看https://github.com/grbl/grbl,IMPORTANT INFO WHEN UPGRADING TO GRBL v0.9i:
Baudrate is now 115200 (Up from 9600).
Variable spindle is now enabled by default. Z-limit(D12) and spindle enable(D11) have switched to access the hardware PWM on D11. Homing will not work if you do not re-wire your Z-limit switch to D12.