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pelgraine
128 lines
4.0 KiB
C++
128 lines
4.0 KiB
C++
#pragma once
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// =============================================================================
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// TouchInput - Minimal CST328/CST3530 touch driver for T-Deck Pro
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//
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// Uses raw I2C reads on the shared Wire bus. No external library needed.
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// Protocol confirmed via raw serial capture from actual hardware:
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//
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// Register 0xD000, 7 bytes:
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// buf[0]: event flags (0xAB = idle/no touch, other = active touch)
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// buf[1]: X coordinate high data
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// buf[2]: Y coordinate high data
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// buf[3]: X low nibble (bits 7:4) | Y low nibble (bits 3:0)
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// buf[4]: pressure
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// buf[5]: touch count (& 0x7F), typically 0x01 for single touch
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// buf[6]: 0xAB always (check byte, ignore)
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//
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// Coordinate formula:
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// x = (buf[1] << 4) | ((buf[3] >> 4) & 0x0F) → 0..239
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// y = (buf[2] << 4) | (buf[3] & 0x0F) → 0..319
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//
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// Hardware: CST328 at 0x1A, INT=GPIO12, RST=GPIO38 (V1.1)
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//
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// Guard: HAS_TOUCHSCREEN
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// =============================================================================
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#ifdef HAS_TOUCHSCREEN
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#ifndef TOUCH_INPUT_H
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#define TOUCH_INPUT_H
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#include <Arduino.h>
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#include <Wire.h>
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class TouchInput {
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public:
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static const uint8_t TOUCH_ADDR = 0x1A;
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TouchInput(TwoWire* wire = &Wire)
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: _wire(wire), _intPin(-1), _initialized(false), _debugCount(0), _lastPoll(0) {}
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bool begin(int intPin) {
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_intPin = intPin;
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pinMode(_intPin, INPUT);
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// Verify the touch controller is present on the bus
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_wire->beginTransmission(TOUCH_ADDR);
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uint8_t err = _wire->endTransmission();
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if (err != 0) {
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Serial.printf("[Touch] CST328 not found at 0x%02X (err=%d)\n", TOUCH_ADDR, err);
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return false;
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}
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Serial.printf("[Touch] CST328 found at 0x%02X, INT=GPIO%d\n", TOUCH_ADDR, _intPin);
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_initialized = true;
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return true;
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}
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bool isReady() const { return _initialized; }
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// Poll for touch. Returns true if a finger is down, fills x and y.
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// Coordinates are in physical display space (0-239 X, 0-319 Y).
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// NOTE: CST328 INT pin is pulse-based, not level. We cannot rely on
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// digitalRead(INT) for touch state. Instead, always read and check buf[0].
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bool getPoint(int16_t &x, int16_t &y) {
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if (!_initialized) return false;
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// Rate limit: poll at most every 20ms (50 Hz) to avoid I2C bus congestion
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unsigned long now = millis();
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if (now - _lastPoll < 20) return false;
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_lastPoll = now;
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uint8_t buf[7];
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memset(buf, 0, sizeof(buf));
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// Write register address 0xD000
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_wire->beginTransmission(TOUCH_ADDR);
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_wire->write(0xD0);
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_wire->write(0x00);
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if (_wire->endTransmission(false) != 0) return false;
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// Read 7 bytes of touch data
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uint8_t received = _wire->requestFrom(TOUCH_ADDR, (uint8_t)7);
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if (received < 7) return false;
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for (int i = 0; i < 7; i++) buf[i] = _wire->read();
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// buf[0] == 0xAB means idle (no touch active)
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if (buf[0] == 0xAB) return false;
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// buf[0] == 0x00 can appear on finger-up transition — ignore
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if (buf[0] == 0x00) return false;
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// Touch count from buf[5]
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uint8_t count = buf[5] & 0x7F;
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if (count == 0 || count > 5) return false;
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// Parse coordinates (CST226/CST328 format confirmed by hardware capture)
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// x = (buf[1] << 4) | high nibble of buf[3]
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// y = (buf[2] << 4) | low nibble of buf[3]
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int16_t tx = ((int16_t)buf[1] << 4) | ((buf[3] >> 4) & 0x0F);
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int16_t ty = ((int16_t)buf[2] << 4) | (buf[3] & 0x0F);
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// Sanity check (panel is 240x320)
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if (tx < 0 || tx > 260 || ty < 0 || ty > 340) return false;
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// Debug: log first 20 touch events with parsed coordinates
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if (_debugCount < 50) {
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Serial.printf("[Touch] Raw: %02X %02X %02X %02X %02X %02X %02X → x=%d y=%d\n",
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buf[0], buf[1], buf[2], buf[3], buf[4], buf[5], buf[6],
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tx, ty);
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_debugCount++;
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}
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x = tx;
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y = ty;
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return true;
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}
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private:
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TwoWire* _wire;
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int _intPin;
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bool _initialized;
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int _debugCount;
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unsigned long _lastPoll;
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};
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#endif // TOUCH_INPUT_H
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#endif // HAS_TOUCHSCREEN
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