I had originally intended to utilise the unused Port D pins, ie Digital Pins 3, 4, and 5, but found I wasn’t getting reliable operation. Changing to Port B pins fixed the problem, and I’m also using the Port C pins without a problem.
It’s not immediately apparent to me why, but I can only assume TV-out is messing with them. Given it looks like the Hackvision happily uses these very pins, is there something in the overlay code that might be causing the issue (mine is an overlay application)? Otherwise do I have some sort of interference going on?
Also, because I’m only really interested in an overlay application, does this mean I can use Pin 9, or is that tied up?