This paper addresses the design of nowadays embedded hardware and software systems. We propose an interactive tool enabling designers: to easily describe and configure system solutions at the functional and the architectural levels, to interactively define properties for all internal components, to incrementally generate executable code programs for both hardware and software components.The basis of our approach is the MCSE methodology which specifies the description model and the method designers can follow to develop Hw/Sw solutions. The graphical model useful for system-level description includes the functional structure, behaviors of components, the physical architecture, the functional architecture mapping after Hw/Sw partitioning. Our model also includes the concept of attribute to specify standard and user-defined properties for all components. These attributes are interactively edited and they directly drive a set of code generators, each one focussing a specific target (C with WxWorks, synthesizable VHDL, Hw/Sw interface, C++).