UNO smd

Tried for sveral days to get brand new board to conect,now returning" bad cpu type in executablle".I am using Fade from the library as pin 13 led 13 is used by the board to indicate it is working correctl(heartbeat or watchdog)As this board is only a couple of weeks old ,I wonder if I need a different driver?It's an Atmel 328 device on the board and an Atmel mega 16u2 acting as a PIA I guess as it is on the TX RX lines connected to the LEDs

If you are using the ‘Fade’ example on your UNO with pin D13, pin D13 is not a PWM pin.

Try pin D9.

Bad CPU type in executable means you are not using latest version of the ide and avr board package on mac OS Catalina, which dropped support for 32-bit executables. Prior to the latest version, arduino used 32-bit executables for the compiler toolchain. Update to latest ide version and make sure you have latest version of official avr board package installed via board manager.