These files are provided only as a functional sample. For real applications they must be replaced with the files provided by the vendor. Extensions to the ARM CMSIS files: - the assembly startup file was reimplemented in C, and split into multiple files, portable for the entire Cortex-M family: src/newlib/_startup.c src/cortexm/exception_handlers.c - the chip interrupt handlers must be added to the file src/cmsis/vectors_stm32f0xx.c Use of assembly files --------------------- The current version of the Eclipse managed build plug-in does not process .s, but only .S. If you want to use the assembly startup_Device.s, you must exclude the _startup.c and exception_handlers.c from build, and rename the vendor provided assembly file to startup_XXX.S, where XXX is the actual device name.