I do not have much experience in OO, but I use it in software only. I gues it can be usefull in hardware design, when more then 1 uC is used. But it becomes software problem - in hardware level, you only need conectors to fit ;) And as you have allready said, almost all of us, use OO, but don't think about that, and dont call it so! And even more, usualy, OO apears only in coments of the code - you have to put sence, that all functions and variables belong to one object, and wich of them are public or privat. Am I wrong?