树莓派启用TTL串口登录和root登录

启用TTL登录
修改boot分区config.txt
加上

dtoverlay=pi3-miniuart-bt

启用root登录

sudo passwd root
sudo passwd --unlock root

修改/etc/ssh/sshd_config

#PermitRootLogin prohibit-password
PermitRootLogin yes

重启ssh

来源：
https://blog.csdn.net/feitingfj/article/details/56046188
https://www.jianshu.com/p/d6cc514335c7