Tachometer - Arduino Uno code

#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET     -1 // Reset pin 4 (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define interrupt_pin 2

unsigned int rpm;
volatile unsigned int counter = 0;
unsigned long passedtime = 0;

void draw(unsigned int _rpm) {
  unsigned int cnt;
  cnt = counter / 6;
  display.clearDisplay();
  display.setTextSize(2);             // Normal 1:1 pixel scale
  display.setTextColor(WHITE);        // Draw white text
  display.setCursor(0,0);             // Start at top-left corner
  display.print("RPM:");
  display.setCursor(0,16);
  display.print(_rpm, DEC);
  display.setCursor(0,32);
  display.print("Hz:");
  display.setCursor(0,48);
  display.print(cnt, DEC);
  display.display();
}

void isr() {
      counter++;
 }


void setup() {

    display.begin(SSD1306_SWITCHCAPVCC, 0x3C);

    display.clearDisplay();
    display.setTextSize(2);             // Normal 1:1 pixel scale
    display.setTextColor(WHITE);        // Draw white text
    display.setCursor(0,0);             // Start at top-left corner
    display.print("START");
    display.display();
    attachInterrupt(digitalPinToInterrupt(interrupt_pin), isr, RISING);
    passedtime = millis();
}

void loop() {
  if ((millis() - passedtime) > 2999){
    detachInterrupt(digitalPinToInterrupt(interrupt_pin)); //Interrupts are disabled
  //  noInterrupts();  no working
   rpm = 10 * counter;   //   60 * counter(12) / 2 / 3
   draw(rpm);
   counter = 0;
   passedtime = millis();
   attachInterrupt(digitalPinToInterrupt(interrupt_pin), isr, RISING);
  }
}