This would be a great option as the Bluetooth connection to the radio saves a lot of time and is instant which means keeping more of an eye on outside rather than looking down at instruments. With it already working with autopilot and radio surely adding this option to the transponder would be an another fantastic addition to Skydemon!

A nice keypad pop up for numeric entry would be superb for those of us who have the 57mm hole type. 

As an example (my a/c in fact), the TRIG TT21/2 transponders do not have an RS232 capability.. But they do sport a 'spare' TMAP (RS485) interface between controller and transponder per se, to which in principle it should be possible to connect a similar Bluetooth/RS232 modem..  A discrete exmple of a suitable RS232/RS485 adapter for this is available from LX Nav, it seems. What is needed is for someone more capable than I to make a nicely engineered, integrated unit combining all this for transponders which is similar to that of the Prodimex and SDlink products for common radios having an RS232 interface.  Some other transponders seem to have RS232 interfaces inc Garmin and the more expensive TT31 from TRIG..

I would love to have this functionality in flight..