Max Gramser
22 lines
1.2 KiB
Markdown
22 lines
1.2 KiB
Markdown
# XPT2046 input stabilization
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Based on ESPHome 2026.6.2's `esphome/components/xpt2046` (license alongside).
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The sample handoff in `touchscreen/xpt2046.cpp` and filter/calibration members
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in `touchscreen/xpt2046.h` differ from upstream. `touch_filter.h` is local.
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The installed CYD produced widely separated coordinates at first contact.
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The filter requires three samples within 100 ADC units before reporting a
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new contact, ignores isolated large jumps, and requires two absent-pressure
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samples before reporting release. Normal continuous drags use a small
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moving average; large movements are accepted after three stable samples.
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Use polling (20 ms in the device configuration), not an IRQ-only setup: the
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filter needs follow-up samples while confirming a contact or release.
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Run `tests/test_touch_filter.cpp` when changing the filter or updating ESPHome.
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An optional affine raw-coordinate correction defaults to the identity.
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The device profile sets its six coefficients at boot, fitted to median
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filtered corner readings from this particular panel. Raw diagnostic getters
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still expose the original filtered ADC values, allowing recalibration without
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mistaking corrected coordinates for physical measurements.
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