Abstract : It is largely recognized that the architectures of embedded systems are becoming more and more complex both at hardware and software levels. Despite the significant advances in the development tools, developing the software of such systems while ensuring their safety is still a difficult task. In this paper, we propose an engineering methodology to ease the development of safe software systems. It consists of four main phases: system modelling and validation, code generation and integration, static code analysis, and dynamic code analysis. This methodology is realized using CEA LIST open-source development platforms: Papyrus, Frama-C, and UNISIM-VP. These platforms are results of many research and industrial projects such as FP7-SafeAdapt, FUI-EQUITAS, FP7-STANCE, CATRENE-OpenES, and FSN-SESAM Grids.