AVR-Chat

Hello, Jay -

First off, it sounds like you are thinking of an entirely
peer to peer system. I've worked with such systems and they
can be pretty difficult. If the "network" is shared by all
(as opposed to isolated point to point links between each
pair of controllers), you have problems with "collisions"
as one tries to send a message when another one is also
trying to do the same thing.

IF you can arrange it in a master/slave fashion such that
the master polls each slave about its state, then sends
that information to the appropriate destination, it would
work a lot smoother. This could be done with SPI, or TWI,
or even async serial UARTs.

Yes, you can power 5V regulators from the output of 12V
regulators. Thats not much of a problem. Watch out for
power dissipation, however. If you are delivering 100ma
from a 5V regulator with 12V input, that 5V regulator is
dissipating (12V-5V)*(0.1A) = 0.7W. That would require some
heat sinking! You also have to consider that you are adding
to the current delivered by the 12V reguloator and, thus,
ITS power dissipation.

Hope this helps
Jim

On Thu, 29 Jun 2006 09:11:35 -0700
 "Jay Dagenais" <jaydag71@hotmail.com> wrote:
>  Hi again, I am seeking some info regarding linking
> multiple AVR modules together. In the design, there would
> be say a few Uc' units, each having their respective
> control circuits and all that stuff. I need to find out
> how to get each unit to be able monitor and communicate
> with each other module, and change states based upon the
> results of polling eachothers various inputs. 
>  
>  Eg. three modules each having a uC, stepper motor
> control circuitry and input sensors, such as push-buttons
> and IR rangers. I am trying to use the tiny45 for each
> uC, but am not sure if I am going to be able to do all
> needed functions using such small pin counts, but another
> problem...Anyways, say I wanted to monitor the states of
> each modules input sensors and drive each stepper in
> different duty cycles based upon the results of the
> inputs. The design is meant to be modular, and able to
> accept in theory as many or as few modules as needed in
> specific app. So they have to be able to work together
> and seperatly based on what is desired without much
> modification to hardware.
>  
>  Questions,1- if I need around four pins to drive the
> stepper on each uC, say one for the input sensors, and ?
> for uC to uC communication, am I going to have to use a
> different device, or can this be done using inturrupts or
> some other fashion?
>  2- minimally how few pins can I get away with using for
> the uC to uC communications? for programming how would I
> approach the interface? ISP for each or able to program
> each device at same times, or both?
>  
>  Lastly, if I need 12V and 5V regulators, can I run the 5
> directly from the output of the 12, and have no problems
> with noise or nasties like that using the outputs to
> drive (5 for digital and 12 for analog drive??).
>  
>  Well, thats it for now, and thanks in advance for any
> help with these! jaydag71- sunny Vic BC.
>
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