Lpc2000

That is a pretty ambitious speed for an untried hardware and software
combination! It may be prudent to drop the speed an order of magnitude
temporarily for debugging? You can estimate the maximum speed of your
I2C bus if you know the pullup resistor value AND the bus capacitance.
The pulse rise time is going to be determined by the product of those
two values, so unless you know them you will need to determine the
maximum speed experimentaly by starting slow and working up. The pulse
fall time will be determined by the 2148's open drain driver's current
capacity, but that is much less likely to be the problem IMHO.

--Dave


--- In lpc2000@yahoogroups.com, "Sutton Mehaffey" <sutton@...> wrote:
>
> 120kB
> 
> "What bit rate are you running the I2C bus at?"
> 
> 
> 
> 
> 
> --- In lpc2000@yahoogroups.com, "derbaier" <dershu@> wrote:
> >
> > --- In lpc2000@yahoogroups.com, "Sutton Mehaffey" <sutton@> wrote:
> > >
> > > Yes.  I'm using the Embedded Artists 2148 Demo board, in which the
> > > schematic shows pullups.  I'm connecting a RAM chip via their
> > > accessory prototype board, which has direct connections to the I2C
> bus.
> > > 
> > > Sutton
> > > 
> > > 
> > What bit rate are you running the I2C bus at?
> > The open drain I2C bus speed capability depends on the size of the
> > pull up resistors on the bus, since they determine the rise time with
> > the bus capacitance. If you are trying to go faster than the bus
> > resistors can handle, you will encounter bus errors. To debug your
> > driver logic it would probably be helpful to run the bus at a slow
> > speed until you are more sure there are no software errors.
> > 
> > -- Dave
> >
>