Lpc2000

I come from the other side of the problem.  All of my background is in
hardware design.  I struggle with things like Linux and the GNU
toolchain but datasheets and timing specs are a cake walk.

But, we're all having fun or we wouldn't be here!

Richard



--- In lpc2000@yahoogroups.com, Tom Walsh <tom@...> wrote:
>
> Sutton Mehaffey wrote:
> 
> >Thanks Richard.
> >
> >I think I discovered 99% of the problem.  Apparently, I was shipped
> >samples of the Serial RAM FM24C256 chip that were true 5V parts and I
> >asked for 3.3V.  Makes it a little difficult to get the chip to work
> >:)  But, I will also change my pullups when I get the correct chip in.
> > They are too high.  
> >
> >I've been a software designer for many years and I am trying to learn
> >more about the hardware side and do some of the design myself.  I
> >found I don't learn how the hardware works as well if I have someone
> >else do all the hardware design.  So, sometimes I miss some things in
> >the datasheet that are very important (4.7K pullups instead of 10K). 
> >It's fun to learn, though.
> >
> >  
> >
> 
> That's how we all did it, you can learn all you want in schools, but 
> until you get into the real world ...
> 
> I've learned a lot by looking at other's designs, heh, I do not
"know it 
> all" and it is is fun to learn new stuff!
> 
> Enjoy,
> 
> TomW
> 
> >Sutton
> >
> >
> >
> >--- In lpc2000@yahoogroups.com, "rtstofer" <rstofer@> wrote:
> >  
> >
> >>--- In lpc2000@yahoogroups.com, "Sutton Mehaffey" <sutton@> wrote:
> >>    
> >>
> >>>Charles,
> >>>
> >>>Using 10K pullups.
> >>>
> >>>      
> >>>
> >>10k isn't a pull-up when applied to I2C.  The absolute maximum that
> >>might work on a good day is about 4.7k and a more realistic value is
> >>    
> >>
> >2.2k.
> >  
> >
> >>You never provided a link to the RAM device (that I recall) but in
> >>looking at the FM24CL64, they recommend a 1.1k pull-up.  The reason it
> >>is so small is the lower VDD.  Normally, at 5V VDD the pull-up can go
> >>as low as 2k, maybe 1.8k.  At 3.3V the resistor would be somewhat
> >>    
> >>
> >smaller.
> >  
> >
> >>But, again, I don't know which device you are using.
> >>
> >>Richard
> >>
> >>    
> >>
> >
> >
> >
> >
> >
> >
> > 
> >Yahoo! Groups Links
> >
> >
> >
> > 
> >
> >
> >
> >
> >
> >  
> >
> 
> 
> -- 
> Tom Walsh - WN3L - Embedded Systems Consultant
> http://openhardware.net, http://cyberiansoftware.com
> "Windows? No thanks, I have work to do..."
> ----------------------------------------------------
>