PC-to-R/C Interface

futaba

Risto K?’s PC to R/C interface let’s you connect to your Futaba radio transmitter. You can use this device to do direct control of your R/C project: prewritten trajectories, user called macros, or direct PC joystick control. He’s built two versions. The original one used multiple D-latches. The second version was an attempt to reduce the number of components. It uses interrupts in the microcontroller software instead of the latches. This would normally cause a lot of jitter, but Risto implemented the interrupts in assembly. The controller can handle up to 16 channels. The LCD displays the last pulse-width and channel.

[thanks Will]

18 thoughts on “PC-to-R/C Interface

  1. Just goes to show how windows has screwed us over; I have a cable that uses a single transistor and a few caps/resistors to connect a futaba radio to a serial port (which works under win98); but with xp’s new serial port interface you need to use an external processor to make it work :(

    Good way to get around it though! Most of the other designs I have seen use the joystick port hard wired to the joysticks, this is a much more plug&play solution…

  2. “You can use this device to do direct control of your R/C project: prewritten trajectories, user called macros, or direct PC joystick control“

    Excuse me, I`m a novice with electronics… (I don`t know where else to ask, and I read here everyday) does this mean this could be a direct itermeadiary between, say, a joystick and a servo, with no PC needed? I am working on such a project now, trying to find a way to directly control a servo with either a joystick or a gyroscopic mouse, for a hand tracking turret, with no PC in between (this is a mobile rig). Would this work for that this? The article didn`t make it clear for me.

  3. All that this device does is allow you to control a remote control using your computer. It is like you can move the joysticks on the remote by sending commands from the computer.

    It does not connect directly to the servo, it connects to a transmitter which connects wirelessly to a receiver which the servo(s) are connected to.

    It is very easy to control a servo with a microprocessor directly; you just send a pulse between 1 and 2 microseconds long to it. If you want it to go full left you send a 1ms pulse, and if you want it to go all of the way right you send a 2ms pulse; to make it center you send a 1.5ms pulse. So if you wanted to use a gyroscopic mouse you would need to write code that takes the signal from a mouse and converts it to the pulses for a servo (not an easy task)

    If you just want to use a joystick you best bet would be to get a cheap set of transmitter and receiver from your hobby store (should cost like $30), and take the circuit board from the remote and attach the joystick’s variable resistors where the remotes were.

  4. Hey, thanks! That was very helpful- I was almost sure there would be no way to do a gyroscopic mouse to servo go between without a computer and mouse tracking software, but you’ve explained to me it can be done- I had no idea pulse controls existed innately in servos. In that case, using pulses to control servos, they can only go to the extremes of left and right, and center, or can these pulses be used for incremental movement for precision servo control for a tracking base?

    Thanks again, if I find out better how this can be done, if it can be done, without a PC in between, I will go off to study this stuff in depth until I make it work. Sorry to hijack the comments thread…

    If I get this to work, I will definitely submit it to hackaday with a full build report, including the new laser targeting system I have already designed.

  5. you can give it any pulse you want, like 1.25ms for 1/4 left, 1.345ms for a different position, etc (ahh, the joys of analog). If you want it to move a long distance (like >5degrees) you have to send the pulse a few times with about a 20ms delay in between each one to allow it to move. Try downloading the manual for the basic stamp 2 from parallax, it has a ton of info about driving servos.

  6. Ha this is awesome! Add a wireless camera and an Estes “Mosquito” model rocket to your plane, hook up the camera receiver to the same PC, and now you can VNC into your machine to launch your plane!

    I imagine hobbyists with model air forces on the roofs of buildings all over the world, ready to deploy at their master’s bidding.

  7. Ha this is awesome! Add a wireless camera and an Estes “Mosquito” model rocket to your plane, hook up the camera receiver to the same PC, and now you can VNC into your machine to launch your plane!

    I imagine hobbyists with model air forces on the roofs of buildings all over the world, ready to deploy at their master’s bidding.

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