I have tied the reset line of my Mega 2560 to a GPIO pin (A15) so that I can programatically reset the unit. This allows me to reset the device over the network, and it works a treat.
However when the reset line is tied to A15, this prevents me from being able to upload code. When I hit upload in the IDE, the TX light on the Mega doesn't flash as usual, and IDE returns the following error:
avrdude: stk500v2_getsync(): timeout communicating with programmer
When I remove the wire between reset and A15, the upload succeeds.
I hit a similar problem when I tried to tie the reset line of my W5100 breakout board to the Mega's reset line. Never really resolved it, other than using another GPIO pin to reset the W5100, which works ok.
Can anyone suggest a reason / solution for this?