The Host Serial interface can replace the USB serial interface after the Baseboard has booted. The Host Serial interface will have much lower bandwidth compared to the the USB serial interface but it might also have lower latency.
The system supports only one HostSerial interface but it can be in any slot. The FPGA Tx line _to_ the host is on the first FPGA pin, Pin #2 on the 8 pin connector. The Rx line for data _from_ the host is on the second FPGA pin, Pin #4 on the 8 pin connector. The third and fourth FPGA pins are unused and should not be connected. The system defaults to using the USB interface. To use the serial interface set it to enabled with the correct baud rate. Only one interface, USB or serial, can be enabled at a time.
config : baud rate and enable flag. The baud rate must be one of 460800, 230400, 153600, or 115200. The enable flag is either 'e' or 'd' to enable or disable the host serial interface.
The enumerator controls access to the host. After enabling the host serial interface be sure to set the enumerator 'port' to the new serial port.
Switch from the FTDI/USB interface to the Tx/Rx interface at 115200 baud.
dpset hostserial config 115200 e dpset enumerator port /dev/ttyS0