/*
  Forum: https://forum.arduino.cc/t/falling-interrupt-triggers-many-times-per-event/1356817/4
  Wokwi: https://wokwi.com/projects/423601736139637761

  Original: bmoerdyk2
  Modified: DaveX  -> Implemented Limited     StromZaehler()
  Modified: ec2021 -> Re-Implemented Original StromZaehler()

*/

//#define LIMITED

#define pinInputZaehler     27  //verified, has internal pull-up
volatile uint32_t zaehler = 0;  //volatile - can be changed in the interrupt
volatile unsigned long zaehlerMillis = 0; //volatile - can be changed in the interrupt
uint32_t zaehlerLast = 0;  //only changed in function
unsigned zaehlerMillisLast = 0;  //only changed in function
double zaehlerPower_W;
char a2dstr[128];

void setup() {
  //in void setup():
  Serial.begin(115200);
#ifdef LIMITED
  Serial.println("Limited");
#else
  Serial.println("Original");
#endif
  pinMode(pinInputZaehler, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(pinInputZaehler), StromZaehler, FALLING);
}
void loop() {
  // in void loop():
  ZaehlerStatus();

}

#ifdef LIMITED
// interrupt function Limited:
void StromZaehler() {
  uint32_t now = millis();
  static uint32_t lastInt = 0;
  if (now - lastInt < 10) return;
  lastInt = now;
  zaehler = zaehler + 1;
  zaehlerMillis = now;
}
#else
// interrupt function Original:
void StromZaehler() {
  zaehler = zaehler + 1;
  zaehlerMillis = millis();
}
#endif

//calculation function
void ZaehlerStatus() {
  if (zaehler != zaehlerLast) {    // pulse = 0.5kWh.  1p/h = 0.5kW
    if (zaehlerMillisLast != 0) {  //avoid calculation when there haven't been two good pulses.
      zaehlerPower_W = 3600.0 * 0.5 * float(zaehler - zaehlerLast) / float((zaehlerMillis - zaehlerMillisLast) / 1000.0);
      sprintf(a2dstr, "Z:%i/%i T:%i/%i", zaehler, zaehlerLast, zaehlerMillis, zaehlerMillisLast);
      Serial.println(a2dstr);
    }
    zaehlerMillisLast = zaehlerMillis;
    zaehlerLast = zaehler;
  }
}