PiScreen2 calibration challenge

[Philippe Jeanmaire]

Hi Mark,

I develop my applications on Raspberry Pi3A+ with PiScreen2.  Did an initial calibration and recorded the results in 99-calibration.conf.

All worked well, and after 2 months I am ready to get prototypes in the field.... But I observed over time that the taps on the left side of the screen got less and less precise... to the point where I cannot tap on buttons in top left corner.

I use 'ts_calibrate' to read coordinates of set points.
screen 1 results (point: X, Y):

top left:                571, 1313
top right:          3483,  949
bottom right:  3487, 3074
bottom left:       566, 2705

The Y range on the left side is 1313 - 2705  and on the right side 949 - 3074!  Running 'ts_test' I cannot drag the cursor to the bottom or the top on the left side.

Same test on a new PiScreen2 the results are (screen 2):

top left:                528,  794
top right:          3487,   771
bottom right:  3493, 3314
bottom left:       523, 3331

and cursor can be dragged over the whole screen... which seems 'normal'

What are your thoughts on these observations?

Note: I have replaced the tall 2x13 female header (situated on the opposite side of the top left corner of the screen) with a low profile header .  Could the heat used to solder it have something to do with it?

Phil

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