Product description
The Raspberry Pi 5 has a dedicated debug UART interface. max baud rate of 921,600bps with configurable EEPROM parameters.
It is always active and enabled, and provides direct access to early boot and firmware information, as well as the Linux terminal console after boot.
By default, it provides a 115,200 baud 8N1 connection on /dev/ttyAMA0 (alias /dev/SerialO).