Does anyone know how to interact with a 5-wire servo? I would like to be able to read the commands to this servo (with my parallax propeller) and either pass through the signal or modify it. (I'm using the propeller to interface with standard 3-wire servos just fine.) I have not been able to find a good resource describing the operation of 5-wire servos.

If anyone has any information (or better yet, spin code!) I would appreciate it very much!!


Views: 4177

Reply to This

Replies to This Discussion

I've never heard of a five-wire servo. Where do they come from and what do they do?
Right, this sounds like quite a diif part.

Even the servos built for robotics don't usually have anymore than the standard 3 from R/C.
The 5-wire servo's are in my HobbyZone Supercub. From what I've been able to gleam from from some RC aircraft web sites, it appears that it is a dumbed down servo, where much of the servo's brains reside outside the servo in the RC aircrafts's circuitry. So apparently if I want to use this, I have to do some of the thinking for it. I'm more than happy to program in the logic, but I don't know what the logic is!
Ah. Those are unique to HobbyZone, and you're right that they're missing all the PWM intelligence. I wouldn't bother with them. Real servos cost about $10 each. If you're planning to turn your Supercub into a UAV, I think you're going to have a tough job of it. I'd start with more standard RC gear and planes--something like an EasyStar doesn't cost much more than the Supercub all told but it's a great UAV platform.
I don't personally own a SuperCub so I don't know it's layout but would it be possible to simply install "normal" servos? Using the 5 wire servos would probably take up a cog and why do that when it can be done for you on the servo?
Good point, and actually I do plan on installing regular servos. However, I wanted to re-use the existing HobbyZone receiver; to do that I need to interpret its output commands for conversion to regular servo commands.
I have the exact same problem on an RC car of mine. 3 are the potentiometer and 2 are the motor wires. If you feel comfortable with electronics, find and isolate the servo control circuit. It will be an IC that will have power a PWM signal, and the potentiometer signal going in and the output to the motor. Isolate this by using an X-acto knife to cut the traces and wire up a servo connector to the power, ground, and PWM signal. Just make sure first that the PWM range is the same.
Thank you for that idea, I'll look into this!
There's a "coming soon" listing at for an aerial camera / video camera that is X-Port compatible for Hobbyzone / Parkzone planes. I'm going to get one for my Super Cub when they are ready.
I have just seen a 4-wire servo.
The case was that the servo did not contain the electronics but that we have a single
board with receiver, servo-control and engine-control.
I was not able to interpret the commands from the servo port directly, however I did find a work-around for the Hobbyzone Supercub.

It turns out that all 3 channels (rudder, elevator, and motor speed) are modulated on one pin of the x-port thingy. There are four pulses (about 250 us wide) spaced about 1000 us apart on a 15,000 us period. The distance between the 4 pulses (the length of the 3 gaps) determines servo position, specified by about +/- 330 us). So this lower end receiver has less resolution (in my implementation) of servo range of motion (+/- 330, instead of the standard +/-500), but can be interpreted for output to standard servos by an on-board processor (Parallax propeller in this case).

One thing to be aware of is keeping track of which pulse corresponds to which channel. During some of the basic pulse detection routines, individual pulses can be missed resulting in your servo channels slipping or shifting. (It would be very bad if mid-flight your reciever confused elevator for rudder and rudder for speed!!!!).

I really like the SuperCub as a potential UAV platform, it is very stable, easy to fly, and it comes pre-formed with 2 very well sized hollowed out cargo bays. I'm sure I can always upgrade the batteries and motor when I get to that stage..

Yes, that is the PPM-Signal. That is what gets modulated to the carrier.
If you search for pxarc you will find some info on it and code to decode and
encode it (for the pxa270/pxa255 arm-microcontroller).

How where you able to find the right pin?

Reply to Discussion



Season Two of the Trust Time Trial (T3) Contest 
A list of all T3 contests is here. The current round, the Vertical Horizontal one, is here

© 2019   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service