Cleaner bare bones Metronome.

const int onecount = 52;
const int othercount = 53;
int metronome;
#include <SoftwareSerial.h>
#include <TimerOne.h>
int metVal = 120;
int mval;
int delaycount = 0;


void loop() {
  digitalWrite(othercount, LOW);
  digitalWrite(onecount, LOW);


  GETMetVAL();

  //GetmetVal should retrun the pot value to metronome

  //TimerOne interval change here


  Serial.println(metronome);
}

void setup() {
  Timer1.initialize(1000000); // set a timer of length 100000 microseconds (or 0.1 sec - or 10Hz => the led will blink 5 times, 5 cycles of on-and-off, per second)
  Timer1.attachInterrupt( RealMetronome ); // attach the service routine here
Serial.begin(9600);
}

void RealMetronome()
{

  if (delaycount >= 4) {
    delaycount = 1;
  } else {
    delaycount++;
  }
  if (delaycount == 1) {
    digitalWrite(othercount, LOW);
    digitalWrite(onecount, HIGH);

  } else {

    digitalWrite(onecount, LOW);
    digitalWrite(othercount, HIGH);

  }
}

void GETMetVAL() {


  switch (mval)
  {

    case 0 ... 1023:

      if (analogRead(A2) < 10) {
        metVal = 10;
      } else {
        mval = analogRead(A2);
       metronome = mval;
      }
      //Math should be placed here
      //metronome = (equation here)
      // then reset the TIMERONE interval in the main loop.
      break;
    default:
      metVal = 130;
  }
}