This paper presents a codesign approach which incorporates communication protocol selection as a design parameter within hardware/software partitioning. The presented approach takes into account data transfer rates depending on communication protocol types and configurations, and different operating frequencies of system components, i.e. CPUs, ASICs, and busses. It also takes into account the timing and area influences of drivers and driver calls needed to perform the communication. The approach is illustrated by a number of design space exploration experiments which use models of the PCI and USB communication protocols.