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Thread: AX12A Baud Rate

  1. Question AX12A Baud Rate

    Hi all, I seem to have set the baud rate of my ax12a's to the wrong value.
    Initailly i set them to 207 (9600 baud rate) then accidently set the baud register to 0.
    I saw the other post relating to this but could not make much sense of it.
    It seems now that any commands (I have tried SetPosition and ax12setregister) in the bioloid library (ax12.h and ax12.c) dont work anymore so I dont think i have a way to comunicate to servos anymore.
    Could someone please advise me on how to reset them as i do not have a usb2dynamixel and i am from south africa and am not able to find one here and I am in urgent need of being able to control my servos again as it is for my final year project.
    I am using an arduino mega 2560 and tx1 and rx1 for the servos.
    Thanks alot

  2. #2

    Re: AX12A Baud Rate

    You need to either buy a USB2Dynamixel, or some other device that is capable of recovering the servo firmware. I think boards like the CM-900 can do it, too, but I haven't done it myself so I could be wrong.

  3. Re: AX12A Baud Rate

    Quote Originally Posted by jwatte View Post
    You need to either buy a USB2Dynamixel, or some other device that is capable of recovering the servo firmware. I think boards like the CM-900 can do it, too, but I haven't done it myself so I could be wrong.
    Thanks alot for your help
    Is there no other way without ordering one of these devices?

  4. #4

    Re: AX12A Baud Rate

    I guess you could build one of these devices yourself? That's kind-of a lot of work, though, as the firmware isn't open and you have to reverse engineer it yourself (as the USB2AX did.)

  5. #5
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    Re: AX12A Baud Rate

    Quote Originally Posted by DVS View Post
    Thanks alot for your help
    Is there no other way without ordering one of these devices?
    If you set the baud rate register value to 0, then your baud rate is 2000000.0 bps based on how they calculate it.
    Speed(BPS) = 2000000/(Data+1)
    http://support.robotis.com/en/product/dynamixel/ax_series/dxl_ax_actuator.htm#Actuator_Address_04

    I've never set my baud rate to 0 before, but you might want to try communicating with it at 1000000 bps and see if you can. It may ignore a baud value of 0 and set it to 1.

  6. Re: AX12A Baud Rate

    [QUOTE=jwatte;59647]I guess you could build one of these devices yourself? That's kind-of a lot of work, though, as the firmware isn't open and you have to reverse engineer it yourself (as the USB2AX did.)[/QUOTE

    There is no product of reverse engineering in the USB2AX. Using it to reset a servo or to talk to the servos in any other way is (most of the time) just using it in passthrough mode (in this mode it makes sure things that come from the bus are transmitted to the host, and things coming from the host are transmitted to the bus, nothing else).
    It is possible to make a similar device from an arduino leonardo as long as you make sur you do things properly (risks of damaging the board ). You have to connect TX and RX together with small resistors, like between 47 and 100(or no resistor at all but it's risky). Then flash it with the USB2AX code recompiled for your MCU. Some tweaking might be necessary. PM me if needed.

    F#[email protected]%ing Android phone does not like this forum. ><
    Last edited by Xevel; 08-18-2013 at 12:47 PM.
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