Keith Howell said:

> Beware!
>
> AN554 and AN578 are only approximations to I2C.
>
> At the bit level, the I2C spec says that an I2C slave
> holds SCL low to 'wait-state' the master.
>
> Looking closely at AN578, you see that the code
> interprets this as a bus error.

Bleugh. That's really bad. I just browsed over that code, never
realising - thanks for pointing this out. I learnt about I2C from
the excellent I2C faq at:

http://www.ping.be/~ping0751/i2c/i2c.htm

There's lots of other i2c stuff there too including the "ICee" drivers
which create an I2C bus on the parallel port of your PC. Cool.

Conor.