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Running on my Adafruit Feather M0, my loop() was always blocking on readData(). I believe the problem is that touched() was returning 'true' even when no touch was detected (and thus no data for readData()).

If I am reading the datasheet correctly, I believe a "touch detected" is signalled by bit15 being set in CRF0. The current touched() code returns true whenever CRF0 is non-zero, which happens frequently even when no touch was detected.

I believe touched() should be something like:

 return readRegister16(_REG_CFR0) & (CFR0_PENMODE | CFR0_STATUS) >>15;

I was able to workaround the problem in my test code, by adding a TOUCHED_DETECTED macro that tests bit15 only

 #define _REG_CFR0       (0xC << 3)
 #define CFR0_STATUS             (1 << 14)
 #define CFR0_PENMODE            (1 << 15)
 #define TOUCH_DETECTED(t)   (bool) (((t).readRegister16(_REG_CFR0) & (CFR0_PENMODE | CFR0_STATUS) ) >> 15)

Lines 138 & 139 in TSC2004.cpp should read:

*z = *x * (z2/z1 - 1);                             // per page 15 of the datasheet
*z = *z * _RESISTOR_VAL / 4096;

Yeah, I know that *z *= should work but the compiler optimizes out the first line if the 2nd line isn't changed, and you still get only zero.

Make these 2 changes and it returns non-zero values. Note that it returns lower values for lighter touches, contrary to what I expected, but this is reasonable since resistance will decrease with higher pressure.

This version includes my touched() fix, referenced in the other issue, as well.

TSC2004.zip