MEGA 2560

I'd like to use an external interrupt DIN (on pins 2 (interrupt 0), 3 (interrupt 1), 18 (interrupt 5), 19 (interrupt 4), 20 (interrupt 3), and 21 (interrupt 2) for triggering some Digital OUT. 1. What is the minimum duration for external pulse to recognize it 2.During what time after recognizing the external pulse arduino can rise an D OUT

The minimum pulse duration is in the datasheet of the ATmega2560. http://www.atmel.com/devices/ATMEGA2560.aspx In the Complete datasheet : "Low level interrupts and the edge interrupt on INT3:0 are detected asynchronously.". I can't find what that means for the minimum pulse :(

This is for the normal interrupts : https://www.arduino.cc/en/Reference/AttachInterrupt Beside that are also "pin change interrupt" pins.

This is about interrupt timing (for an Arduino Uno) : http://www.gammon.com.au/interrupts

Perhaps you need extra hardware ?

Table 15-2 pg 110, ~50 ns pulse required for asynchronous detection.

Table 15-2 pg 110, ~50 ns pulse required for asynchronous detection.

That is correct… UNLESS the processor is asleep. Then, an external interrupt will wake up the processor, but the wake up time (defined by the SUT and CSEL bits) has to complete before the interrupt will be acted upon.

if processor is awake:
_____    ______
     |__| <--- external interrupt 
  -->| 50 nsec max
______|<-
      |<--- processor services interrupt


if processor is asleep:
_____    ______
     |__| <--- external interrupt
  -->| 50 nsec
______|<-
      |<--- processor begins wakeup
      |
      |<------ SUT and CSEL delays ------>
__________________________________________|<--- interrupt serviced
                                          |__________