XPT2046 optionally (Kconfig option) validate a touch with pressure, not just IRQ low

[liebman]

Sometimes IRQ is very noisy an prevents things like idle time detection. This PR will check to insure there is pressure detected on the panel, not just the noisy IRQ signal. Disabled by default in Kconfig.
Fixes #7

[liebman]

I've added an additional config option to use pressure only and ignore IRQ (not even configure the pin).

[C47D]

Hi @liebman, all looks good. Do you think is it possible to move the touch detection code into a new function that returns 0 when there's no touch detected and another positive number when there's touch detected? Something like xpt2048_is_press_detected?

[liebman]

@C47D is there a specific use case for this? (your asking for this to be non-static I assume)

EDIT: or maybe this is just to make the logic more readable.... Can it return a bool?

[C47D]

EDIT: or maybe this is just to make the logic more readable.... Can it return a bool?

Yes, to make the logic more readable, and yes, it can return a bool or an enum, I find enums be more readables.

typedef enum {
TOUCH_NOT_DETECTED = 0,
TOUCH_DETECTED = 1,
} xpt2046_touch_detected;

[liebman]

@C47D I'm looking for a better name for the Z_MIN constant. Any ideas? (as usual it's naming that's the hardest) Maybe move to the header and name XPT2046_Z_MIN?)

[C47D]

Maybe Z_TOUCH_DETECTION_THRESHOLD?, here I was exposing the z threshold in the menuconfig, and added a function so the user can change the threshold at runtime, but maybe that's an overkill.

[liebman]

@C47D I've refactored it a bit. One more change that may help is to make the Kconfig part more of a choose one of three.

• IRQ only (default for backwards compatibility)
• IRQ & Touch
• Touch only

Thoughts?

[liebman]

Tried the Kconfig choice, let me know what you think.

[C47D]

Hi, it looks good, I don't have any hardware to test it, is it ready to merge?

[liebman]

Yes :-)

[C47D]

Thanks for the work you've put into this. I will try to test this with hardware once I get some free time.