LCD not working

[Yacovrex]

Why is the LCS Screen with i2c not working?

int ledPin = 13;                // IR LED connected to digital pin 13
volatile byte rpmcount;
unsigned int rpm;
unsigned long timeold;

#include <Wire.h>
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x20,16,2);

void rpm_fun()
 {
   //Each rotation, this interrupt function is run twice, so take that into consideration for 
   //calculating RPM
   //Update count
      rpmcount++;
 }

void setup()
 {
   lcd.init();
   lcd.backlight();

   //Interrupt 0 is digital pin 2, so that is where the IR detector is connected
   //Triggers on FALLING (change from HIGH to LOW)
   attachInterrupt(0, rpm_fun, FALLING);

   //Turn on IR LED
   pinMode(ledPin, OUTPUT);
   digitalWrite(ledPin, HIGH);

   rpmcount = 0;
   rpm = 0;
   timeold = 0;
 }

 void loop()
 {
   //Update RPM every second
   delay(1000);
   //Don't process interrupts during calculations
   detachInterrupt(0);
   //Note that this would be 60*1000/(millis() - timeold)*rpmcount if the interrupt
   //happened once per revolution instead of twice. Other multiples could be used
   //for multi-bladed propellers or fans
   rpm = 30*1000/(millis() - timeold)*rpmcount;
   timeold = millis();
   rpmcount = 0;

   //Print out result to lcd
   lcd.clear();
   lcd.print("RPM=");
   lcd.print(rpm);

   //Restart the interrupt processing
   attachInterrupt(0, rpm_fun, FALLING);
  }

[trag1c]

Context would be helpful. What are you using to control your lcd. Pi, CHIP, Arduino ect.

[Yacovrex]

arduno uno