Well, sort of familiar ....Can set up OEM codes to inputs and played a little with basic Macros, but unfortunately that is about it. With this I can see your point, that is very clever, and it does sound quite easy in principle, but if we were to go with a macro then it would have to be triggered (I don't know how a brain would handle it!).
I do have one spare input pin, so if I couple that to an edge trigger on the MPG so as to pulse the spare input on each transition, that could call the macro to update the FRO. I'll get on to it and see I can come up with.
BTW, what is the best way to trigger a Macro from an input transition??
Cheers