ESP8266 based EPD Google Calendar

The GxEPD2 offers an example code, but it needs some adjustments: 

- You need to change all the "const char" parts of the code to "char". 

- You need to comment out the line of the right display around Line 92:

GxEPD2_3C<GxEPD2_750c, GxEPD2_750c::HEIGHT / 4> display(GxEPD2_750c(/*CS=15*/ SS, /*DC=4*/ 4, /*RST=5*/ 5, /*BUSY=16*/ 16));

- The right pin mapping should be adjusted in the same line 

GxEPD2_3C<GxEPD2_750c, GxEPD2_750c::HEIGHT / 4> display(GxEPD2_750c(D8,  D3, D4, D2));

Upload the code and see the miracle. :D 

The GxEPD2 Library suggests the following mapping  from Waveshare SPI e-Paper to ESP8266 NodeMCU:

• BUSY -> D2
• RST -> D4
• DC -> D3,
• CS -> D8
• CLK -> D5
• DIN -> D7
• GND -> GND
• 3.3V -> 3.3V

It works quite well (with the necessary adjustment in the code)