Touch Calibration

Touch Rotation

When you rotate the display, touch input also needs rotation. The GUI method handles this automatically, but command-line rotation requires manual touch calibration.

Calibration Matrices

Touch rotation uses a libinput calibration matrix. Each rotation angle has a specific matrix:

Rotation	Matrix Values
0° (default)	1 0 0 0 1 0
90° (left)	0 -1 1 1 0 0
180° (inverted)	-1 0 1 0 -1 1
270° (right)	0 1 0 -1 0 1

Applying Touch Rotation

Permanent (udev rule)

Create a udev rule file:

sudo nano /etc/udev/rules.d/99-waveshare-touch.rules

Add the appropriate line for your rotation:

# For 90° rotation
ENV{ID_INPUT_TOUCHSCREEN}=="1", ENV{LIBINPUT_CALIBRATION_MATRIX}="0 -1 1 1 0 0"

# For 180° rotation
# ENV{ID_INPUT_TOUCHSCREEN}=="1", ENV{LIBINPUT_CALIBRATION_MATRIX}="-1 0 1 0 -1 1"

# For 270° rotation
# ENV{ID_INPUT_TOUCHSCREEN}=="1", ENV{LIBINPUT_CALIBRATION_MATRIX}="0 1 0 -1 0 1"

Uncomment only the line matching your display rotation.

Reboot to apply:

sudo reboot

Temporary (xinput)

For testing, use xinput (requires X11):

# Find your touch device
xinput list

# Apply rotation (example for 90°)
xinput set-prop "Goodix Capacitive TouchScreen" \
  "libinput Calibration Matrix" 0 -1 1 1 0 0 0 0 1

Note

This is temporary and resets on reboot. Use the udev rule for permanent configuration.

Touch Modes

The display supports two touch modes in Raspberry Pi OS:

Mouse Emulation (Default)

• Single touch controls mouse cursor
• Tap = left click
• Long press = right click
• Double-tap supported
• Best for desktop use

Multitouch Mode

• Full 10-point multitouch
• Pinch-to-zoom, gestures
• No right-click or double-tap
• Best for touch-optimized applications

Switching Modes

1. Open Menu → Preferences → Control Center → Screens
2. Select Touchscreen tab
3. Choose Mouse Emulation or Multitouch
4. Click Apply

Verifying Touch

Check Touch Device

# List input devices
cat /proc/bus/input/devices | grep -A5 "Goodix"

You should see:

N: Name="Goodix Capacitive TouchScreen"

Test Touch Input

# Install evtest if needed
sudo apt install evtest

# Monitor touch events
sudo evtest /dev/input/event0

Touch the screen - you should see coordinate data.

Troubleshooting Touch

Issue	Solution
Touch doesn’t respond	Check power connection, verify GT9271 detected
Touch offset from display	Apply calibration matrix matching rotation
Touch inverted	Wrong matrix - try different rotation value
Multitouch not working	Enable Multitouch mode in Screen Configuration

See Touch Problems for more solutions.