> Start
> Repeated Start (that's start when there's already been a start, but
> no stop)
> Send
> Stop
> Set receive
> Acknowledge a received byte
>
> I assume that these are implemented in software, not hardware, though
> *I* think that a start an Ack should be automatic.

They are implemented in hardware in the MSSP.  You only set the appropriate
bit and ACK or NACK is automatically sent.  You want control over this in
software because sometimes you want to NACK a byte instead of ACK it.

> - From the datasheet, ...

So just read the data sheet.  At best you didn't introduce any errors.

There is still no substitute for reading the data sheet.  I strongly
recommend to anyone using the MSSP module to read the entire IIC section,
except that you can skip the multi-master stuff if you are not doing
multi-master.  Otherwise, read it thru entirely.

Of course the tricky parts come from the stuff not mentioned in the data
sheet.  It covers the basic normal cases just fine, but these don't cause
the trouble.  This is why you need to read the whole IIC section very
carefully.  You need to try to understand the implementation so that you can
make educated guesses about what happens when something out of the ordinary
is being done.  Even then you will have to do some experimenting.

For example, what exactly happens when a slave is overrun on a write?  Sure,
an overflow bit gets set, but how exactly do you recover?  What does this do
to the slave state machine?  What implications does this have to the higher
level protocol that you have to design?

This is just one example of what would be useful to include in additional
documentation.  I don't see any value in a document that just reads the data
sheet to you.  At best it doesn't introduce errors.  IIC via the MSSP is not
the kind of thing you want to distill down to "cookbook" level because there
are subtle complexities that will bite you.

Someone else posted a link to a Microchip PDF about IIC.  At least it has
added value because it introduces IIC concepts in small baby steps suitable
for beginners.  However, I flipped thru it quickly and quit after the first
blatant error confounded by an outright wrong example.  Argh!!



*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body