PDA

View Full Version : Arduino with MX-28



orion
06-07-2012, 03:36 PM
Hey all,

I'm starting a project based around the arduino micro controller and i'd like to try and use it to control an MX-28. I found a bit of info out there on connecting the AX-12 to the arduino and I was wondering if it would be the same wiring for TTL on the mx28. this is the main site i found http://tiny.cc/a6ujfw (shortened the url cause its a translated page). I have the servo connected through a 74ls241n buffer and am running a basic write code using the library he provided, but im not getting any results. the servo gives the single blink power confirmation so its powered, but theres definitely something im missing here... i also checked the table for the mx28 and it seems to be the same as the ax12 so all of the commands called by the program he wrote should work fine. i sent him a message as well but i wanted to post here to see if there was anything you all could recommend.

thanks!

sotkoon
09-21-2012, 12:01 AM
Hi Orion,

I was referring to the Pablo Gindel's method to run my AX-12/18 previously. I just managed to port it over to MX-28, facing some small problem. https://robosavvy.com/forum/viewtopic.php?p=34958

I think your problem might be due to the incorrect baudrate during initialization. You can try to set the baudrate to 57600, as the default baudrate and id for a new mx-28 is 57600 and 1 respectively. http://www.crustcrawler.com/motors/MX-28/docs/DYNAMIXEL%20MX28T.pdf

Hope it helps.

CK

jwatte
09-21-2012, 11:29 AM
Also, the AX series uses "TTL" level signalling, but the bigger servos use RS-485. (or are you using the "T" version?)
You may need a translator/buffer chip.
These are a very standard part -- all manufacturers use the same PDIP-8 pinout. The cheapest one on Digikey is $2:
http://www.digikey.com/product-detail/en/SN65HVD485EP/296-17498-5-ND/698092

N (http://www.digikey.com/product-detail/en/SN65HVD485EP/296-17498-5-ND/698092)ote that you probably want to use a socket, because this chip also serves as a convenient fuse, protecting the rest of the board against "accidental" voltages on the communications wires ;-) This, plus the better resistance to interference, is a good reason to use RS-485 instead of TTL.

Gertlex
09-21-2012, 12:06 PM
Also, the AX series uses "TTL" level signalling, but the bigger servos use RS-485. (or are you using the "T" version?)

Going by the timing of the original post, he's using a 'regular' MX28, which uses TTL. The T/R flavors were released a while later...