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Thread: PhatomX with XL430-W250 servos

  1. #1

    PhatomX with XL430-W250 servos

    I received a prototype PhantomX using the XL430-W250 servos as you can see in the picture:
    Click image for larger version. 

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    Which I am beginning to experiment with. Currently been spending most play time on Teensy 4.x beta and USB Bluetooth support.

    Earlier I built a version of the Phoenix code base that runs on the OpenCM controller using the Dynamixel SDK which I will be starting my testing with. The code was earlier setup to be able to handle both AX and XL servos (Protocol1 and Protocol 2) on either Serial1 and/or Serial3... I had done some testing with the Current PhantomX with AX servos with one leg setup as XL430 servos... So should be able to get something sort of walking...

    But in that code base I have not done anything specific to take advantage of Protocol2 yet. Like maybe remove the interpolation from the main code and have the servos do it, maybe ask all of the servos for information through Sync Reads...

    Some of the experimenting I want to do also includes trying to figure out some reasonable configurations of the electronics and input/output devices that maybe Trossen might consider as default configurations, that make sense and do not need any proprietary hardware that Trossen needs to support.

    That is what I would personally like to get away from is any usage of things like the Arbotix board which requires someone to maintain an Arduino Install, maybe likewise something other than the commander...

    Note: in the above picture, the setup is not complete, that is currently they have an RPI3 connecting to an OpenCM9.04 board with a DXL hub that connects to the servos. The main power goes into the power switch and connects to the HUB, the OpenCM board gets power through the DXL connection (hub has an xl320 servo connector on it that jumpers to the OpenCM board).

    What the board does not have yet is any way to power the RPI3. Also it does not have any Input devices... Although could connect PS3 or like controller using BT...

    So wondering if anyone has suggestions on what a couple of different configurations might be?

    I see two or three different suggested setups:

    Beginner/Entry Level

    Maybe what is there minus RPI3 - (openCM9.04, Hub).

    Question is what to use for Input? I have an XBee adapter I hacked up that can connect to the Serial2 of the OpenCM board, and then connects to Commander... This is what I will start with.

    But what if there are no more commanders, what input device makes sense? Personally I think the Robotis remote control is too limited (just 10 buttons, no analog ones...), that connects using their BT adapter.

    I think it is beyond entry level and not sure you can see off the shelf parts to connect up PS3/PS4 controller. In this configuration wish to avoid Linux setups (RPI). Other Bluetooth setups? Again probably not easily setup for beginner.
    Board with something like Arduino Host Shield 2? A second board like Teensy 3.6? ...

    What about sound and other IO devices?

    Other suggestions?

    More Advanced configuration

    Include something like RPI3?

    Do you stay using something like OpenCM board? Move up to OpenCR board, or use something like U2D2?

    How do you power the RPI3? Now with OpenCR, there is 5v take off that could power it... Or do you use a BEC?

    And again more on what IO devices to support.

    Again suggestions?

    More later...

  2. #2

    Re: PhatomX with XL430-W250 servos

    I've had great luck with the FS-i6S controller/receiver: The receiver actually spits out a simple protocol of reveived data over serial port, so you don't need to decode the PWM signals (plus you get 10 channels.)

    It has fairly long range, because it's intended for remote control airplanes and drones. It doesn't give you much of a back channel, though (just receiver battery level.)

    I think staying with the OpenCM board is the best option, unless you want to use something like a USB2AX straight from the Raspberry Pi. Or you could build a HAT for the Pi, which does both AX TTL bus interface and power; this lets you get soft power on/off and voltage monitoring, too.

  3. #3

    Re: PhatomX with XL430-W250 servos

    Thanks @jwatte,

    Looks like it could be a possibility. Probably would require a special wire connection to connect up to Serial2 and/or PWM/PPM...

    For me it is sort of an interesting question, of what would I like to use versus something that maybe someone like Trossen can package up...

    For me, I would probably go with a Teensy 3.x or 4 (in beta). Sort of nice running at 600mhz with USB support. A few of us are playing with the Bluetooth support and have PS4 working and some PS3... Right now trying to figure out why some PS3 clones don't work.

    I agree with you about sticking with OpenCM. Currently I am getting the impression that the USB2AX may have been discontinued. They are and have been out of stock, or no longer listed at places like Seeedstudio and Trossen. Which is why I mentioned instead U2D2.

    OpenCR is a nice (expensive) board, that also would take care of battery stuff, plus you can turn off the power to the servos, and has gyro and accel, which Robotis uses in places like Turtlebot3 and some of their humanoids, etc, and they have setups to work with ROS and ROS2, which again is a good option.

    And their new XEL Network (, could be interesting, but currently their main connection is through ethernet, I believe they are working on an wireless setup as well.

