In this paper a new approach for an overall system design is presented. It supports object-oriented system modeling for software components in embedded systems in addition to time-discrete and time-continuous modeling concepts. Our approach provides structural and behavioral modeling with frontend tools and simulation/emulation with back-end tools. The UML metamodel is used for storing CASE data in a MOF object repository and XMI (XML Metadata Interchange format) is used to interchange this data with UML-CASEtools. The CASE tool chain we present in this paper supports concurrent engineering including versioning and configuration management. It provides adaptors for the tools MATLAB/Simulink/Stateflow1 and ARTiSAN Real-Time Studio2 as well as an importer/exporter of UML/XMI. Utilizing the Unified Modeling Language notation for an overall system design cycle, the focus of this paper lies on the subsystem coupling of heterogeneous systems and on a new code generation approach.