nigeljohnson73:
Hi thereMy project is using an optoisolator package with a couple of spare channels. I was wondering if I were to use a channel to connect the reset to ground by setting a digital pin to HIGH.
What happens to the HIGH digital pin as the board resets? If it stays or goes HIGH at any point I guess the board will continually reset?
Early in the reset process all the I/O pins go to high impedance input mode, so you lose the digital high and the reset process isn't long enough to insure a proper reset process. Atmel recommends against trying to cause a reset based on using only a output pin to initiate the process. This topic comes up surprisingly often so there are lots of posts you can research if you wish more details.
Is there a way to wire up some form of interrupt to the power supply provided externally to the VCC pin on the power jumper? I was thinking a relay or something, but the same problem would exist about the trigger pin staying HIGH.Yes, that would not solve the timing problem. One possible solution is to have a output pin initiate a 555 timer chip to generate the reset pulse with enough length to insure the proper reset process is completed.
Now is the time where one of the usual cast of software gurus would ask you why you need to initiate a reset as that is usually a case of not having proper program structure to begin with, as there is usually never a real need to perform a hardware reset that can't be solved by proper software?
Lefty