I have some noobie questions about running two RC transmitters in trainer / buddy-box mode...
The transmitter I have on hand is a Futaba 7C FASST 2.4GHz rig. A second identical unit could plug in and work as a 'trainer' and would be ideal. Problem is, that's a lot of money spent for limited usefulness so I'd like to avoid it.
Plan B, considerably cheaper than a second 7C, would be getting a pair of more reasonably-priced transmitters. That option means swapping out receivers. Not a big problem but inelegant.
Getting one other brand of transmitter on hand would allow comparing the signals on the scope. There are no other RC people here to tap into unfortunately. (I suppose plan C is getting an order started with Hobby King since there is considerable lead time shipping here from HK... but which transmitter to test for compatibility?)
What I'm really wondering, does it makes sense to hack together a cable (and other electronics?) to match the Futaba box with some other transmitter? Are the trainer port signals anything alike between brands? If not, can the signals be massaged into a match (e.g., logic level shifter)? I can imagine that the signals are similar to I2C in that they need to be programmed into the system controllers. There is an interesting Wiki article on PPM which does not address trainer ports.
The 7C's 'trainer' port, the rectangular type, shows this pinout:
pin signal
1 n/c
2 GND
3 PPM OUT
4 Vcc, bat.+
5 Vcc (slave mode)
6 PPM IN
From Hobby King I got a trainer cable that mates with the 7C but has a round DIN plug (~12 mm round shell) on the other end. HK doesn't explain what the round plug mates with and there is no documentation. I assume it matches some other transmitter HK sells. Anyone know about that? I have another cable on order with the rect Futaba plugs on both ends (mostly so I can see how the signals are supposed to mate up).
Also I found a Futaba cable with a USB end to allow it run flight simulators, such as MSFS. The existence of such a cable seems to indicate that trainer port signals might have been standardized. Have been looking for such information online with no luck so far.
Any advice? I don't want to fry this box with a bad hookup.
I have a couple of friends with even less RC experience than me, if that is possible. I'd like to get them flying on a buddy box and maybe infect them with the RC bug.