Wemos- HAT - WaveShare GxGDEW075Z09 - No connection to wemos

I trying for several hours the example GxEPD_SPI_TestExample.ino with WaveShare Display 7,5 inch b/w/r and HAT Interface to Wemos D1. Wireing as recommended in Sketch for Wemos
// mapping suggestion from Waveshare SPI e-Paper to Wemos D1 mini
// BUSY → D2, RST → D4, DC → D3, CS → D8, CLK → D5, DIN → D7, GND → GND, 3.3V → 3.3V

I also uncommenting the corresponding line in sketch
#include <GxGDEW075Z09/GxGDEW075Z09.cpp> // 7.5" b/w/r

I do not anything else modified inside the sketch

By uploading the sketch with connected D1 - HAT - Display, the compiling running without error but at the end no connection to the serial port will be established - resulting in timeout, see error below

esptool.py v2.6
esptool.py v2.6
Serial port COM3
Traceback (most recent call last):

Checking the com ports, no error, they are working with different sketches.
Without connection to HAT and Display, the sketch is working and I do get information on the serial monitor. checking wiring and so on …

I do not have any idea, also didn’t find a hint somewhere else.
Would be great if there is any idea or hint for solution.

Hi athoma,

Try to use a different pin for CS, for hardware connection and as constructor parameter.

The CS pin of some e-papers interferes with boot mode selection on D8.

Good Luck!

Great hint, thanks this goes is the right direction ...
first I disconnect cable CS
Upload ist working, afterward I connect CS and sketch and display are working

Where to find a suggestion how to use CS on other Pins.

In any case thank You so much....
Yours Armin

You could use any pin that is not already used, and isn’t involved with boot mode itself.

D4 has been used successfully, see e.g. https://github.com/ZinggJM/GxEPD2/issues/13

You could also try with an added pull-down resistor on D8, e.g 3.3k, the internal one is too weak.


Solved ...
Thanks again with Your hints and links this (my) problem is solved.
Great Job