Hi, I have the code attached here for testing a 3digit 7 segment display and some pushbuttons. I use an interrupt routine to update the display, manage blinking and debouncing buttons. The program should just change the value on the 7 segment display when pushing a button (falling edge on the pin). Code is working if I put a delay(0) within my while loop (line 87). Without the delay(0) the code in the while loop is doing nothing (it also works if I eg. put random(0) iso. delay(0) ) Looks like the compiler is ignoring the code in the while loop for some strange reason.