The book Serial Pic'n goes through I2C thoroughly(115 pages just for iic),
including master and slave modes, with code.  I just got my copy, and know I
will be referencing it quite a bit as I go along.

http://www.amazon.com/exec/obidos/ASIN/0965416224/adamdaviscollect
(helps me support my PIC website)

It is well worth the $50 it costs at Amazon.

If you just want the code, Square One has it here:
http://sq-1.com/srccode.html

The routines you'll be interested in are:

MASTER:
Use EEPROM - ORANGE1.ASM
Use A/D - ORANGE2.ASM
Use A/D & EEPROM - ORANGE3.ASM
ORANGE4.ASM and ORANGE5.ASM go with the next two SLAVE programs

SLAVE:
FAWN1.ASM
With ACK polling - FAWN2.ASM

I hope this helps!

-Adam

Greg Hartung wrote:
>
>    Well, there's certainly more questions about I2C than answers.
> Since no one seems to know how to do this, I will continue informing the
> list of my progress.  I finally got some DS275's, so I substitued one
> for the MAX232 just to make sure those charge pumps weren't screwing
> with me again.  No improvement, however, other than 5 fewer caps on my
> board :-)
>    So I decided I'd done enough homework and called Microchip.  At first
> they said, oh, yeah, sure, you just need PICDEM2.ZIP.  Well, it is
> technically an example of I2C, but it's mostly bit banging; it certainly
> isn't code for master mode on the 877, tho.  So then they admitted they
> are working on an AN and will try to get the code to me.  uhu, sure...
>
> > It's a bad day when I'm replying to my own messages...
> >
> >    I tried de-coupling caps on the EEPROM.  I put huge 40ms delays after every I2C
> > bus access.  And I put a scope on the SDA and SCL.  SCL had a rock solid pulse at
> > 385kHz, just like I calculated.  Big grin on that one.  And SDA had 1's and 0's all
> > over the place.  I also tried 1K pullups instead of 2K, and 33pf caps on the bus
> > lines, but I still can't get anything out that looks like what I put in.
> >
> >
> > Greg Hartung wrote:
> >
> > >    No problem, Mike, any input is welcome.
> > >    I found one eroneous line in the code.  I moved the clrf SSPSTAT that was
> > > after the switch to Bank 0 to before the switch because SSPSTAT in bank 1.
> > > Will I ever learn?
> > >     I also tried a value of 49 for a clock of 100kHz.  And I also tried
> > > commenting out the SSPCON2 inits.  And I even tried changing the slew rate for
> > > the 100kHz test.  The output was still the same rotated pattern of grouped 1's
> > > no matter what I did.  The 100kHz did slow the output down quite a bit, which
> > > was encouraging.
> > >    Pleeeeeeease someone help me.
> > >    I am foolishly thinking of putting the scope on it, but I dunno what to look
> > > for.  Those timing charts in the datasheet hurt my head.
> > >    Does anybody know how I might read the I2C with some other device to try and
> > > narrow down if I'm having read or write problems?
> > >    I also noticed the original author had a stop bit before the second start
> > > bit in the i2c_read proc, but the 24lc256 datasheet does not indicate that it
> > > should be there.
> > >    I have 2k pullups and no caps on SCL and SDA.  Should I try decoupling caps
> > > on power again?  (Can't believe I just thought of that...  not the brightest
> > > lad sometimes...)
> >