For the communication of hardware and software via memory mapped I/O e.g. in an embedded system, it is necessary to specify the communication registers in every detail. Since this work usually needs to be done for hardware and software independently, this work is time consuming, difficult, and error prone. This paper presents an approach to model hw/sw interfaces in an XML-based[8] interface description language called ComiX. We believe that an abstract and target language independent modelling technique based on ComiX can improve designers productivity and the systems reliability through reuse and automatically generated target code. Furthermore this paper describes a tool architecture to generate software device drivers and hardware I/O components automatically from a ComiX specification.