Calculating rpm using 1a57hr photointerrupter

Projects Programming
1

I am attempting to measure the rpm of a propeller using a photo interrupter and have the circuit and code working reasonably well. I am able to calculate how many times the rotor passes through the interrupter however I am having trouble finding the time it takes for it all to happen.

Might anyone have some suggestions on how to keep track of the elapsed time or a method of sectioning off 30 second chunks to analyze separately?

Here's the code I am using at the moment:

int val;
int rpm;
const byte InterruptPin = 2;
volatile byte rev;

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

pinMode(InterruptPin, INPUT_PULLUP);

attachInterrupt(digitalPinToInterrupt(InterruptPin), counter, RISING);
}

void loop() {

rpm = 60*rev/(millis()/1000);

val = analogRead(A0);

Serial.print("Value:");
Serial.print(val);

Serial.print("\t\t");
Serial.print("RPM:");
Serial.print(rpm);

Serial.print("\t\t");
Serial.print("Revolutions:");
Serial.println(rev);

delay(5);
}

void counter(){
rev++;
}

2

Might anyone have some suggestions on how to keep track of the elapsed time or a method of sectioning off 30 second chunks to analyze separately?

A perusal of the blink without delay example is in your future. Instead of blinking, you calculate rpm.

You probably want to reset rev at some point...