void setup() {
  Serial.begin(115200);
  analogReadResolution(12); // Set ADC to 12-bit resolution (0-4095)
}

void loop() {
  int rawADC = analogRead(36); // Read from GPIO 36 (ADC1_CH0)
  float V_adc = 3.3 * rawADC / 4095.0; // Convert to voltage (0-3.3V)
  float V_sensor;

  // Piecewise linear transfer function
  if (V_adc <= 0.5) {
    V_sensor = 20 * V_adc; // Low-range
  } 
  else if (V_adc <= 2.5) {
    V_sensor = 2 * V_adc + 9; // Mid-range
  } 
  else {
    V_sensor = 5.6 * V_adc + 7.75; // High-range
  }

  // Print results
  Serial.printf("V_adc: %.2fV  →  V_sensor: %.2fV\n", V_adc, V_sensor);
  delay(500); 
}