Add screen diagnostics example app

[jdoubleu]

This example app implements a simple interactive shell that lets you tinker with the display. You can draw simple shapes (i.e. everything the epd driver provides), read system information, etc. I've ported some of my screen test algorithms (i.e. render_stairs and render_grid) as well.

This can be helpful when debugging incompatible or broken displays or just experimenting with the draw functions.

Also note: the power_on command basically obsoletes the calibration_helper example.

[vroland]

Thank you, that looks useful! I'll test it a bit and hopefully merge it soon :)

[vroland]

Wow, that's awesome, I really like the interactive console!
I just noticed one minor thing: When I try to get the temperature without enabling power, the I2S read fails and the ESP runs into an assert and reboots. However, for some reason, it then goes into a boot loop trying to do the read again when it reboots, even after power cycling. Do you know why that is? I could only break the loop by adding a check to the temperature reading function, which I should probably do anyway...

[jdoubleu]

When I try to get the temperature without enabling power, the I2S read fails and the ESP runs into an assert and reboots. [...]

Hm, that's interesting. How do you know, it tries to read the temperature again? No, I have no clue why this happens.

[...] by adding a check to the temperature reading function [...]

That's probably a good idea! Gonna add this check.

[martinberlin]

Dear @jdoubleu what is the status of this I would also like to test it.

[jdoubleu]

Sorry for the long delay.

I just noticed one minor thing: When I try to get the temperature without enabling power, the I2S read fails and the ESP runs into an assert and reboots.

I am unable to reproduce this issue. With my v5 board, reading the temperature, even if the board isn't manually epd_poweron()'d seems to work fine.

Nonetheless I've added a fix which always turns on and off the epd before reading the temp.

[martinberlin]

This weekend I will start testing this that I think is a great contribution. @jdoubleu could you please merge back master that is now updated into your pull request?
I think won’t be much effort to update this since only initialization of epdiy changed and it’s not anymore per menuconfig.
So just a few lines need to be updated.

[vroland]

Hey @jdoubleu , I created a branch where your changes are rebased on epdiy 2.0.0. If you care that we merge your branch, could you rebase on main and cherry-pick dfeee32?
I can also just merge that branch, if you don't care about having specifically the branch from your fork merged.

[vroland]

Nvm, I can actually just merge this and then apply the fix :D Thanks again for the nice contribution, very useful!