这是一篇讲述串口很好的入门教程：
http://users.ece.utexas.edu/~valvano/Volume1/E-Book/C11_SerialInterface.htm
如何显示串口数据：
https://unix.stackexchange.com/questions/117037/how-to-send-data-to-a-serial-port-and-see-any-answer
https://unix.stackexchange.com/questions/22545/how-to-connect-to-a-serial-port-as-simple-as-using-ssh
https://stackoverflow.com/questions/5347962/how-do-i-connect-to-a-terminal-to-a-serial-to-usb-device-on-ubuntu-10-10-maveri
https://stackoverflow.com/questions/8877269/writing-to-serial-port-from-linux-command-line
minicom 教程：
https://www.youtube.com/watch?v=pnU0EE8_o6I
https://www.systutorials.com/docs/linux/man/1-minicom/
https://help.ubuntu.com/community/Minicom