I'm creating a LCD frequency generator.
TIMER1 reaches a set value, it's set to toggle Pin 9 (via
Accidentally, I left the
TIMER1 "interrupt on compare match A" enabled, but never defined the
TIMER1_COMPA_vect interrupt vector.
This made the Uno reset itself - but not running through the bootloader, just the program part - whenever
TIMER1_COMPA_vect would've been called.
Once I defined the ISR, even without it having any content, it would run as expected.
Is there a default content for ISRs, which resets the device / starts just after the bootloader? Shouldn't the compiler detect a completely missing ISR?