Request for information: STPME811_Min_Pressure

We are using IMX6s with 7" resistive touch displays.

I am attempting to add a feature so the user can adjust the touch screen sensitivity. I found this article:

Resistive Touch Screen on WinCE | Toradex Developer Center

The only sensitivity related setting that I see is “minimum pressure.”

;Minimum pressure 
;If the pressure is below this level, the X/Y measurement will be discarded. If STMPE811_Min_Pressure=0 then all touches cause a X/Y measurement.
"STMPE811_Min_Pressure"=20  ;default value

The lower the value the more sensitive, correct?

That would make sense to me, but during my testing, it seems the greater the value the more sensitive. Here are my test results:

10 = touch screen is not responsive at all
15 = touch screen is responsive to finger but not stylus
20 = touch screen is responsive to finger but not stylus
40 = touch screen is responsive to both finger and stylus

If the lower the value the more sensitive, then can anyone please explain why the touch screen only works with a stylus when set to 40 and higher. That seems backwards to me. I want to confirm that my test results match the expected results.

  • Colibri IMX6 DL 512MB V1.1B
  • Custom carrier board
  • Resistive touch screen (Shenzhen Huayuan VISLCD-070HYQPB40B23G-21TV and Kingtech PV07002LZR40B)
  • Windows CE 7 1.8 (vanilla Toradex image)

Hi @enafziger.procat
Yes, the expected behavior for the STMPE811_Min_Pressure is the lower the value, the more sensitive it becomes . Unfortunately, there is a bug in the STMPE driver related to incorrect settings for the accuracy of the pressure measurement, which leads to the behavior you observed. However, the maximum sensitivity can be achieved by setting the STMPE811_Min_Pressure to 0

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