Esp32 ePaper contrast issue

ESPHome
1

Hello,
I have juste created my 1st epaper display with an ESP32. It is working fine except one thing.
At start the contrast is perfect and progressively contrast is decreasing at each refresh. If I disconnect the esp32 drom power, wait a few time and replug it is restarting with good contrast.

Do you know what can be the problem ? And how can I solve it ?

Thanks

2

Try with full_update_every: 1

3

The dislpay model I have to use (7.50in-bv3) can not authorize full_update_every: 1.
I tried the model 7.50inv2p but then I have no display at all.

4

For testing (maybe partial update is not even your problem), try something like this:

    lambda: |-
      it.fill(COLOR_OFF);
      it.print(10, 10, id(my_font), "Testing");
5

If partial refresh is not your problem, it could be that the display is not powering down between refreshes. Some models require the busy pin to be inverted, some not.

It could also be related to the voltage settings. Waveshare boards have switches to set the right voltage.

6

ll test that.

7

The display is not reset completely before it is being updated.
ePaper displays need to be reset by flashing the display a couple of times between white and black.
This flashing makes increase the update time, so many coders try to lower the time by skipping a few flashes or do it faster, but that will slowly dull the screen contrast.