Use the interrupts. I coded the I2C driver you say in my loader for the serial EEPROM in less than 4 hours. I took the Cygnal App Note which shows code in C51 and converted it 1::1 to assembler and then stripped out all the parts not pertaining to slave mode. It literally worked the first time I ran it.

Michael Karas

(Some times there is a need to quit a track that you think should work and try something something different. The problem with working on the edge of the data sheet and the available APP notes is that VERY often you think you have it working OK after DAYs and DAYS of messing around...only to find that during final validation or early field trials of the software strange things start to crop up. I just had that happen to me with the Philips I2C PCF8563 RTC chip where my first read/write scheme worked great until the test people had at it and we discovered that the chip has some strange "undocumented" behaviours when its I2C bus is used in a certain way with bit banging and then a long interrupt comes along and makes a 270 uSec hole in the I2C sequence to the chip!!. It was re-design time last weekend....ARGH).

Michael Karas