XPT2046 improvement discussion

[liebman]

I've been having an issue with this input driver with spurious input events. This is where the IRQ line goes low for ~ 8us, measured with a scope. Looking at other implementations I see that some compute the Z (or press pressure). Maybe this should only return a new input based on some Z threshold.

Now the datasheet is very confusing on this subject and gives formula that require knowing the X and or Y resistance values. (currently I'm playing with what this library does.)

Any thoughts?

[liebman]

I've created a PR that works (at least for me).....

[C47D]

Hi @liebman, I have also had problems with that touch sensor, for any reason the IRQ doesn't go low on my screen, so I also tried to implement the touch detection based on the Z coordinate. See here, but my pc was really slow, it took me about 10 mins to build the project so I didn't went any further.

I will check your PR, hopefully we can all improve this code base.

[liebman]

Hmm - this patch still requires the IRQ. My issue was lots of spurious IRQ with no touch. Should be simple enough to have the IRQ pin be optional, I may have time to try that this weekend. Downside will be more traffic on SPI, in my case I'm sharing SPI with the display so I like the IRQ at least telling me I don't need to read the touch panel.

[liebman]

@C47D it was easier than I expected. If you enable the Check touch pressure to validate LV_TOUCH_PIN_IRQ option for xp2046 then there is an additional option Only use touch pressure and not IRQ to detect a touch that will ignore IRQ (the pin will not even be configured) and only use pressure to determine a touch. Let me know how this works for you.