    Thanks again, Who knows maybe I will pick up on of those controllers and play

  4. #4

    Re: PhatomX with XL430-W250 servos

    The U2D2 (and, to be fair, the USB2AX,) both are kind-of expensive for what they are: A $2 chip on a board with some connectors.
    Sure, the market might be only a few hundred, so you'd need a fair bit of margin for development, but still ...

    Separately, at a $50 target, a HAT for a Pi that supports both power and interfacing, might be quite interesting IMO. It might also support the RC receiver, if those chips are easily available (I haven't looked into this.) Turning power on/off to the servos is $2 for a MOSFET and a driver (I actually built this into my own boards.) Accelerometer/gyro is interesting, because the qty 100 price at DigiKey for something like the MPU9050 is higher than the price of a complete board delivered with postage from China ... So, soldering one of those onto the hat might be the right choice!

    I personally am underwhelmed with BlueTooth because of the finicky connections and the short range. I wouldn't take BlueTooth to a Mech Warfare bout ...

  5. #5

    Re: PhatomX with XL430-W250 servos

    Hi @jwatte,

    I agree with you that U2D2 ($50) is overpriced, likewise if it was still available, the USB2AX ($40):
    Note: I actually don't have a U2D2 nor their earlier USB2Dynamixel.

    And I keep having to remind myself, that what I am hoping for is configurations, that hopefully uses supported parts, such that takes as little support...

    So on surface the U2D2 looked nice as it can support communications up to 6mbs, supports both TTL and RS485, Robotis supports it, so users can use Robotis software including Dynamixel Wizard to recover firmware of servos...

    Again at entry level I personally think we should stick with OpenCM9.04 as again supported by Robotis. User can use Arduino IDE, and the IDE plug in is maintained and getting better. Maybe also good enough for the higher end as well, as you can also configure it for Servo recovery

    As mentioned RPI hat would be great for non-entry level... We have seen enough people on this forum and others who more or less refuse to learn and use Linux.

    Again I like your RC like receiver, especially since it supports serial output. May have to get one. Bluetooth, yes sort of a pain, plus maybe not the greatest for things like Mech Warfare, but:

    If you have a processor that supports USB, like the linux boxes or you have some Arduino version supporting RPI, then you can get cheap BT adapters (< $10) if needed as some RPI already have BT built in, plus cheap PS3 clones (< $15), but again still need power.

    Again for me, I will probably build another RPI like shield, with power management using some Teensy, although could make an OpenCM version. As you mentioned just need mosfet to control power to servos, could add in the additional things like maybe sound, or see about stacking that one on (I have one that was mentioned in previous thread that has two speakers plus Mic) built in...

    Also for me, will also do some experiments probably with OpenCR board, as Robotis has ROS/ROS2 support setup for these boards (Turtlebot3), and would be interesting to make a ROS2 version PhantomX...

    Again thanks for the ideas, an RC version to me makes a lot of sense.

  6. #6
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    Re: PhatomX with XL430-W250 servos

    Long time since I last posted anything here.. Teensy 4.xx cool. Did you get any movements from this hex Kurt? Looks very interesting to test a hex with these servos. @jwatte do you have any documentation about the RC transmitter/receiver?
    Kåre Halvorsen aka Zenta
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  7. #7

    Re: PhatomX with XL430-W250 servos

    Hi @Zenta,

    Yep long time... I keep meaning to email you.

    I have gotten some movements, need to work on it some more. .

    Took me a little while to go through and assign the servo numbers (they built it with all servos #1 at default baud), so needed to disassemble enough to connect one servo at a time to assign proper IDs, plus changed baud to 1000000, plus zero out delay....

    But then running into issue with the XBee connection that I made for OpenCM9.04 board (at least on that board), It was working on standalone board with OpenCM 485 expansion board setup, so need to see if something wrong with not using it. Like maybe not enough voltage backfeeding from DXL Hub to OpenCM?

    Want to talk to you about some about code bases and the like.

    Still hacking away at Teensy4 stuff (plus 3.6) with the USB support. In particular getting Bluetooth to somewhat work. Currently have it working with some keyboards and Mice. Also it works now for PS3 and PS4 controllers. Currently trying to figure out XBox one.

    Hope things are going well for you!


  8. #8

    Re: PhatomX with XL430-W250 servos

    @jwatte do you have any documentation about the RC transmitter/receiver?
    The receiver outputs this protocol:
    It's ten 16-bit integers with some surrounding framing information.

  9. #9

    Re: PhatomX with XL430-W250 servos

    Thanks again @jwatte - I decided to order one to try out

  10. #10

    Re: PhatomX with XL430-W250 servos

    Quick update: When I ordered the Receiver it said is should arrive sometime between April 3 and 24th... But looked today and it is out for delivery... So should be able to pick it up tomorrow

    So next up setup to use it with this PhantomX.

    Note: I believe the current code is at least partially working to have it walk using the Arbotix Commander.

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