Matthew,

At the same site I pointed to in response to your previous post (on UART timing), look for the file "i2cbitst.zip". You may find it useful.

Why do you say that timing with NOP's is not accurate at all? Execution of a NOP always takes 12 clockcycles on a "standard" 8051 and is, therefore, just as accurate as your clockfrequency. For implementing delays of a couple of µsec. (as needed in I2C timing) the NOP is a good choice. Of course you have to be very careful when porting your code to another circuit which uses a different clockfrequency...

Regards,
Rob.