Installing the library is as easy as checking ... The SPI routines in the ESP32 Arduino port both work just fine. I tested it out by connecting a 25LC256 SPI EEPROM to the chip.

Thanks to their low power consumption, inexpensive price tags, and multiple I/O options, ESP32, Arduino, and other microcontroller ... to the Raspberry Pi, install some add-ons, and use them ...

Plus the Arduino needs to be plugged into the host computer via USB to function, a rather quaint idea to many in 2018. These were just some of the reasons he decided to port Grbl to the ESP32 board.