Just a quick help for this unit. It does not compile unless
- You load the GFX library form https://github.com/adafruit/Adafruit-GFX-Library,
- Unzip and rename the folder to: “Adafruit-GFX-Library”
- move this folder to your Arduino IDE installation libraries folder
- Finally, re-open your Arduino IDE
PS: Great book, great job, love it.