My most beloved topic - the PCF8574 with a HD44780

well... i am fiddeling with that code for more than a week now.. and somehow its nothing hard at all, so i guess that i can learn more from watching how a working version was done than to keep trying to figure out what i have done wrong..
I guess t is something quite simple, my bet is on the Nibble stuff, yet i cant figure it out and so.. well, i would like to see how it is done ;0)