Open Hardware RC Radios

A decade ago, RC transmitters were clunky, expensive and PCM. A decade before that, everything was analog. Now, RC transmitters are completely digital, allowing for hundreds of aircraft to take to the sky. They’re also cheap, thanks to engineers in China. Now, they’re open hardware, too.

An old Futaba radio outfitted with AR Uni electronics. Image source: vikar
An old Futaba radio outfitted with AR Uni electronics. Image source: vikar

An exceptionally long thread over on the RCGroups forums has been going on for a few months, extolling the virtues of the ‘AR Uni’ board that turns old transmitters into full featured digital radios. This board runs everything, from two analog sticks, a directional keyboard, pots galore, switches everywhere, and a fancy LCD that makes programming easy. The joys of Open Hardware, brought to RC geeks. It’s a thing of beauty.

Like the Turnigy 9x radio, this barebones radio module uses RF modules — backpacks that contain the radio. This is also Open Hardware, and it’s compatible with just about every radio protocol out there. It’ll talk to everything from a Hubsan quadcopter to a Spektrum DSM2 receiver, and it’s simple enough that it can be built on stripboard.

When it comes to Open Hardware, the effort shown in these two projects cannot be overstated, even though the authors and creators of these projects seem to ignore their place in the context of the last decade of Open Hardware. Combine these projects with a few of the quadcopter flight computers and receivers, and you have a completely open hardware flying machine.

25 thoughts on “Open Hardware RC Radios

  1. Now just need to sort out all the different standards for comms and connectivity to the flight controller – Satellite, DSM/DSM2/DSMX, S-Bus, PPM etc, and everything will be sweet :)

    1. Meh.

      While I agree that it would be nice to have one, excellent, universal standard, all of the transmitters take modules and any flight controller worth its salt can decode all of these (see Tau Labs/dRonin for example)

  2. Funny , I am actually flying most of my tiny ”toys” drones with an open hardware modified FUTABA that was using on the eighties ( same era as back to the future). Goebish, (Tilman’s link) made an excellent module for this type of open hardware rc called it the ”Doc Brown Special”. Most of the related work is on the deviation group: http://www.deviationtx.com/

  3. as recently as “just before the damn kid was born”, i used a PIC attached to the trainer port on my radio. it took in the PCM, applied some mixing/exponential/differential, and then generated new PCM. cheap radio modules make that seem primitive, i guess. someday, probably “just after the damn kid moves out”, maybe i’ll get to do a 2.0 using a digital radio module

  4. I guess actually I can credit the expense of R/C equipment back in the day as what got me interested in electronics. I got the plans for a homebrew digital proportional system, but then it turned out that the custom receiver IC and the TX and the servo parts cost the same as the finished products. I’m not quite sure what the cost effectiveness of it had been when the design was originated a few years before. Anyhoo, I was looking for a way to build one out of more general purpose ICs, that might be got surplus or salvaged. I figured I might have to design my own, so it was a start from basics deally and work my way up as I learned. I got hold of an old single channel TX and escapement and built a single channel TRF receiver… which seemed to work well. Then I got the miniature bug, and was messing around trying to make my own escapements/actuators, and also made a submini rx based on a ZN-414, crammed on a half inch square of stripboard….. I blame Howard McEntee’s articles about R/C CO2 power for that digression… but I could never get my escapement reliable enough, these were based on a rubber motor spring, something was happening where it would “fart” and let it all unwind…. was never sure if it was a problem with the escapement or RF interference, being a whippersnapper, my largest investment in test equipment was a moving coil multimeter. (And that was at least a months pocket money for the cheapest one Radio Shack had.) so poverty got in the way, then studying and poverty, then real life, so never got much further in my R/C adventures. It’s one of those hobbies now though, I get mad crazy about it for a couple of months every so often, but goes backburner for months too.

    Anyway, I’ll have to keep an eye out for some of the more ancient kit for the RF parts to glom some of these projects onto, good stuffs.

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