ESP32 433MHz receiver

main.cpp

#include <Arduino.h>

#define RF_DATA_PIN 32

#define TIMING_SYNC_SHORT_HIGH 190
#define TIMING_SYNC_SHORT_LOW 300

#define TIMING_SYNC_LONG_HIGH 1580
#define TIMING_SYNC_LONG_LOW 1520

#define TIMING_DATA_HIGH 210
#define TIMING_DATA_LOW_1 920
#define TIMING_DATA_LOW_0 560

#define TIMING_NOISE_LONG 2000
#define TIMING_NOISE_SHORT 140

#define TIMING_TOLERANCE 120

#define PACKET_LENGTH 40

unsigned long previousTime = 0;
int duration = 0;

int countShortSyncs = 0;
int countLongSyncs = 0;

bool timeWithinTolerance(int baseline, int measurement)
{
  return measurement >= baseline - TIMING_TOLERANCE && measurement <= baseline + TIMING_TOLERANCE;
}

void resetCounters() {
  countShortSyncs = 0;
  countLongSyncs = 0;
}

void ICACHE_RAM_ATTR handleInterrupt()
{
  unsigned long time = micros();

  duration = time - previousTime;
  previousTime = time;

  if (duration > TIMING_NOISE_LONG || duration < TIMING_NOISE_SHORT)
  {
    return;
  }

  if (countShortSyncs < 4 && timeWithinTolerance(TIMING_SYNC_SHORT_LOW, duration)) {
    Serial.print("Short sync: ");
    Serial.println(countShortSyncs + 1);
    countShortSyncs++;
    return;
  }

  if (countShortSyncs != 4) {
    resetCounters();
    return;
  }

  if (timeWithinTolerance(TIMING_SYNC_LONG_LOW, duration)) {
    Serial.print("Long sync: ");
    Serial.println(countLongSyncs + 1);
    countLongSyncs++;
    return;
  }

  if (countLongSyncs != 4) {
    resetCounters();
    return;
  }

}

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

  pinMode(digitalPinToInterrupt(RF_DATA_PIN), INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(RF_DATA_PIN), handleInterrupt, RISING);
}

void loop()
{
}