#393 Implement kickback voltage readings

[martinberlin]

Please check Issue #393 for details
Additionally update the SSL certificate for www-image (Loremflickr.com) usually this are renewed every year and this will make the jpeg download example SSL handshake fail.

Maybe Valentin what we can do is a bash or python script that just runs:

openssl s_client -showcerts -connect www.loremflickr.com:443 </dev/null

And fetches last certificate in the chain to store it in https://github.com/vroland/epdiy/tree/main/examples/www-image/ssl_cert

[vroland]

The kickback reading feature looks nice! I think the values we're getting are not quite the once we would expect from the labels, because the timing of the measurement is not the best. Ideally we would drive the waveform without pause until the measurement is complete, while currently we pause to do all the highlevel stuff. But that requires a lot more work and like this it can already be used for detecting broken displays and such, so I think we should bring it in :)

Before merging I'd prefer that the duplicate code (see comment) is refactored. Also I'd split out the www-image changes and the kickback voltage changes into separate PRs. On that note: Is there a specific reason for adding the whole jpegdec component now, when the only other change is the cert?

[martinberlin]

The kickback reading feature looks nice! I think the values we're getting are not quite the once we would expect from the labels, because the timing of the measurement is not the best. Ideally we would drive the waveform without pause until the measurement is complete, while currently we pause to do all the highlevel stuff. But that requires a lot more work and like this it can already be used for detecting broken displays and such, so I think we should bring it in :)

agree!

Before merging I'd prefer that the duplicate code (see comment) is refactored. Also I'd split out the www-image changes and the kickback voltage changes into separate PRs. On that note: Is there a specific reason for adding the whole jpegdec component now, when the only other change is the cert?

Jpegdec falled behind since the author also added faster decode using assembly.
But maybe we could just take latest version from https://components.espressif.com/components/bitbank2/jpegdec/versions/1.6.2 ?
Otherwise I fully agree next time let’s keep the PRs only specific to one single topic…

[martinberlin]

I will check over the weekend to see if I can get a better VCOM reading. But about the duplicate function please read my comment: It really does not make sense to refactor all just because a duplicate function that hardly someone will use. It involves adding more files and changing the structure. Something it makes sense if we do a bigger refactoring but not because of this VCOM voltage reading.
Also having to extrapolate this to a common v6/v7 boards forces to have many things defined there like config_reg, IO expander, TPS65185 etc. If we do that let's do it for a greater goal or refactor it when v8 comes. Then we do it to really reduce code and not for a single duplicate function.

[vroland]

Sure, I thought it would be a quick change to factor out that function, but if not it's fine. Only if we get more V7 variants we should think about refactoring that.

[vroland]

About JPEGDEC: For me it works if I delete the 'components' directory entirely and just run idf.py add-dependency "bitbank2/jpegdec^1.6.2". Then it creates a main/idf_component.yaml which makes the build system automatically download the component when I build. I think that's the most elegant solution :)

[martinberlin]

just run idf.py add-dependency "bitbank2/jpegdec^1.6.2"

Yes! Deleted what is components and add only added idf_component.yaml
So now it has less duplicated code. Only downside of doing this is that if you build on Arduino then you need to first install JPEGDEC as a library. But that is ok since is the Arduino IDE way to do stuff.
OK all green and it passes. Next PR will be to add the new v7 board without IO expander, that I've called "v7 raw" (Because it sounds a bit weird to call it "naked v7")