The system is Gentoo Linux，installed minicom.
On Windows, you can use PuTTY to communicate with the development board through a serial port
Why is there no ttyS* in my Linux host /dev directory?
dmesg | grep tty
[ 0.000000] printk: console [tty0] enabled
[ 0.923092] 00:05: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
[ 4.754282] systemd[1]: Created slice system-getty.slice.
[ 5.640094] usb 3-3: ch341-uart converter now attached to ttyUSB0
Why is it still disconnected?
Which ROCK Pi S system do you use?
rock pi s d4 512MB without wifi and bluetooth
Armbian Focal minimal legacy kernel 4.4.y
Minicom on other Linux distributions is working, with the exception of Gentoo.