Hi, David I checked your compiler environments.(gnuarm) I think that you should change path directory : Before : c:\ethernut-4.1.9\nut\tools\win32;C:\Program Files\GNUARM\arm- elf\bin; After : c:\ethernut-4.1.9\nut\tools\win32;C:\Program Files\GNUARM\bin . Try it. Young-Dong Yoo