On Mon, Sep 28, 1998 at 02:44:11PM +0200, Manuel Bouyer wrote:
> Actually, NetBSD has a sys/dev/i2c with is used by the thunderlan driver
> (if_tl). Maybe you could have a look here too ?
> When I wrote this I tried to do something as portable as possible, but
> I didn't have much docs on the i2c bus.

Get a datasheet of any I2C memory/RTC/other chip and you get the timing
diagrams etc.  For example, Microchip has I2C EEPROM chips and Dallas
has the DS1307 RTC chip which uses I2C.

Some memory chips use two bytes for address and R/W command, some chips
use three bytes (because of a larger address space).  Some chips support
only the slower I2C bus (100 kHz clock, I think) while the newer chips
support the faster speeds (400 kHz (and over?)) as well.

  -jm