ArduPilotMega + Spektrum satellite Rx -- NOW AVAILABLE

Hi guys. Here's a little experiment we did yesterday using Doug Weibel's spektrum-to-PPM substitute firmware for the APM's ATmega328P, an upcoming (now available here!) Spektrum Adapter accessory board, and an ArduCopter. Sorry about the lack of video, but I can assure you our resident quad pilot Jeff Taylor flew this here at the shop with good results (considering none of this is fully baked)!


The Spektrum Adapter accessory powers the Spektrum module with an on-board 3.3V regulator, takes care of level translation on the single serial line, and has an input pin to enable/disable the regulator (this is used for putting the satellite in bind mode). The four pins are GND, 5V, data, and regulator enable.


I wrote a (very) crude sketch to put the satellite in different bind modes, you can grab it here: I've tested it with DSM2, DSMX, and Orange Rx satellites. I've found that "DSM2 1024/22ms" mode is the one that works with Doug's firmware. The sketch is meant to be used on any Arduino Mega style board, it uses Tx1 to enable the regulator and consequently the satellite at the right moment to then receive the bind mode pulses sent out through Rx1. Once the sat is in bind mode, Rx1 is configured as an input again to receive the serial data after binding.

The ATmega328P needs to be re-programmed with Doug's firmware. You can either Arduino-ify the chip with the right bootloader and load the sketch through an FTDI cable connected to IN1 and IN2, or take the easy way and verify the sketch, grab the .hex file, and load it with an AVR ISP programmer.


Once the sat is bound, I soldered the adapter board on to an APM as seen in the photo, directly on the three IN1 pins. IN1 is the 328's Rx and is the only pin needed to receive the satellite's channel data. The small blue wire in the photo is connecting the 5V and reg enable pins to keep the regulator on at all times. The 328's Tx line could also be set high at all times to do the same thing, maybe the binding modes can be integrated into the 328 firmware as well?


After this, all should be the same as when using the full Rx module with servo extension cables. We found no problems with this setup during the Mission Planner configuration steps.


The Spektrum Adapter boards are now in stock in the store! Feedback for future revisions is welcome, and happy hacking!

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Comment by Sebastian Gralla on August 19, 2011 at 2:12pm

great, that's what I was waiting for! :)

Comment by Jeff Taylor on August 19, 2011 at 3:27pm

This is really cool, I think this is how I'll be flying all my gear when it's ready. There was no difference from a normal radio receiver setup.

Comment by Doug Weibel on August 19, 2011 at 8:22pm

Hey Sam,  was I supposed to make a post about this quite some time ago?  Sorry - too many projects in my shop.  Anyway I'm glad to see it is about ready for the store ;)  I have used one of these boards for full HIL and it worked great, and have been meaning to stick one in my SkyFun and fly with it, but keep getting sidetracked.

Comment by Yves Gohy on August 19, 2011 at 11:44pm

Hello, I also thought this type of satellite, the Jeti RSAT 2. it is configured with the JETIBOX I think, to be used on the Mikrokopter.

Comment by Björn Pettersson on August 20, 2011 at 2:27am

Jeti RSAT would be nice (Jeti user here too), I believe it is sending a ppm pulse train as is is so might be even easier to do?

Comment by druckgott on August 20, 2011 at 2:46am

very well pefekt

Comment by Björn Pettersson on August 20, 2011 at 3:05am

Oh, see a ppm sum passtrough is implemented Birkeland's Blog

Comment by Alex McEwan on August 20, 2011 at 2:00pm

Love the idea but only one satellite ? For a better range with more robust comms would it not be better with more than one.



Comment by Sam Kelly on August 20, 2011 at 2:50pm

Alex, of course more than one would work better, and it would require a little diversity setup. This is just a proof of concept though, I don't think I've seen anyone mention that they've flow an APM with just spektrum sats (I could be wrong though, didn't google this extensively). Thanks for the suggestion!

Comment by george on August 21, 2011 at 12:54pm

So if I understand correctly I won't need the rats nest of wires between my receiver and autopilot?! That's great!


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