must I use pd2 also in case of interrupt version? and so given I have to switch a pin that now is used for the keyboard matrix, is that better to use the interrupt version or usart?
the two options would be:
1) int version: pd1 for clock, pd4 for data , pd5 for keyboard row
2) usart version: pd5 for clock, pd2 for data, pd4 for keyboard row
also, thanks for the answers, you are really helping me out!