Dear PIClisters, In my current project, I need to connect a MPU powered by 3V to a DSP powered by 5V. The probelm lies in connecting the bi-directional DATA line in two different logic systems. In this case, I have selected two open-drain ports to act as data pins, but I haven't yet found the simplest way to convert the levels properly. Would you be so kind to show me your solutions? Thanks in advance! -- __________________________________________________ :-)) TEL: 86-756-2236157 2115540 FAX: 2115541 :-)) Email: zhuxh@cheerful.com ICQ#:7037093 ==================================================