How short (ms) can a edge be?

Hi,

if I want to put an interrupt on a falling/rising/changing edge on a digital pin on the Arduino Uno board, how many ms does the falling/rising have to be in order to be detected?

Way under a mS, IIRC it's maybe 2 clock cycles, that's about 130nS.

EDIT: OK I just looked it up, PCIs take 3 cycles (195nS) and I can't find info on the external ints but they are asynchronous so may be even faster.


Rob

I only have the datasheet for the 640/1280/2560/2561 - but Atmel says the minimum pulse width for an async external interrupt is 50 ns.

zzzz: if I want to put an interrupt on a falling/rising/changing edge on a digital pin on the Arduino Uno board, how many ms does the falling/rising have to be in order to be detected?

I suspect you are trying to asking a different question than what you are asking. Edges with an edge rate rated in "milliseconds" is a very slow edge.

trying to asking a different question than what you are asking

I think so, I read between the lines and assumed he meant the minimum pulse width that will be detected as the "edge" from most devices will be much faster, maybe just a few nS.


Rob