interfacing uart ttl full duplex 2 dynamixel half duplex

[FabinovX]

Hello.
surfing at robotic's support i saw that :
http://support.robotis.com/en/product/dynamixel/dxl_ax_main.htm
if it works from cm5 uart ttl to dynamixel, what about in the other way..
that's ok, i'm a newbie in everything, but i would like to know if such a scheme would be ok to connect ttl uart sensor (as chR6D or VRbot Voice Recognition Module using 5v regulator) to cm5 or cm 510 dynamixel bus ?

[billyzelsnack]

Not without additional circuitry. Devices on the bus need to adhere to a very specific protocol and a sensor would need to encode its data into the protocol.

[FabinovX]

OK thank you for your answer.

But, is dynamixel bus using a private robotis protocol or is it using a standard protocol which can be translate with a standard chip as a max or something else like that ?
is there a doc where is that protocol is discribed or maybe a source code of controler firmware.
it may help a lot to do such an interface and programming the interfacing chip (an atmel or pic is suppose).

i apology for my quite bad written/spoken english.

[Stephane]

Hello,

I think FabinovX is aware of the additionnal circuitery because the link he mentionned describe the circuitery required to interface a "standard" uart TTL bus to a dynamixel bus (btw, you can find this information in the dynamixel manual too). This circuitery is used in interface board designed by John Hyland (sorry if I mispell your name, I write it out of memory) and all; you can find posts about this interface board in the forum (quickest way to find it is to go through the wiki), it is a very interesting source of information if you want to build such interface.

In the dynamixel manual (link can be found in the wiki), you will also find a description of the protocol, plus the registers of an AX-12+ servo. I don't know if a documentation about the robotis sensor exists as well (I am not interested in sensor yet).

But since you want to interface your sensor with the CM5, the biggest issue for me is wether your CM5 will be able to access and use properly your custom sensor.... probably not if you don't develop your own firmware for it.

Cheers,

Stéphane

[billyzelsnack]

A micro-controller is "circuitry?" haha. You're right. I should of said "mico-controller" to be more specific.

[FabinovX]

well my lack of vocabulary leads to missundertanding.
the additional circuitry (as you say) is described in the link i gave.
there will be some voltage regulator to add and soft to writte too.
but, i was just asking if it was the only thing needed to build an interface.

nobody already tried to do such an interface by now ?

i though it will need some µcontroler to manage half duplex timing and buffers.
is that right ?

cheers

[billyzelsnack]

Lots of people have made interfaces. Here is a tutorial using an Arduino..

http://forums.trossenrobotics.com/tutorials/how-to-diy-128/controlling-ax-12-servos-3275/

Robotis also sells one called a USB2DYNAMIXEL.