Mike Mansheim <PICLIST@MITVMA.MIT.EDU> wrote:

> Why is eight the limit for a pair of I2C lines?

    Mike:

    It's not an I2C limit, it's a 24-series EEPROM limit; each EEPROM
    has only 3 address lines (A0, A1, and A2) which can be tied high
    or low to give the chip its own address.

> >   Actually, Mike, it takes a MAXIMUM of 10 ms from the end of
> >   your "write" command until the write is actually complete.
>
> I know it is a maximum spec - however, I typically just make sure
> enough time has elapsed before accessing the eeprom again - and in
> that case, I use the 10ms number.  Again, I can only comment on
> the 24LC01, but it does not have a convenient "I'm done writing"
> flag. You need to keep sending the eeprom's address (assigned by
> Phillips!) until an ack is received to know when it is ready for
> you.

    Correct, but since the EEPROMs generally complete their write
    cycles in much less than 10 ms, it pays to do the address/ack
    thing if you need speed.

    Also... The most efficient way to do it is to check the busy
    flag (with that address/ack protocol) just BEFORE you access the
    EEPROM, rather than just after you perform a write.

    -Andy


=== Andrew Warren - fastfwd@ix.netcom.com
=== Fast Forward Engineering - San Diego, California
=== http://www.geocities.com/SiliconValley/2499