raspberry Pi]]
|brand=Waveshare
|{{#ifeq: {{#urlget:amazon|0}}|{{#urlget:Amazon|0}}| default|}}=display
|website_cn=
|website_en=[https://www.waveshare.com/e-paper-esp32-driver-board.htm Waveshare website]
|related=
{{Product List|OLEDs / LCDs/e-Paper}}
}}

<div class="tabbertab" title="Introduction">

= Introduction =
Universal e-Paper Driver HAT, Onboard ESP32, supports various Waveshare SPI interface e-Paper raw panels. Supports refreshing image to e-paper via WIFI or Bluetooth. It also supports Arduino.
{{Amazon|{{#ifeq: {{#urlget:amazon|0}}|{{#urlget:Amazon|0}}| default|}}=display
|More = [https://www.waveshare.com/e-paper-esp32-driver-board.htmm More]}}

==Parameter==
*WiFi Standard: 802.11b/g/n
*Communication Interface: SPI
*Bluetooth Standard: 4.2, BR/EDR and BLE included
*Communication Interface: 3-Wire SPI, 4-wire SPI (default)
*Working voltage: 5V
*Working Current: 50mA-150mA
*Outline dimension: 29.46mm x 48.25mm
 
==Pin==
{|class="wikitable" 
!Pin !! ESP32 !! Description 
|- 
|VCC||3.3V||Power input 
|- 
|GND||GND||Power ground 
|- 
|SCK||P13||SPI CLK, Clock Signal Input 
|- 
|DIN||P14||SPI MOSI, Data Input
|- 
|CS||P15||Chip Select, active-low
|- 
|BUSY||P25||Busy Output Pin (means busy)
|- 
|RST||P26||Reset, active-low
|- 
|DC||P27||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 ESP32, support Arduino development
*Provide 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 dithering algorithm for more color combinations and better shadow 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, can be powered by lithium battery
*Provide complete supporting information manual

==Application==
This product cooperates with the ink screen and is suitable for the application scenario of wireless brushing.
*Supermarket electronic price tag
*Electronic name card
*Serial information display board, etc.

=Preparation=
{{E-paper setup}}
*Turn on the serial port module: Toggle the No. 2 switch to "ON", this switch controls the power supply of the CP2102 (USB to UART module). When you don't need to use it, you can manually turn off the module to save power (if the switch 2 is in the OFF state, you cannot upload the program)<br/>
*Use a micro USB cable to connect the ESP32 driver board to a computer or 5V power supply<br/>
==Download Demo==
We provide three kinds of demos: local, bluetooth, and WiFi. The sample program can be found in the "Information" tab of this page, or click the sample program to download<br/>
Unzip the downloaded compressed package, you can get the following files:[https://{{SERVERNAME}}/w/upload/5/50/E-Paper_ESP32_Driver_Board_Code.7z demo example]<br/>
[[File:esp32 download de.png]]<br/>
*ePape_Esp32_Loader_APP: Bluetooth App source code (Android Studio)<br/>
*examples: local demo<br/>
*Loader_esp32bt: Bluetooth demos<br/>
*Loader_esp32wf: WiFi demo<br/>
*app-release.apk: Bluetooth routine App installation package<br/>
==Environment Configuration==
*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.<br/>
Official link: https://www.arduino.cc/en/Main/Software<br/>
'''Download the ESP32 Dev Module management tool:'''
1. Open the preferences of the arduino software and add a link to the add-on board manager URL: https://dl.espressif.com/dl/package_esp32_index.json
<br/>
[[File:esp32 dev.png]]<br/>
After the addition is complete, open Tools -> Development Board -> Development Board Management Tool, and manually search for "ESP32" to download and install the latest version.<br/>
[[File:esp32 install.png]]<br/>
3. After the installation is complete, you can find the model option of ESP32 Dev Module in Tools - Boards of IDE.<br/>
[[File:ide.png]]<br/>
If the installation cannot be completed due to repeated errors, please contact the after-sales technicians.<br/>
==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<br/>
[[File:colorscale.png]]<br/>
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.<br/>
[[File:colordoth.png]]<br/>
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<br/>
[[File:colordoth2.png]]<br/>

==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 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 routine 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<br/>
[[File:dither.png]]<br/>
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 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.<br/>
===Comparison===
Original image<br/>
[[File:Girl.png]]<br/>
"Black and white grading" and "Multicolor grading"<br/>
[[File:gr.png]]<br/>
"Black and White Dithering" and "Multicolor Dithering"<br/>
[[File:blgirl.png]]<br/>
=Bluetooth Examples=
{{ESP32 e-Paper BT-Example}}

=WiFi Examples=
{{ESP32 e-Paper WiFi-Example}}

= Offline Examples=
{{ESP32 e-Paper Offline-Example}}

= Resources=
== Documentation ==
* [https://www.waveshare.com/w/upload/8/80/E-Paper_ESP32_Driver_Board_Schematic.pdf Schematic]

== Demo Code ==
*[[:File:E-Paper_ESP32_Driver_Board_Code.7z| 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.
*[https://forum.arduino.cc/index.php?topic=487007.0 Waveshare e-Paper display with SPI]

=FAQ=
{{FAQ|If you don't have a V2 logo on the back of your 2.13inch e-paper screen, how do I use it?|
* Open epd1in13.h in the project and change the following value to 1
[[File:epd2in13_esp_chose.png|400px]]
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{{FAQ|For the new version of the ESP32 Driver Board, what are the functions of the above two DIP switches?|
* Set the model: Set the No. 1 switch according to the E-Paper model you are using. There are many models of the E-Paper. If the model you used is not listed, please use ‘A’ first to try.
[[File:ESP32_SWITCH.png|900px]]

*Turn on the serial port module: Turn the No. 2 switches to "ON", this switch controls the power supply of the CP2102 (USB to UART module). When you don’t need to use it, you can manually turn off the module to save power (if the No. 2 switch is in the OFF state, the device cannot upload the program)
[[File:Epd_esp32_hard_30.png|700px]]
||}}

==Support==
{{Service00}}
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[[Category:Expansions|Expansions]] [[Category:e-Paper|e-Paper]] [[Category:Raspberry Pi|Raspberry Pi]]