Lpc2000

--- In lpc2000@yahoogroups.com, "Sutton Mehaffey" <sutton@...> wrote:
>
> I haven't totally gotten my I2C (LPC2148) to work with my RAMTRON
> serial RAM yet.  All the status' look good on both writing and reading
> to RAM, but still get 0xA1 after I write a 0x77.  
> 
> However, I noticed that even if I have no power on my RAM and no SDA
> and SCK lines connected, all the status' are exactly the same and the
> data is still 0xA1.  It seems as though if the RAM weren't responding
> at all, you shouldn't get valid codes.  And, I have my ACKs turned on!
>  Any ideas?
> 
> Sutton
>

Two things:  First, I assume your I2C code is from the Philips samples
in the Files section, right?  I would certainly start with this before
branching off to bigger and better things.

Second, I haven't had much success getting I2C to work without a logic
analyzer.  I have a couple of them but even the cheap setup from
KronosRobotics will work.  See
http://www.kronosrobotics.com/Projects/KRAnalyzer.shtml

In one of my magazines I saw a circuit to detect the start condition
and use that to trigger a scope.  It also implemented some other
trigger conditions.  Unfortunately, I can't find the magazine.  I was
thinking about stuffing the circuit into a CPLD.

I don't know anything about the 2148 but I did use I2C on the 2106 and
it worked fine.  I grabbed the code from someplace - I don't even
remember where.  However, I was just talking to Microchip Port
Extenders and an LCD display.

Richard