The E-Paper display base class is a subclass of Adafruit_GFX, to have graphics and text rendering. It needs up to 15kB available RAM to buffer the black/white image for the SPI displays, double for ...
The library gives easy control over the 16 pins of the PCF8575 chips. Base address = 0x20 + 0..7 depending on address pins A0..A2. PCF8575C 0x20 to 0x27 need pull up in input mode. See #36, to be ...