The serial port on the PC is generally ttyS, the Linux serial port on the board is generally called ttySAC, and the USB port to serial port is ttyUSB
If an external serial card is inserted, the default is ttyS* under dev. Generally, ttyS0 corresponds to com1, and ttyS1 corresponds to com2.
1. View the driver information of the serial port
#cat /proc/tty/driver/serial
2. View the baud rate of the serial port
# stty -a -F /dev/ttySAC2
3. View the permission information and name of the serial port
# ls -l /dev/tty*
4.
# cat /proc/tty/drivers
# grep tty /proc/devices
Linux kernel device driver module automatic loading mechanism
http://blog.csdn.net/smstong/article/details/9836589
Difference between /dev, /sys/devices and /sys/dev
http://blog.csdn.net/xy010902100449/article/details/46473031