WeAct Epaper 4.2" screen with ESP32-S3 not working

Other Hardware Displays
1

Hi, I'm new in the world of microcontrollers and the thing is that after many hours of searching, I still haven't solved my problem. No matter how much I try different pins, the screen shows no signs of it working.

I am using an ESP32-S3-WROOM-1 with the WeAct Epaper 4.2" model.
Arduino IDE and board type "ESP32 S3 Dev".

I have been testing the GPIO pins of the ESP32 with leds, and it worked fine.
To test the screen, I used the provided example from the manufacturer with GxEPD2 library.

photo_2025-01-23_15-51-16
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Just modifying these lines like this.

// ESP32 CS(SS)=37,SCL(SCK)=36,SDA(MOSI)=35,BUSY=3,RES(RST)=9,DC=38

// 4.2'' EPD Module
GxEPD2_BW<GxEPD2_420_GDEY042T81, GxEPD2_420_GDEY042T81::HEIGHT> display(GxEPD2_420_GDEY042T81(/*CS=5*/ 37, /*DC=*/ 38, /*RES=*/ 8, /*BUSY=*/ 3)); // 400x300, SSD1683

I assume the screen uses a SPI interface, but I'm not sure.

photo_2025-01-23_15-46-57
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photo_2025-01-23_15-47-02
photo_2025-01-23_15-47-021280×750 90.8 KB

2

Hello,
Having same issue in same setup ESP32-S3-WROOM-1 with the WeAct Epaper 4.2" model.
Arduino IDE and board type "ESP32 S3 Dev"
Try to change pinout refering to ESP32-S3-WROOM-1 devkit using SPI pins.

image
image1440×773 164 KB

Working well for me with this

//ESP32 CS(SS)=10,SCL(SCK)=12,SDA(MOSI)=11,BUSY=15,RES(RST)=2,DC=0
// 4.2'' EPD Module
GxEPD2_BW<GxEPD2_420_GDEY042T81, GxEPD2_420_GDEY042T81::HEIGHT> display(GxEPD2_420_GDEY042T81(/*CS=5*/ 10, /*DC=*/ 0, /*RES=*/ 2, /*BUSY=*/ 15)); // 400x300, SSD1683
3

:smiley: It worked at first try. Thank you, thank you, thank you.

But I don't finish to understand why the image indicates that GPIO 8 and 9 are for SDA and SCL, but it only works with 11 and 12.

I imagined that the problem would be related to what pins to use, but how I don't understand what many things mean. Again thanks you for answering.

4

Nice and you're welcome !
Yes it's confusing because SDA and SCL are most likely used for I2C communication (it's the case from Devkit view, pin8/9 are I2C). Controller chip of this display (SSD1683) use "SDA/SCL" in datasheet instead of MOSI/SCK (terminaison used for SPI). But since you found a chip select (CS) you can assume it's realy SPI and not I2C.
Have fun with your display :wink: