I want to drive servos over long runs, say 20 feet? Or more. Is that feasible? Can I boost the signal from the wixel so it will go that far?
That sounds kind-of far, but if you use high-quality twisted pair, or coaxial, cable, it might work. Try a Cat-6 Ethernet cable, or a TV antenna cable perhaps.
You can also get a RS-485 driver and receiver circuit, and use that to modulate/de-modulate the signal for the long run. This requires two wires (three, if you also want ground.)
digikey.com/product-detail/e … -ND/571332
Well, once Martan has posted on Wixel section, i dont think that he want to do it wired.
Anyway, David posted some servo apps samples on github:
Also, SladeCraven did a great job playing with the registers to increase the Wixel range, here:
It´s only ideas… Probably David or some other employee could give you a better answer.
Well, actually I did want to know about wired. (But I also was interested in increasing the wixel range, so thanks for that too) Since the wixel isn’t specifically made to do servos, I figured I’d ask here rather than on the servo forum.
My application is a central wixel talking to multiple wixel slaves (I’m working on the wixel apps for that now)
I’d have, say 10 slaves, each has up to 6 servos. Each servo then may or may not be far from the slave, I was just looking for the max I can expect in terms of distance from the slave to the servo.
Power is not a problem, I can do an amp or more at each slave, I was worried about the actual control signal to the servo and how far that can go over a wire and still get reliable control.
I was thinking some sort of ‘buffer’ chip or other fairly simple (cheap) solution to get it to go further?
Anyhow, thanks for the replies, I appreciate the help!
Honestly, for 20 feet, I think a cat6 twisted pair will be sufficient.
If that somehow doesn’t work, then the RS-485 interface chip is a kind of “buffer chip” – except you need the same chip on the receiving end, too.
RS-485 can be run up to a kilometer over twisted pair at the typical data rate of a servo PWM control signal.
If you want a buffer chip only at the sending end, a 5V opamp such as the MCP601 would probably work well. Tie the “+” input to your output pin, and your “-” input to a resistor divider sitting at 1V, for a good thresholding circuit. (MCP604 has four of them in one package if you need to buffer many of them.) It can drive 22 mA from the output (assuming it’s driven by 5V – at 3.3V it looks like about 16 mA.)
There are also specific logic buffer chips, although those are more common for TTL than for CMOS, at least in through-hole, from what I’ve experienced. Although a simple OR gate would probably work fine, too
Thanks! I’ve got my master/many slaves wixel code working, so this weekend I’ll hook up some servos and see how far I can get.