I am looking at detecting a very short pulse, about 60ns.
I can pass the pulse through a One-Shot to widen it, but I was wondering what is the shortest pulse detectable
using an interrupt pin on the UNO?
Or is it solely an edge trigger thing only?
Larry
The pulse has to last the period of a clock cycle to be reliably detected so at 16MHz it is 62.5nS.
I can pass the pulse through a One-Shot to widen it
Yes.
See 13.2 in the datasheet for external interrupts:
The External Interrupt 1 is activated by the external pin INT1 if the SREG I-flag and the corresponding interrupt
mask are set. The level and edges on the external INT1 pin that activate the interrupt are defined in Table 13-1.
The value on the INT1 pin is sampled before detecting edges. If edge or toggle interrupt is selected, pulses that last
longer than one clock period will generate an interrupt. Shorter pulses are not guaranteed to generate an interrupt.
If low level interrupt is selected, the low level must be held until the completion of the currently executing instruction
to generate an interrupt.
Thanks guys.