Yeah I do need to reverse engineer it I guess, yeah it transfers depth, water temp etc to a computer program, there is communication between the program on the pc and the dive computer at intervals is all I know really. Someone has built a device which can do this with analogue components but there were issues with the timing which is why I figured a pic at the middle would make things much easier. Here was the comment
It is a simple but odd protocol. Most IR
communication(like TV remote controls) use a
protocol that allows an effective AGC circuit no
matter what binary data is sent, i.e., there's just
as many blips for a '0' as a '1'. But the Mares
encoding scheme just keys an oscillator with the
bits out of a UART. The only reason it works at
all is that it only sends the characters 0-9, A-F
and '<''>' which have enough 0's and 1's in them
to keep the AGC happy.