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Thread: USB2AX v3.0a feedback

  1. Lightbulb USB2AX v3.0a feedback


    This thread concerns the USB2AX beta-testers, but input from people who does not have the board in hand is welcome too!
    Since most of the USB2AX tester are Trossen Robotics forum members, and the USB2AX would most likely become a product sold by TR, I hope it's not a problem if I post this here.

    Please have a look here at the USB2AX v3.0a documentation (work in progress!)

    This round of testing is to get feedback on all the possible aspects of the USB2AX, towards the goal of turning it into a tool the community would really be interested in. It would be great even beginner users would have no problem using it, yet it still allowed advanced users to have fun by modifying it to fit their most demanding needs.

    Please comment on anything you can think of, based on your background and what you would be looking for in a small USB to AX/MX-series Dynamixel adapter!

    Some ideas:
    - ease of use,
    - form factor,
    - design,
    - firmware functionalities and performance,
    - hackability,
    - marketability / brand image,
    - manufacturability / DFM,
    - licensing,
    - surety,
    - ...

    An other thread with feedback from some other testers is available here:

    Points already raised:
    - the USB2AX should come with the Dynamixel connector soldered (Tyberius)
    - type of connector to use: could be straight (the one you received) or right angled (the one in the original USB2Dynamixel). PedroR suggested to use a straight connector and to lengthen the board a little bit so that it sits on the PCB properly.
    - have the USB2AX wrapped in heat-shrink tube to protect from misuse and inadvertently frying the unit (PedroR)
    - make it clear the USB2AX does not support 4-pin Dynamixel bus. based on the current design silkscreen, I can see why someone would think that.

    Let's begin!
    Last edited by Xevel; 10-15-2011 at 08:42 PM.
    Personal blog:
    USB2AX documentation:

  2. #2
    Join Date
    Jun 2011
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    Re: USB2AX v3.0a feedback

    Got mine today. I'm of the opinion that right-angle connectors make sense here... And I had a bunch myself so I used one of those.

    My right angle connector has some extra plastic that yours doesn't. These are right up against the atmega, and I wonder if with prolonged usage, the plastic connector might push on the atmega and break solder joints. The solution would be to add like half a mm separation. See pic attached. Browse: Publix Ad Preview and Kroger ad this week on Weekly Circulars.

    Click image for larger version. 

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    Edit: oh, hey just saw the note that you bent pins on a straight connector to get your right angle effect. Well the above is what the real right angle connector does, of course

  3. #3
    Join Date
    Apr 2010
    Rep Power

    Re: USB2AX v3.0a feedback

    Yes a right angle 3 pin seems like a better fit for a direct usb input board. I will try the bending of the straight pins tomorrow on the 3pin bus.

    I was the confused member by the RX silkscreen and hole. But already got confirmation that the USB2AX does not support the RC servos. Which is okay, I just got a little excited that it could be used for RX servos as well.

    Those are my only ides so far. I should probably have more tomorrow after I solder on the bus and plug it in.

    Thanks Xevel for letting me be a tester in this cool pursuit.

  4. #4

    Re: USB2AX v3.0a feedback

    I too mounted a right angle 3 pin connector, and agree that while it fits, it does not look too comfortable.

    Adding the heatshrink is a good idea, but given how well Arduinos and similar survive, not sure if essential. It will also make it a bit difficult to get to the reset/boot pins. Maybe clear heatshrink with a hole similar to the SMPS2DYNAMIXEL.

    For the programming I have a 3 pin male .1 header on a scrap of board with a push button. Two pins are shorted to give the /HWB and the /RST is on the button. I also sent you a code version which allows soft entry into the bootloader.

  5. #5

    Re: USB2AX v3.0a feedback


    It may also be good to build a list of supported software. This will give some head start to users and also enable the building of a testplan for future firmware versions and updates.

    I have just tested with Dynamixel Wizard version under Roboplus version
    Following works OK.

    Dynamixel Firmware Recovery
    Dynamixel Search ( tested at 1Mbps and 57142bps)
    Write Baud rate
    Write Read return Delay
    Write Goal Position
    Read Present Position

    The LED is very bright.

  6. #6

    Re: USB2AX v3.0a feedback

    Just another trivial one !

    When my PC goes into sleep. I think the PC USB goes into suspend, anyways the USB2AX LED goes off.

    When I resume, all works fine, but the LED is now staying off.

    I guess I can fix this, just wanted to get it logged.

  7. #7
    Join Date
    Jun 2011
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    Re: USB2AX v3.0a feedback

    I've never had the LED turn on, and gotten no feedback from the Atmel Flip program. (I presumed it came with some version of the firmware - this hasn't been specified - but obv. testing to see if I could upload firmware)
    -Tested with two computers (Win XP and Win 7). Both notice when I plug in something to the usb port but I don't think
    -It shows up in the Device Manager as LUFA USB-RS232 Adapter, but doesn't have a driver installed.
    -I do have the connector soldered on as above, but I've never yet fried any hardware by overheating due to soldering.

    Are there points on the board that I should check with my multimeter? Is there a driver that ought to be installed? (ought to be auto-installing?)


    P.S. another note, if one were to put a 4 pin right angle connector on, it would hit one of the surface mount devices (aka if you were going to do a 4 pin connector with 3 wires for the GND-TX-RX connection, presumably)

  8. #8

    Re: USB2AX v3.0a feedback

    The USB2AX uses CDC drivers. Windows does have these drivers, but is not bright enough to use them. Linux will install CDC drivers automatically.

    For Windows you need the .inf file to tell it what driver to install. The driver is here:

    To program new firmware, you need to start the bootloader in the USB2AX, this is done with the /HWB, GND, and RST pins. Holding /HWB low at reset will enter the bootloader. The USB2AX will be seen by Windows as an ATmega32u2 device and then can be seen by Flip. I use this below to hold /HWB low and then reset with button beacause I do it quite alot during development.
    Click image for larger version. 

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    Also have sent to Xevel a version of the firmware which can enter the bootloader from software.

    I guess this is your problem, just ask if you need more help.

  9. #9
    Join Date
    Jun 2011
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    Re: USB2AX v3.0a feedback

    Thanks for the pointers! I was able to install the LUFA driver on my desktop (Win 7) (my mind is boggled that I've never used a .inf file to direct the installation of a driver before...), and got the green light. I've been unable to install the driver on my laptop (XP), though.

    Using the Dynamixel Wizard was fruitless, however. I decided to tackle uploading the USB2AX.hex file with FLIP, but with no change in results. (It took me a long while to discover the Atmega32U2 DFU driver was in the FLIP install folder)

    Attached is a pic of my setup. I'm just using a 12V DC supply to the servo power rails, and the dynamixel connectors. (The rest of the board is for TTL<->AX12 with an Axon microcontroller, but I"m not using that here)

    Any ideas?

    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  10. #10

    Re: USB2AX v3.0a feedback

    Your hardware setup should work OK. Is the TTL<-> AX12 logic disconnected, so it does not pull down the signal in the AX bus ?

    How far do you get with Dynamixel Wizard ? I guess you have seen the correct COM port in device manager, and can open to this port in Dynamixel Wizard.

    When you scan servos do you get none found ? What baud rate do you use on AX12 ?

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