AVR-Chat

No, the internal pullups are just a little too large. The issue is speed. The clock and data rise times are entirely set by line capacitance and resistor value. 

If you are willing to run slower than maximum speed, then you probably could manage with the internal pullups.

Jim Wagner
Oregon Research Electronics

On Oct 23, 2011, at 3:24 PM, jstockma wrote:

> Thanks, woulf the internal pulls ups be sufficient? My design includes external pull up resistors.
> John Stockman
> 
> --- In AVR-Chat@yahoogroups.com, "tim gilbert" <tim@...> wrote:
> >
> > You probably don't need to run off the same power supply but, if by 'two wire' you mean I2C-like, then you do need the same ground (and don't forget the pull up resistors).
> > 
> > There's no reason this won't work on a breadboard using DIP components. Been there done that (probably before you were even born.)
> > 
> > Of course, I would ask why you're doing it this way. I've found that good old RS232 is a lot easier for most things but that depends on your application.
> > 
> > 
> > Regards,
> > 
> > 
> > Tim Gilbert
> > JEM Innovation Inc.
> > 303-926-9053 (office)
> > 303-437-4342 (cell)
> > www.jeminnovation.com
> > www.pdksolutions.com
> > 
> > 
> > ----- Original Message ----- 
> > From: jstockma 
> > To: AVR-Chat@yahoogroups.com 
> > Sent: Friday, October 21, 2011 6:31 PM
> > Subject: [AVR-Chat] Basic question about breadboards
> > 
> > 
> > 
> > I am a AVR hobbyist and I am currently working on a project to design and program a two wire interface between to Mega AVRs in which one would send instructions to the second directing certain tasks. I have the software side of it well underway but I am having doubts about the hardware part of it. I have determined that I must power each chip from the same power source (in this case a voltage regulator) and that I must connect the two wire busses to a common ground. What I am concerned with is my basic choice to implement this on a breadboard. The busses would be the side rails. I am seeing conflicting opinions about breadboards and their suitability. I would be interested in more views on this from the group. Ultimately I can go with a soldered solution, but I would like to do the prototypes on a breadboard if possible, at least until I get it up and running. I have no EE or EE Computer science training. Thanks, 
> > 
> > 
> > 
> > 
> > 
> > [Non-text portions of this message have been removed]
> >
> 
> 



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