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Multi Axis Bus topology

Posted by mango_make 
Multi Axis Bus topology
January 21, 2011 01:01PM
Hi ,

I have been gathering some thoughts on a plan for a RepStrap derivative here http://reprap.org/wiki/Dynamically_expandable_Bus_Driven_Approach.

Just wondered if anybody else was interested. I have a lot of details to add - especially regarding the electronics implementation, but for now that page should at least give some idea of what I am intending to do.

To cut a potentially long story short - I am aiming to make the design modular (including the electronics) so that as and when I have time to add more to the mechanical side of it I can simply add a new Axis and extend the controllers firmware - without having to start from scratch with a whole new set of electronics. At the same time this means the electronics can start relatively simple and be extended as and when required.

Edited 1 time(s). Last edit at 01/21/2011 02:00PM by mango_make.
Re: Multi Axis Bus topology
January 22, 2011 06:48AM
In other words, i understand that you want to use a stepper ic /w spi like a3985?

or else im not sure what would it mean, coz the mb pins could be enough for multi x [ste/dir/en even reset] for more than 3-4 axis, like hydra-mmm used like 7 or so i think.

that could require a more advanced central mcu, so i would check if casianho had any success with porting firmware to his arm; on the overall this could make quite some advancement;

or the plan is to use a linear stepper with just an mcu and external fets like the linear ones, unipolar even? like linistepper up to 1A? maybe not so good as first variant but simpler, and i think it has been done quite some time ago;

Edited 2 time(s). Last edit at 01/22/2011 07:19AM by NoobMan.
Re: Multi Axis Bus topology
January 22, 2011 10:12AM
Yes I think the Alegro A3985 along with the Atmega48P would make for a very compact and cheap Axis controller. I have used the Atmega48p device along with a DRV8801 to make some small PCB to go in locomotives for model railways so am familiar with it.

The UART can operate at upto 1 mega baud which I hope should be sufficient to keep the serially transmitted commands from introducing too much of a bottleneck in the system when performing complex task such as curves.
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