Modern complex system design demands modeling on a high level of abstraction together with the system environment components. Such model enables mission level system simulation in the context of its operational conditions. Mission level design using hardware description language AleC++ is presented in this paper. It provides mission and system level verification of a mixed-signal system-on-chip. After validation at mission and system level, this language enables designers to replace some of the components with implementation level models to test and validate the system implementation at mission level. Also, the language provides modeling capabilities that give the designer an opportunity to analyze the influence of low-level technological and environmental parameters to the complete system behavior. In this way a uniform design framework is achieved from mission/system down to implementation level. The application of the language both for mission/system and implementation level modeling is illustrated by an example of the electronic compass.