/*
 * SkyEar - STM32 dummy pressure sensor readout
 * Wokwi simulation: potentiometer stands in for the differential
 * pressure sensor. Prints to the built-in Serial Plotter.
 *
 * Note: deliberately does NOT call analogReadResolution() or
 * pinMode(..., INPUT_ANALOG) - Wokwi's STM32 ADC simulation is a
 * partial implementation and those calls can hang the sketch before
 * it ever reaches Serial output.
 *
 * A synthetic 0.5 Hz infrasound wave is generated in software and
 * combined with the potentiometer reading, so the plotted output
 * looks like a live microbarometer trace instead of a flat line.
 *
 * OUTLIER GUARD: Wokwi's STM32 serial/float-printing simulation has
 * known glitches that can corrupt an occasional sample into a huge
 * garbage number (seen: 83968072.000) even though our own math can
 * only ever produce a value in roughly +/-15 Pa. Rather than chase
 * the simulator's internal bug, we clamp the value actually sent to
 * Serial: anything outside a generous plausible range is replaced
 * with the last known-good value, so one bad sample can't wreck the
 * plotter's Y-axis scale.
 */
#include <math.h>

#define POT_PIN PA0
const float ADC_MAX = 1023.0;          // stm32duino default ADC resolution (10-bit)
const float PRESSURE_RANGE_PA = 50.0;  // simulated full-scale, +/- 50 Pa
const unsigned long SAMPLE_INTERVAL_MS = 10; // 100 Hz sampling
unsigned long lastSample = 0;

// Synthetic infrasound parameters
const float INFRASOUND_FREQ_HZ = 0.5;   // 0.5 Hz = one cycle every 2 seconds
const float INFRASOUND_AMPLITUDE_PA = 5.0;

// Outlier guard
const float MAX_PLAUSIBLE_PA = 30.0; // true max is ~15 Pa, this leaves margin
float lastGoodValue = 0;

void setup() {
  Serial.begin(115200);
  // No unlabeled prints here - keeps the plotter's Y-axis clean.
}

void loop() {
  unsigned long now = millis();
  if (now - lastSample >= SAMPLE_INTERVAL_MS) {
    lastSample = now;

    // Potentiometer -> sensor baseline reading
    int raw = analogRead(POT_PIN);
    raw = constrain(raw, 0, (int)ADC_MAX); // guard against ADC glitches
    float pressure_pa = ((raw / ADC_MAX) * 2.0 - 1.0) * PRESSURE_RANGE_PA;

    // Synthetic infrasound wave, injected in software
    float timeSeconds = now / 1000.0;
    float infrasound_pa =
        INFRASOUND_AMPLITUDE_PA * sin(2.0 * PI * INFRASOUND_FREQ_HZ * timeSeconds);

    // Combine: pot sets the slow baseline/offset, the sine wave is the
    // "detected" infrasonic signal riding on top of it
    float combined_pa = pressure_pa * 0.2 + infrasound_pa;

    // Reject implausible/corrupted samples before they ever reach Serial
    if (isnan(combined_pa) || isinf(combined_pa) || fabs(combined_pa) > MAX_PLAUSIBLE_PA) {
      combined_pa = lastGoodValue;
    } else {
      lastGoodValue = combined_pa;
    }

    Serial.print("Pressure_Pa:");
    Serial.println(combined_pa, 3);
  }
}