topic Re: Inaccurate touchscreen coordinates in i.MX Processors

Inaccurate touchscreen coordinates

Jamier — Mon, 28 Aug 2023 18:38:15 GMT

I've got a system built with Yocto Kirkstone using a 720x1280 display with a focaltouch capacitive display. The display is driven using the weston-imx layer. The display is portrait native, and we are rotating it 90deg in the weston.ini file

I find the touching near the edges gives inaccurate coordinates. I took some measurements of position and found that the touch points on x axis are linearly displaced as if there is a calibration error. (slope 0.7, offset -103)

I am certain the device try defines the focaltech display coordinates correctly:

focaltech,display-coords = <0 0 720 1280>;

I wanted to see if the weston-touch-calibrator could be used to fix this, but it appears it is not included in my build, and it isn't obvious how to include it.

Does anyone have some tips on how to either investigate/fix the inaccuracy or include weston-touch-calibrator in the build?

I've attached dmesg in case that helps.

Thanks.

Re: Inaccurate touchscreen coordinates

Rita_Wang — Tue, 29 Aug 2023 03:12:07 GMT

Which board and which version BSP are you using?

Re: Inaccurate touchscreen coordinates

Jamier — Tue, 29 Aug 2023 17:16:03 GMT

We are using a custom board based on imx8mm and a custom BSP based on Yocto Kirkstone.

Re: Inaccurate touchscreen coordinates

Rita_Wang — Tue, 05 Sep 2023 06:20:41 GMT

When your system boot up, you can go to the /dev/input directory to see if there is event exist , to see if the touch screen have the interrupt or not.

Re: Inaccurate touchscreen coordinates

Jamier — Mon, 11 Sep 2023 16:22:02 GMT

In working with the touch panel manufacturer, Leadtek it appears to be a firmware problem with the touch controller. They've made a change that appears to help the accuracy when in non-native landscape mode. Still testing but so far it's helped.

Re: Inaccurate touchscreen coordinates

Jamier — Mon, 11 Sep 2023 16:23:01 GMT

In working with the touch panel manufacturer, Leadtek, it appears to be a firmware problem with the touch controller. They've made a change that helps the accuracy when in non-native landscape mode. Still testing but so far it's helped.