// Fixed Touch Pad - Pull-up version (Ardra PCB)
// Touch pulls pin LOW → delta goes NEGATIVE when touched

#define TOUCH_PIN    PIN_PA4
#define NUM_SAMPLES  10
#define DELTA_THRESH 40       // Touch = delta drops BELOW negative of this
#define DRIFT_SPEED  0.02

float baseline = 0;

long measureOnce() {
  long count = 0;
  pinMode(TOUCH_PIN, OUTPUT);
  digitalWrite(TOUCH_PIN, LOW);
  delayMicroseconds(10);

  pinMode(TOUCH_PIN, INPUT);
  while (digitalRead(TOUCH_PIN) == LOW && count < 5000) count++;

  return count;
}

float measureAvg() {
  long total = 0;
  for (int i = 0; i < NUM_SAMPLES; i++) {
    total += measureOnce();
    delayMicroseconds(200);
  }
  return (float)total / NUM_SAMPLES;
}

void setup() {
  Serial.begin(115200);
  delay(500);

  // Calibration
  long cal = 0;
  for (int i = 0; i < 50; i++) {
    cal += measureOnce();
    delay(10);
  }
  baseline = (float)cal / 50.0;
}

void loop() {
  float reading = measureAvg();
  float delta = reading - baseline;

  // Serial Plotter friendly output (3 channels)
  Serial.print(reading);
  Serial.print(" ");
  Serial.print(baseline);
  Serial.print(" ");
  Serial.println(delta);

  // Touch detection
  if (delta < -DELTA_THRESH) {
    // Optional: you can toggle an LED or do something here
  } else {
    // Drift correction only when not touched
    baseline = baseline + (reading - baseline) * DRIFT_SPEED;
  }

  delay(50);
}