Hello Nick,
I managed to get hold of a UNO board (which works ok) and wired it to the Mega2560 according to your aforementioned post. I thought it wasnt working at first but just noticed the wiring for Mega 2560 is different.
I attach output of the program. Does that help?
Thank you,
Kuba
Mega_2560_r3_chip_detector_output.txt (29.8 KB)