Hi
Ok i have working now to my satisfaction , I just combined common_data.h and seven_segment_font_data.h into a single file, and it complies.
common_data.h did not have a cpp file as it just a class with no methods.
I don't understand why that would cause SPI.h not to compile just for UNO R4 and the error message. about R_IOPORT_PinCfg or g_ioport_ctrl not declared.
regards