Interrupt help

Using Arduino Project Guidance
12

If you want to time your interrupt counts do not use delay. Use the "blink without delay" millis() timer approach. Only disable interrupts briefly to read data. Software Serial requires interrupts to be enabled. I would suggest that you read Nick Gammon's tutorial on interrupts Gammon Forum : Electronics : Microprocessors : Interrupts

Here's an example of timing an interrupt count

volatile unsigned long  count = 0;
unsigned long copyCount = 0;

unsigned long lastRead = 0;
unsigned long interval = 1000;//one second

void setup()
{
  Serial.begin(115200);
  Serial.println("start...");
  
  pinMode(2,INPUT_PULLUP);
  attachInterrupt(0, isrCount, RISING); //interrupt signal to pin 2
}

void loop()
{
  if (millis() - lastRead >= interval) //read interrupt count every second
  {
    lastRead  += interval;
    // disable interrupts,make copy of count,reenable interrupts
    noInterrupts();
    copyCount = count;
    count = 0;
    interrupts();
 
    Serial.println(copyCount);

  }
}

void isrCount()
{
  count++;
}