UART1 (ttyS0) Serial Port Configuration
ttyS0 is the secondary Raspberry Pi serial port for communication with peripherals, it is routed to both the HAT connector and the MyPi ASIO connector on the pins below.
The ASIO Connector brings both pins 14/15 and 32/33 out, the default UART1 configuration overlays work with pins 14/15
To enable the UART you only need to configure the the below lines in /boot/config.txt to enable the serial port
You can cross check these lines have been correctly configured by using raspi-gpio get