title: Disable/enable interrupt (time) when an input is pressed on/off
body: <p>will clearing interrupt/breaking the loop then setting the interrupt, resume the ISR ?
  I am still new to formatting, so i'm unsure if this will do it.</p>
  
  <pre><code>else if(serial_input == 'p' || serial_input == 'P') {
  
      while(serial_input = fgetc(stdin)) {
          if(serial_input == 'p' || serial_input == 'P'){
              cli();
              break;
          }
          sei();  
      }
  </code></pre>