modified library from waveshare for their 3-color 2.7 Inch Pi-HAT ePaper Display. Modified for the usage with the Arduino IDE and the ESP8266 (nodeMCU)
RST: GPIO5 or D1
DC: GPIO4 or D2
CS: GPIO0 or D3
BUSY: GPIO2 or D4
CLK: GPIO14 or D5 or HSCLK
DIN: GPIO13 or D7 or HMOSI
https://www.waveshare.com/wiki/2.7inch_e-Paper_HAT_(B)
https://www.waveshare.com/wiki/File:2.7inch_e-paper_hat_b_code.7z