Good day, I found a couple of more issues with lib\libcpu\m68k\mcf5282\include\mcf5282.h . In this case it is the use of hex masks that are not done properly. #define MCF5282_CFM_CFMCMD_CMD(x) (((x)&7F)) #define MCF5282_FEC_EMRBR_R_BUF_SIZE(x) (((x)&7F)<<4) The constants should be 0x7F. Thanks, Andrei