Hi erik,
I use 80C552 with I2C hardware. But the problem is the same. The controller always jumps to an interrupt-routine and gives you a code for the last I2C-state. But the problem still is the same. You get a state-code called "arbitration lost" because your controller wants to write a "1" one the bus and another "0" sdestroyes this "1".
And if you want to write more then 2 bytes into the PCF8582, you must wait for 60ms between each 2 bytes. If you just wait, a little and write again, it offen happens the same. Am I the first with that problem ? Or where is my "understanding-problem"? (excuse my "german-english")
nice day
Rolf