The problem of designing mixed hardware/software systems has received a significant interest in recent years due to increasing system complexities. One task in hard-ware/ software codesign is the verification of heterogeneous designs. This is achieved by cosimulation. This paper describes a hardware/software cosimulation environment for embedded systems based on digital signal processors and FPGAs. Due to the heterogeneous nature of an embedded system we are using an multi-language approach for the simulation of the entire system. We define a generic, tool independent and open interface concept. Using this cosimulation interface an efficient verification of the design is possible.