#include
LiquidCrystal lcd(A5,A4,A3,A2,A1,A0);
#include
const int stepsPerRevolution = 200; // change this to fit the number of steps per revolution
Stepper myStepper(stepsPerRevolution, 8, 9, 10, 11);
volatile byte REV;
unsigned long int rpm,RPM;
unsigned long st=0;
unsigned long time;
int ledPin = 13;
int led = 0,RPMlen , prevRPM;
int flag = 0;

int flag1=1;
#define bladesInFan 2
float radius=4.7; // inch
int preSteps=0;
float stepAngle= 360.0/(float)stepsPerRevolution;
float minSpeed=0;
float maxSpeed=280.0;
float minSteps=0;
float maxSteps=maxSpeed/stepAngle;

void setup()
{
myStepper.setSpeed(60);
Serial.begin(9600);
pinMode(ledPin, OUTPUT);
lcd.begin(16,2);
lcd.print("Speedometer");
delay(2000);
attachInterrupt(0, RPMCount, RISING);
}

void loop()
{
readRPM();
radius=((radius * 2.54)/100.0); // convering in meter
int Speed= ((float)RPM * 60.0 * (2.0 * 3.14 * radius)/1000.0);
// RPM in 60 minute, diameter of tyre (2pi r) r is radius, 1000 to convert in km
int Steps=map(Speed, minSpeed,maxSpeed,minSteps,maxSteps);

if(flag1)
{
Serial.print(Speed);
Serial.println("Kmh");
lcd.setCursor(0,0);
lcd.print("RPM: ");
lcd.print(RPM);
lcd.print(" ");
lcd.setCursor(0,1);
lcd.print("Speed: ");
lcd.print(Speed);
lcd.print(" Km/h ");
flag1=0;
}
int currSteps=Steps;
int steps= currSteps-preSteps;
preSteps=currSteps;
myStepper.step(steps);
}

int readRPM()
{
if(REV >= 10 or millis()>=st+1000) // IT WILL UPDATE AFETR EVERY 10 READINGS or 1 second in idle
{
if(flag==0)
flag=1;
rpm = (60/2)*(1000/(millis() - time))*REV/bladesInFan;
time = millis();
REV = 0;
int x= rpm;
while(x!=0)
{
x = x/10;
RPMlen++;
}
Serial.println(rpm,DEC);
RPM=rpm;
delay(500);
st=millis();
flag1=1;
}
}

void RPMCount()
{
REV++;
if (led == LOW)
{
led = HIGH;
}
else
{
led = LOW;
}
digitalWrite(ledPin, led);
}