Calibration of resistive touchscreens: Difference between revisions
Pzimmermann (talk | contribs) Create page for calibration of touchscreen, it is meant to be included in other pages |
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At our yocto images, we usually use libinput as library for handling input. | At our yocto images, we usually use libinput as library for handling input. | ||
==== Prerequisites ==== | ===== Prerequisites ===== | ||
* Yocto packages ''weston'', ''weston-init'' and ''weston-examples'' have to be installed inside the image. | * Yocto packages ''weston'', ''weston-init'' and ''weston-examples'' have to be installed inside the image. | ||
* The config file <tt>/etc/xdg/weston/weston.ini</tt> needs the following lines (to enable touchscreen calibration): | * The config file <tt>/etc/xdg/weston/weston.ini</tt> needs the following lines (to enable touchscreen calibration): | ||
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==== Steps for calibration ==== | ===== Steps for calibration ===== | ||
'''1.''' Get the touchscreen device name with weston-touch-calibrator | '''1.''' Get the touchscreen device name with weston-touch-calibrator | ||
Revision as of 07:38, 20 October 2023
On devices with resistive touchscreens, the touchscreen has to be calibrated.
At our yocto images, we usually use libinput as library for handling input.
Prerequisites
- Yocto packages weston, weston-init and weston-examples have to be installed inside the image.
- The config file /etc/xdg/weston/weston.ini needs the following lines (to enable touchscreen calibration):
[libinput] touchscreen_calibrator=true
After changing the configuration of weston, weston needs to be restarted:
| systemctl restart weston |
Steps for calibration
1. Get the touchscreen device name with weston-touch-calibrator
| XDG_RUNTIME_DIR=/var/run/user/$(id -u weston) weston-touch-calibrator |
Example result (bold part is needed for next steps):
| device "/sys/devices/platform/soc/2100000.bus/21a8000.i2c/i2c-2/2-0049/input/input0/event0" - head "DPI-1" |
2. Run weston-touch-calibrator on the device for starting the calibration. With the example part of the last result, the command looks like this (bold part is from the last result):
| XDG_RUNTIME_DIR=/var/run/user/$(id -u weston) weston-touch-calibrator -v /sys/devices/platform/soc/2100000.bus/21a8000.i2c/i2c-2/2-0049/input/input0/event0 |
Now you press the highlighted points at the touchscreen to calibrate it. You will now get an output on the console like this (the important part is marked bold):
| Calibration values: -0.001472 -1.081086 1.033880 -1.135099 0.000319 1.082698 |
3. To make the calibration permanent, you need to add a udev rule. Create the file /etc/udev/rules.d/touchscreen-cal.rules and use the calibration values there. With the result of the previous example, the file looks like this (bold part is the result of the last example):
SUBSYSTEM=="input", KERNEL=="event[0-9]*", ENV{ID_INPUT_TOUCHSCREEN}=="1", ENV{LIBINPUT_CALIBRATION_MATRIX}="-0.001472 -1.081086 1.033880 -1.135099 0.000319 1.082698"
