/*
Voltaat learn (http://learn.voltaat.com)
Link for full tutorial: put the link of the tutorial here

Tutorial: measure the speed of any motor with arduino!

The function of this sketch is to obtain the motor speed values and display it on your computer.


Connections from the IR speed sensor to arduino :

• VCC  → Arduino 5V pin

• GND →  Arduino GND pin

• D0 →  Arduino pin 2


Connections from the motor  to 18650 battery holder:

• Motor  first wire  →  18650 battery holder negative wire

• Motor  second wire → 18650 battery holder positive wire


*/

int encoder = 2;

volatile unsigned int counter;
int rpm;


void setup() {
 //making interrupt every time there is a high pulse coming from the speed sensor
 attachInterrupt(0,countpulse,RISING);
  Serial.begin(9600);
}

void countpulse(){
//Each time it receives a high pulse, the counter increases by 1
       counter++;
}

void loop() {
 static uint32_t previousMillis;
 /*When a time of 1 second has passed, he calculates the number of revolutions during
 that second by dividing the counter value by 20 (which is the value of the number of
 slots in the encoder wheel) and then multiplying it by sixty in order to calculate
 the number of revolutions per minute */
 
 if (millis() - previousMillis >= 1000) {
           rpm = (counter/20)*60;          
           counter = 0;
           previousMillis += 1000;
 }
//It prints the speed on the screen in rpm values

 Serial.print("Speed: ");
 Serial.print(rpm);
 Serial.println(" rps");
 delay(100);
}