you have to configure the serial port. the settings for both devices for baud rate, start/stop bits, ... have to match. then there are libraries in go like https://github.com/jacobsa/go-serial that enable standard serial port communication with that you can also use any hex values.
i can not say why the
USBSp is sent because you did not post any code and gave no information what libraries you use. very likely this is not generated by the kernel module and instead by higher layer software because the kernel module used is
USBSp does not appear in the source code :
also not in kernel module
ftdi-sio ( if you use ftdi chip )