Hey guys. I've got a question about the hand-held gps units used with ultralights. One of my coworkers recently finished a vans rv-6a, and apparently his efis/ahrs system interfaces with his gps via a two-wire connection, and the gps just sends raw NMEA data down that, which the aircraft uses to position the flight director bars and display other information.
Now I haven't seen this myself, but the coworker who mentioned it is reliable with that sort of thing (He's my boss, avionics LAME, and he installed the avionics on the rv, so he ought to know). He also mentioned that one of the pilots flys some kind of ultralight, and that he wants a minimalist FD system for his aircraft. I think I can do it, maybe, but it all hangs on what kind of data the gps unit can send. I've only ever seen hand held gps units with PC serial or USB ports, not a NMEA port.
The vague idea I have in my head is a picaxe chip monitering the data stream coming from the gps (specifically the data from $GPXTE), and convert the distance and L or R components of that sentence into a binary figure, which can be sent to a binary decoder, to drive a series of LEDs. The middle LED means you're on track, and the LEDs on either side mean fly left or right. Possibly I could also have it sniff for $GPAAM, which is a waypoint arrival alarm, to flash a separate light too.
Of course I have no experience with picaxe, so my chances are slim - and it doesn't help that the picaxe forum apparently doesn't like me even before I sign up...
But anyway, have you guys, who have used aeronautical handheld gps units, seen such a data port?
Thanks :)