DIY Torquemeter - Device to Measure Dynamic Torque

#include <LiquidCrystal.h>
LiquidCrystal lcd(8, 9, 4, 5, 6, 7);

#include "HX711.h"
#define calibration_factor 2150.0 //This value is obtained using the SparkFun_HX711_Calibration sketch
#define DOUT  26
#define CLK  27
HX711 scale(DOUT, CLK);
const int irPin = A8;
int triggers = 0;
unsigned long elapsedTime;
int laststate =0;
const unsigned long sampleTime = 1000;
int rpmMax=0;
void setup()
{
lcd.begin(16, 2);              // start the library
lcd.setCursor(0,0);
lcd.print("MaxRpm:");
lcd.setCursor(0,1);
lcd.print("Torque:");
pinMode(irPin, INPUT);
Serial.begin(9600);
scale.set_scale(calibration_factor); //This value is obtained by using the SparkFun_HX711_Calibration sketch
scale.tare(); //Assuming there is no weight on the scale at start up, reset the scale to 0

}
void loop()
{
  
  int rpm=rpmGet();
  if (rpm > rpmMax)
  {
  rpmMax = rpm;
  }
  lcd.setCursor(8,0);
  lcd.print("       ");
  lcd.setCursor(8,0);
  lcd.print(rpm);
  lcd.print(" rpm");
  torque();
}



int torque()
{
  lcd.setCursor(8,1);     // move cursor to second line "1" and 9 spaces over
  lcd.print("        ");
  lcd.setCursor(8,1);     // move cursor to second line "1" and 9 spaces over
  float force = ((scale.get_units())/100);
  float arm = (28);
  int torque = (force * arm) ;
  lcd.print(torque);      // display seconds elapsed since power-up
  lcd.print(" Nmm");
  Serial.println(scale.get_units()); //scale.get_units() returns a float

}

int rpmGet()
{
unsigned long currentTime = 0;
unsigned long startTime = millis();
while (currentTime <= sampleTime)
{
int val = digitalRead(irPin);
if(!val)
  {
      if(laststate){
      triggers++;
      laststate=0;
                   }
  }
else
    {
      laststate = 1;
    }
    currentTime = millis() - startTime;
}

int countRpm = int(60000/float(sampleTime))*(triggers/2);
triggers=0;
return countRpm;
}