1602 LCD and reading out RPM fan

Other Hardware LEDs and Multiplexing
4

The problem is that the sketch I use for now, uses the 2 - pin of the arduino.
Because of me wanting to use more fans I want to use the A0 to A5 pin to read out the rpm.
But I don't know how, so that's the biggest problem :stuck_out_tongue:

For now I have it working so far: (rpm on pin 2)

#include <LiquidCrystal.h>

volatile byte half_revolutions;
unsigned int rpm;
unsigned long timeold;
LiquidCrystal lcd (12,11,7,6,5,4);
void setup()
{
  Serial.begin(9600);
  attachInterrupt(0, rpm_fun, RISING);
  half_revolutions = 0;
  rpm = 0;
  timeold = 0;
}
void loop()
{
  if (half_revolutions >= 20) { 
    rpm = 30*1000/(millis() - timeold)*half_revolutions;
    timeold = millis();
    half_revolutions = 0;
    if (rpm >1000){
      lcd.setCursor(0,0);
      lcd.print(rpm,DEC);
    }
    if (rpm <1000){
      lcd.setCursor(1,0);
      lcd.print(rpm,DEC);
      lcd.setCursor(0,0);
      lcd.print(" ");  
    }
    if (rpm == 0){
      lcd.setCursor(0,0);
      lcd.print("    ");
      lcd.setCursor(3,1);
      lcd.print("0");
    }
  }
}
void rpm_fun()
{
  half_revolutions++;
  //Each rotation, this interrupt function is run twice
}