Abstract—Building highly optimized embedded systems demands hardware/software (HW/SW) co-design. A key challenge in co-design is the design of HW/SW interfaces, which is often a design bottleneck. We propose a novel approach to HW/SW interface design based on the concept of bridge component. Bridge components fill the HW/SW semantic gap by propagating cross the HW/SW boundary and raise the abstraction r designing HW/SW interfaces by abstracting processors, buses, embedded OS, etc. of embedded system platforms. Bridge components are specified in platform-specific Bridge Specification Languages (BSLs) and compiled by the BSL compilers for simulation and deployment. We have applied our approach to two different embedded system platforms. Case studies have shown that bridge components greatly simplify component-based codesign of embedded systems and system simulation speed can be improved three orders of magnitude by simulating bridge components on the transaction level.