i want to use a D4R-II together with APM2, PPM and RSSI are no problem. What i want to connect as well is
the serial port of RX and APM2 to send compressed GPS information over the FrSky data downlink to my antenna tracker. in principle i have that working, currently with an arduino pro mini evaluating an attached GPS sensor, compressing the GPS data and sending it over the downlink. So tweaking arducopters software to do that as well will be no big deal. I use NewSoftSerial with the arduino as it provides the inverted TTL signal, that is expected from the FrSky RX.
Question now is:
1) Can FastSerial in Arducopter 2.6 somehow be used for generating an INVERTED TTL signal?
2) Which Pins/Port should i use on the APM2 to connect the FrSky RX serial port?