Saturday, May 5, 2012

BeagleBone Dynamixel AX12 Interface - Part 2


I have made some progress interfacing the Dynamixel AX-12 servo with the Beaglebone.

In this video I have breadboarded a sparkfun logic level converter to convert the Beaglebone's 3.3v UART logic to the Dynamixel's 5v logic and a Tri state bus buffer to convert the Beaglebone's UART signals to half duplex.

I have run into one snag however...
It seems that the Beaglebone's UART are only able to properly work up to 115.2k baudrate by default. If anyone knows how to adjust the maximum baudrate of the Beaglebone's UART to 1M or even 3M baud please comment!


  1. As I posted on youtube:
    Me and some friends wanted to use the beaglebone to control dynamixels directly by the uart...and... I'm sorry but it's not possible to control it at 1mbps. In the datasheet of the AM3359 processor (the one on the beagleboard) you can find in the page 3641 the table of available speeds... You can find the speed 921600, then 1843200... there are no values in the over sampling + divisor to achieve 1mbps. I'm sorry mate! The raspberry pi can't either!

    Link of the datasheet:

    Max uart speed on raspberry pi: 480kbps

    1. It is possible to control dynamixels from a Beaglebone UART at 1MBPS. See my video:

  2. Hi, Great work on this. Do you have a schematic of how you wired up the logic level converter and tristate buffer? Also, have you considered using the PRUs (programmable real time units) on the Beaglebone to handle the serial communication? It looks like they perform in a much more flexible manner as far as speed configuration goes. Thanks!