Arduino Nano / Nano33 support

[ghost]

Hello! Thank-you for providing these great libraries :)

I am trying to use a 2.9inch(b) screen with my new Arduino Nano... unfortunately the example code does not work and nothing appears to happen on the screen.

I have found that it hangs in Epd::Init() where WaitUntilIdle(); is called.
Presumably this is because DigitalRead(busy_pin) never stops being busy (0)?

I am not sure if this is a wiring problem, a compatibility issue, or a bug, but I would be happy to help if you have any ideas!

I would love to make these libraries work with the new Nano33 IOT :)