126 lines
4.0 KiB
Markdown
126 lines
4.0 KiB
Markdown
# Touchscreen issues
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If the screen is connected over USB, issues with the cable may cause similar symptoms. For that, please see [this guide](Physical_Install.md#cable-issues).
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## Touch not working on RaspberryOS and derivatives
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Some DSI screens have issues where touch doesn't work with the default configuration.
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The current workaround/temporary fix involves changing the kernel driver module used for these displays.
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Open `/boot/config.txt` for editing using `sudo nano /boot/config.txt` and change
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```sh
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dtoverlay=vc4-kms-v3d
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```
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to
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```sh
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dtoverlay=vc4-fkms-v3d
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```
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Close the nano editor using `ctrl`+`x` (exit), then `y` for yes (save).
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**Reboot** to apply changes.
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If that doesn't fix it, you can try commenting these lines out, resulting in:
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```sh
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# dtoverlay=vc4-kms-v3d
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# max_framebuffers=2
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```
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**Reboot** to apply changes.
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## Touch rotation and matrix
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If the touch works but registers touch input in a different location from the input, then you may need to apply an input transformation matrix.
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First you will need your device name. On a terminal, run:
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```sh
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DISPLAY=:0 xinput
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```
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Output:
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```text
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⎡ Virtual core pointer id=2 [master pointer (3)]
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⎜ ↳ Virtual core XTEST pointer id=4 [slave pointer (2)]
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⎜ ↳ ADS7846 Touchscreen id=6 [slave pointer (2)]
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⎣ Virtual core keyboard id=3 [master keyboard (2)]
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↳ Virtual core XTEST keyboard id=5 [slave keyboard (3)]
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```
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In this case the device is the ADS7846 Touchscreen, yours may be different
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You can test a change by running:
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```sh
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DISPLAY=:0 xinput set-prop "<device name>" 'Coordinate Transformation Matrix' <matrix>
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```
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Where the matrix can be one of the following options:
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| Rotation | Matrix |
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| ------------------------------------- | --------------------- |
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| 0° | `1 0 0 0 1 0 0 0 1` |
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| 90° Clockwise | `0 -1 1 1 0 0 0 0 1` |
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| 90° Counter-Clockwise | `0 1 0 -1 0 1 0 0 1` |
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| 180° (Inverts X and Y) | `-1 0 1 0 -1 1 0 0 1` |
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| invert Y | `-1 0 1 1 1 0 0 0 1` |
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| invert X | `-1 0 1 0 1 0 0 0 1` |
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| expand to twice the size horizontally | `0.5 0 0 0 1 0 0 0 1` |
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For more in-depth guidance on using Coordinate Transformation Matrices:
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* [Ubuntu wiki InputCoordinateTransformation](https://wiki.ubuntu.com/X/InputCoordinateTransformation)
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* [Libinput docs](https://wayland.freedesktop.org/libinput/doc/1.9.0/absolute_axes.html)
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It has been reported that the touch expands with screens that don't use HDMI. This is due to the composite output,
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which enables automatically as a fallback when no HDMI device is plugged in.
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If this is the case, adding `enable_tvout=0` to `/boot/config.txt` and reboot.
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!!! example
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```sh
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DISPLAY=:0 xinput set-prop "ADS7846 Touchscreen" 'Coordinate Transformation Matrix' -1 0 1 0 -1 1 0 0 1
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```
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To make this permanent, modify the file `/etc/udev/rules.d/51-touchscreen.rules`:
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```bash
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sudo nano /etc/udev/rules.d/51-touchscreen.rules
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```
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and add following line
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```sh
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ACTION=="add", ATTRS{name}=="<device name>", ENV{LIBINPUT_CALIBRATION_MATRIX}="<matrix>"
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```
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Close the nano editor using `ctrl`+`x` (exit), then `y` for yes (save).
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---
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As an alternative **if the above doesn't work**:
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edit `/usr/share/X11/xorg.conf.d/40-libinput.conf`
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```bash
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sudo nano /usr/share/X11/xorg.conf.d/40-libinput.conf
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```
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With the following contents:
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```sh
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Section "InputClass"
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Identifier "libinput touchscreen catchall"
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MatchIsTouchscreen "on"
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MatchDevicePath "/dev/input/event*"
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Driver "libinput"
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Option "TransformationMatrix" "0 -1 1 1 0 0 0 0 1"
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EndSection
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```
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Close the nano editor using `ctrl`+`x` (exit), then `y` for yes (save).
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