Capturing timer value based on external interrupt , leveraging the 62.5nsec (16MHz) resolution) of the ATMEGA328 on the Arduino Uno

[blh64]

@cattledog

The official way to write an empty interrupt vector is shown here
(avr-libc: <avr/interrupt.h>: Interrupts)

which also states:

If an unexpected interrupt occurs (interrupt is enabled and no handler is installed,
which usually indicates a bug), then the default action is to reset the device by
jumping to the reset vector.

Seems kinda familiar...