Help Needed with Waveshare 7.5" E-Ink Display (Rev 2.3 HAT) and ESP32

[joshbear01]

Hi all,

I’ve been trying to get a Waveshare 7.5" E-Ink Display (Rev 2.3 HAT) working with an ESP32 WROOM Development Board (specifically the DIYMORE ESP32 WROOM with Type C and CP2102 chip), but I’ve hit a roadblock (understatement!). I’m hoping someone here can help troubleshoot or point me in the right direction. Apologies for all the info. I didn't know how much to post.

I’m a complete newbie to all of this and just want to build a functioning weather display, but I can’t get the screen to work. I’ve tried three ESP32 modules and two screens with three Hats , so I don’t think this is a hardware issue. Here’s a detailed summary of what I’ve done so far (I’ve been using ChatGPT as well)

Hardware Setup

1. E-Ink Display :

• Waveshare 7.5" E-Ink Display Rev 2.3 HAT.

• Sticker on the rear of the screen says: 075BN-T7-D2 .

• Resolution: 800x480 .

2. Controller Board :

• DIYMORE ESP32 WROOM with Type C and CP2102 chip.

• Voltage: 3.3V logic , powered via USB.

3. Connections :
The Waveshare HAT (rev 2.3) is connected to the ESP32 as follows:

- VCC → VIN (5V)

- PWR → 3.3V

- GND → GND

- DIN → GPIO 23 (MOSI)

- CLK → GPIO 18 (SCK)

- CS → GPIO 5

- DC → GPIO 16

- RST → GPIO 4

- BUSY → GPIO 21

4. Power Supply :

- Verified voltages using a multimeter:

- VCC (VIN / 5V): 5.06V .

- PWR (3.3V): 3.217V .

Steps Taken

Initial Tests

1. Verified the BUSY pin with a simple sketch:

• At times, the BUSY pin was stuck HIGH , and at other times, it was stuck LOW .

• Inconsistent behaviour raises concerns about proper communication or initialization.

2. Uploaded a test sketch to confirm basic ESP32 functionality:

• A simple blink sketch worked, confirming that the ESP32 is operational.

Using GxEPD2 Library

1. Used the GxEPD2 library with the following driver configurations:

• GxEPD2_750_T7 : GDEW075T7 800x480, EK79655 (GD7965).

• GxEPD2_750_GDEY075T7 : GDEY075T7 800x480, UC8179 (GD7965).

2. Sample sketches compiled and uploaded successfully, but:

• The Serial Monitor logs indicate the initialization process completes.

• The screen remains blank.**

• No obvious hardware faults or errors.

Using Waveshare Example Code

1. Tried the Waveshare-provided example code from their wiki for the 7.5" E-Ink Display .

• Modified the code to use the ESP32’s pins as listed above.

• Fixed compatibility issues (e.g., replacing avr/pgmspace.h with pgmspace.h).

• Code compiled and uploaded successfully, but:

• The screen remained blank.

The Serial Monitor displayed Initializing e-Paper Display... and then stopped.

2. Added debugging logs to the initialization sequence in the Waveshare library.

• The initialization appears to proceed, but no updates are visible on the screen.

What I Know

1. Power and Connections

• Verified power levels and wiring multiple times using a multimeter.

• All voltages are correct ( 5.06V for VIN , 3.217V for 3.3V ).

2. Display Behavior :

• The screen does not respond or update.

• At one point during testing, a black border briefly appeared on the screen , but this behavior has not been reproducible.

3. Hardware :

• The ESP32 and HAT appear functional based on blink sketches and Serial Monitor output.

Questions for the Community

1. Driver Confusion :

• Based on the sticker model ( 075BN-T7-D2 ) and resolution ( 800x480 ), which driver should I use in the GxEPD2 library or the Waveshare examples ?

2. Initialization Issues

• The display initializes without errors in code, but the screen remains blank. What additional steps can I take to confirm the display is receiving commands?

3. Power Configuration :

• Am I wiring VCC → VIN (5V) and PWR → 3.3V correctly for the Waveshare Rev 2.3 HAT and this screen size?

4. Other Suggestions :

• Are there additional tests I can run to isolate the problem?
• Is this screen compatible with the ESP32 I’m using?

Hardware Links
waveshare screen

Waveshare 7.5 inch E-Paper Display HAT V2 for Home Assistant & ESPHome...

[DIYMORE ESP32 WROOM](diymore 3PCS ESP32 WROOM Development Board Type C,ESP32 WIFI Module with CP2102 WLAN WiFi Bluetooth ESP32 WROOM : Amazon.co.uk: Computers & Accessories

Any guidance or suggestions would be greatly appreciated. Let me know if you need additional details!

Thanks in advance!

[silentobserver]

I would expect the display to be a GDEY075T7. But you should try both.

For use with 3.3V processor you should connect VCC to 3.3V, for the level converter to work with the correct voltage (HIGH/LOW) detection, and to not provide 5V to the BUSY pin on the processor.
Good Luck!

Did you adapt the constructor parameters to your wiring?
change this:

GxEPD2_DISPLAY_CLASS<GxEPD2_DRIVER_CLASS, MAX_HEIGHT(GxEPD2_DRIVER_CLASS)> display(GxEPD2_DRIVER_CLASS(/*CS=5*/ EPD_CS, /*DC=*/ 17, /*RST=*/ 16, /*BUSY=*/ 4)); // my suggested wiring and proto board

[joshbear01]

Thanks. will give that a try. As regards the pwr and VCC lines from the hat. I should switch those over so VCC goes to the 3.3V and pwr goes to 5V/vin. Is that correct?
Thanks again
Josh

[silentobserver]

PWR is a control line. For VCC 3.3V it should also be 3.3V.
But maybe it doesn't matter. See schematics.

[joshbear01]

Update. IT'S ALIVE! you were right both PWR and VCC need to go to the 3v3 pin. Also my esp32 board Had two pins labelled G23. instead of one being called G33. I noticed because I opened a new board and saw it had 2 G33 pins and no G23 pins!

Hands up it was my daughter who noticed it! She is now unbearably smug.

Thanks again for the help.
Josh