geiger_counter_diy.ino

/**
 * 
 * Pin D2 -> Arduino Interruption
 * Pin D7 -> Buzzer
 * Pin D8 -> Led
 * Pin D9 -> External Interruption to connect other Arduino/Raspberry
 * 
 */

#define LOG_PERIOD 20000 //Logging period in milliseconds
#define MINUTE_PERIOD 60000

volatile unsigned long counts = 0; // Tube events
unsigned long cpm = 0; // CPM
unsigned long previousMillis; // Time measurement

const int inputPin = 2;
const int buzzerPin = 7;
const int ledPin = 8;
const int interruptionPin = 9;

void ISR_impulse() { // Captures count of events from Geiger counter board
  
  counts++;
  
  digitalWrite(buzzerPin, HIGH);
  digitalWrite(ledPin, HIGH);
  digitalWrite(interruptionPin, HIGH);
  
  Serial.println("click");
}

void setup() {
  
  Serial.begin(9600);

  pinMode(buzzerPin, OUTPUT);
  pinMode(ledPin, OUTPUT);
  pinMode(interruptionPin, OUTPUT);
  
  pinMode(inputPin, INPUT_PULLUP);  
  
  delayMicroseconds(50);
  
  EIFR |= (1 << INTF1); // Enable interrupts on Arduino Nano
  
  attachInterrupt(digitalPinToInterrupt(inputPin), ISR_impulse, RISING);

  digitalWrite(buzzerPin, LOW);
  digitalWrite(ledPin, LOW);
  digitalWrite(interruptionPin, LOW);
}

void loop() {

  digitalWrite(buzzerPin, LOW);
  digitalWrite(ledPin, LOW);
  digitalWrite(interruptionPin, LOW);
  
  unsigned long currentMillis = millis();

  if (currentMillis - previousMillis > LOG_PERIOD) {
    
    previousMillis = currentMillis;
    cpm = counts * MINUTE_PERIOD / LOG_PERIOD;

    Serial.println(String(cpm) + " cpm");
    counts = 0;
  }
}