Unfortunately, I don't think anyoyone has made a pin mapping diagram for the mega yet.
Check the mega schematic
for the ATmega1280.
For example, look at the top right corner of the 1280: You'll see a group of 8 pins, ATmega pins 71 through 78. These are labeled PAn
, where n
is 0 to 7. These are the individual pins of PORTA, along with their corresponding signals (conveniently labeled PAn
as well). Now look to the right a bit at JP1, and you'll find these signals again. The green text tells me these are arduino pins 22 through 29.