John Fremlin's blog: Activating the Dynamixel MX-28T actuator

Posted 2014-07-29 14:59:00 GMT

In our quest to make a robotic hand, we procured an awesome actuator, the Dynamixel MX-28T.

This marvelous device can not only spin but also go to a precise goal position, and hold it against varying torque, using its mighty 72MHz processor to adjust as necessary.

We wanted to use the usb2ax to control it. To our surprise this is actually impossible out of the box, as oddly enough, the MX 28T is programmed to start off listening at 57142.9 baud and the usb2ax can only use 1MHz. This is all the more bizarre because the base clock serial clock of the MX 28T is 1MHz or 2MHz depending how you think about it.

I guess we could have tried to do something cool with a serial port as this is quite close to 57600, but we didn't and we got another controller to program the poor MX-28T which lives on a nice bus to change register 4 to value 1 so we could talk to it.

Then everything was hunky dory. The servo is surprisingly strong!

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