I have submitted a pull request https://github.com/diydrones/ardupilot/pull/520 that adds Spektrum satellite support to the APM2.0/2.5. I know this was possible with the old APM1 and I've seen some people requesting this for the new APM.
I have tested it quite a bit on the desk, but not in flight, since I haven't completed my UAV yet (I wanted this to work first so it will be less of a cable mess). You are free to test it but I take no responsibility if it makes your UAV crash. This is my first contribution to an open source project so I'm not 100% sure about the workflow, but I thought I'd post here as well as adding a pull request, and hope that the right people can test it and verify that it works.
Note that you need some sort of adapter because the satellite is designed for 3.3V, a simple regulator should be enough, since 3.3V is still enough for the AVR to detect as high. I use a fancy adapter that a colleague of mine built, it allows me to connect 2 satellites for diversity and merges it to one output.
Connect a jumper between channel 3 and 4 to enable this mode. It currently does not work with 11 bit frames, and you may experience servo glitches when you have the the USB cable connected. See the pull request for more info.
Comments
Hi Jim, hope you are still here.
If you are can I ask if you ever asked your friend to make more of the diversity boards in this article. ?
If so, can you advise me who to ask and where to go. ?
Many thanks
Gary
Yeah Andy, my comment wasn't directed at you. The product you linked seems fairly similar to that adapter I'm using, only with more ports and an MCU, and no 3.3V regulator. I'm only building a EPP plane so I should be fine with 2 satellites. :)
Hi Jimmy, I realize this is not a ppm converter. I posted it in case anyone is building a large copter using a PX4. This is a way a way to get multiple satellites going. A single sat on a large carbon bird is not safe.
Ah, thanks for the info. I missed that this is actually a firmware change on the atmega32U2. Nice work!
Hi Sam,
The adapter in the picture is not doing any PPM conversion, it's just a regulator with some logic chips that switches the signal between the two satellites if one should lose the signal without requiring an MCU.
As you can see in the code I use interrupts to do serial "bit banging" to read the serial data.
Thank you for that link Andy, that looks like an excellent device.
Hi Jimmy, I noticed you didn't mention in your post that the adapter you are using between the Spektrum satellite receiver and the APM is converting the serial output from the receiver to PPM. It is not only a 3V3 regulator/translator. The PX4 reads the receiver's serial data directly, but the APM does not, hence the need for your adapter.
A single Spektrum satellite on a large carbon octo is a bit scary due to all the shadowing, but I found this and will most likely use it on my current build.
http://www.quadrocopter.com/Diversity-Controller-for-Spektrum-and-J...
Cheers,
Andy
Wow this is awesome! I think I am going to by a couple of OrangeRX satellite receivers just to have some for other projects, it would be very interesting to to try this, seems as if it would eliminate a couple of grams and some wire mess. Thanks for your contribution!
Thank you Tom,
I was thinking of APM, but I do notice SPKT IN on my PX4IO.
I'm definitely going to give this a try.
Currently using 3DR converter and I am sure this will work way better.
As you have already commented it is a power hog and keeps you from connecting via USB only.
Was planning on waiting for Taranis, but this seems a really good solution too.
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