undocumented AX-12 instructions

[taiowa]

Have you noticed there are few instructions in the C sample code which are not mentioned in the AX-12 manual?

The instruction are DIGITAL_RESET, SYSTEM_READ, SYSTEM_WRITE and SYNC_REG_WRITE.

Does anyone have more information about these commands? SYNC_REG_WRITE seems obvious.
SYSTEM_READ and SYSTEM_WRITE may have something to do with updating AX-12 firmware.
I have no idea what DIGITAL_RESET might be.

Has anyone used these instructions and any idea why they have been left out of the manual?

[StuartL]

Have you made any further progress on these instructions?

Might be interesting to do a system read of a dynamixel and see if you can get the code. If so can you then write a new version...

If so I'd be in heaven. I'm currently emulating torque control on the CM5. Being able to do that on the dynamixel would be superb...

[Dewey]

Stuart

What do you mean by emulating torque control on the CM5?

Below are my revamed CM5_Header.h and CM5_Primatives.c they use
some of the 'instructions' Taiowa talks about. So what are the extra facilities you/we want?

http://robosavvy.com/Builders/Dewey/BuildingBlocks.zip

Dewey

[StuartL]

One of the things I'm trying to do at the moment is get a servo to attempt to hold a specific torque rather than position. It's a dangerous game to play but it does mean I can dynamically balance on both legs because the servos self correct (i.e. lean) if the floor moves.

For example:

I work out that if the humanoid leans back ever so slightly the ankle servos are stressed to torque x. I then try to keep the servos at this torque setting by fiddling with their position.

Obviously trying to keep the servos at zero torque is ideal for some joints but it doesn't work for others (e.g. knees, ankles).

It's still very much WIP.

[StuartL]

I just noticed (while answering another topic) that the BCP editor has an AX update menu item. I'm at work so couldn't try it out for real but it tries to connect to the CM5. I wonder if it uses those hidden SYSTEM_READ and SYSTEM_WRITE commands to update the firmware of the AX. If so then we may have a way of downloading and modifying the AX firmware. Anyone up for massively parallel robot processing? Or just changing the bus architecture...

[limor]

The issue of reprogramming the AX12 servo has been raised here in the past. I think recalling that someone looked into the AX12 firmware file and it was encoded in some why to make it not trivial to just take a hex file and dump it onto the AX12 servo.

I'm all for replacing the AX12 code with something more useful for closed-loop control. take some ideas from openservo.org.
speed control, real current sensing, faster comms protocol etc. etc.