RC USB adapter
 

Time to share a little project I'm working on - it's a "how do you over-engineer this thing" type of project.

Compact 4-channel RC receiver to USB adapter, so you can use your radio gear to drive computer apps. The first software stack provides 2+1 channels (two fully proportional and one digital channel - works with a popular RC sim), but the software is easily updatable (eg: 4 proportional channels for say, a flight sim - this is WIP). It's custom-built from the ground up using dual contemporary microcontrollers with some fancy specs:

• Full speed USB
• USB-C connector for "plug it in either way" fweedom
• 16-bits of data per channel
• better than 0.1uS resolution on all 4 channels
• drag-and-drop software update
• Comfortably processes all 4 channels at better than 500FPS

It can be used to play simulators, but I'm also hoping to use it to capture/record radio inputs "live" for later analysis or maybe even do overlays. Conceptually these things are do-able, but I'm gonna have to up my desktop app programming skills. These later goals also assume I can get out to the track anytime in the near future :)

https://cimg8.ibsrv.net/gimg/www.rct...4bcf9962c7.jpg

Nice project, I've been drawing something similar using a PSOC dev board, but since I've got a VRC dongle the project has lost priority. Stil I need something at least 4 channels for plane sim. As a suggestion for lowering the wiring, I think just one +- connection is enough, and signal for each data line.

I made one with an Arduino Micro Pro. Works great with VRC Pro

I'm not quite sure what this offers vs my Arduino based board except for improved timer resolution, but at 0.5us that's still only a 0.03% margin of error. Mine reports at around 1000fps.

What micros does that board use?

I'm using a combination of an RP2040 and one of the Microchip DB series. As I said, over-engineered. The ability to swap software without any programmer is kind of handy. It just presents a virtual drive (eg "E:") that you can just drag the software onto. Makes it trivial to change configurations. The USB-C connector was a late addition, but works quite well.

Not sure I follow - it has +/- & 4 data lines?

Yes, but it looks like that's what you've implemented already.

I wasn't very clear. If the photo shows a 2 channel interface, I see 6 wires = 2 x servo link (+ - data). You can have just 1 'complete' wire for channel 1 to power the RX, and just add the data line for every next channel. For 4 channels the breakout wiring would 1 complete (3 wires) + 3 more channels = 6 wires. Hope this makes clear my suggestion.

Ah, ok. The photo shows 4 channels. Power on the two near side (marked GND and 5V) and then the 4 channel signals. The wiring is how you describe it, with one 3-wire plug and 3 single-wire plugs.

Here's a different picture.

https://cimg0.ibsrv.net/gimg/www.rct...f692c515b2.jpg

Is this something you plan on selling? I’d love to play a racing game on my computer with something like this

Any particular reason you are building your own vs buying one of the existing ones?

Well, a) this seems like a cool project to work on if you’re a tinker, and b) it’s been a while since I’ve actively searched for one, but are there any out there that aren’t either sold out or discontinued at the moment?

I personally have been wanting to try playing VRC with my radio for a while now, but it seems that every time I get the itch to try and find a USB adapter, I can’t seem to get my hands on one for the reasons above. Last I heard, MonacoRC was going to release one, but I haven’t followed up on it (I’m in the US, BTW).

I'm making a limited number available for people. Parts availability is challenging at the moment with the semiconductor supply issues. Details here: https://www.tindie.com/products/phat...c-usb-adapter/

A fair question! I learn stuff by doing and testing out ideas. I've put together Pro Micro-based ones and built some atmega32u4 ones from scratch with custom designs. Testing concepts and doing electronic assembly with QFN parts at home pushes my limits a bit (first time I've used 0402 passives too), but it's all good fun. The easy software update part is unique as far as I can tell. Also, the board has places for programmable flashing lights. Can never have too many flashing lights. This was good opportunity to explore the multi-microcontroller approach (one good at USB, one good at signal capture) and learn a bit about using USB-C (still plenty to learn there on the power side, though). The package has potential outside of gaming.

It's a big motivation: I do this for fun and happy to help people out. There are plenty of guides for implementing an adapter with readily available generic boards (here's one I wrote a while back: https://github.com/grandaspanna/RC_ReceiverAdapter), but not everybody wants to be sourcing the bits, soldering, installing software IDEs, pulling hair out while things don't work etc.

Is this able to use the AUX channels for resetting the car or going back to pits in VRC? I built my own, but can never figure this part out

Yes - this is the behaviour of the default software. It monitors a third channel and presses a button when used. You can choose this button in VRC Pro to marshal the car.

As a complete aside, the default channel 3 behaviour on different radios varies wildly. My Futaba 3PV defaults to hard right at rest, whilst my M11X is midpoint. Both lengthen the pulse width when activated on the controller (these things can be configured, but modern radio manuals need cryptographic expertise to decipher). A friend's M17 starts midpoint and shortens the pulse width.
He kindly did a little video to show: