The scientific foundations of embedded system development associate two disciplines that have largely grown on their own: computer science and electrical engineering. This superposition of two domains with little common ground raises a number of industrial issues in team work organisation, sound progress tracking, and cooperation between these different skills and cultures. In this paper we introduce HOE², an integrated MDE method for embedded system development that is organised around a set of limited yet powerful artefacts. We describe how HOE² can address the issues faced during development of mixed HW/SW systems and present the first version of a tool dedicated to its instrumentation.