GPIO15 not available for general purpose GPIO and causes issues flashing D1 Mini

[jessedc]

Hi,

Thanks for this project, I have really enjoyed putting it together.

The README suggests connecting the screen's CS pin to GPIO15, which I found caused issues flashing the D1 Mini. The ESPHome ESP8266 documentation says GPIO15 is a "Special Pin" used to control the boot mode and isn't available for general purpose GPIO, which explains my issue.

I swapped the CS pin from GPIO15 to GPIO5 which is available for general purpose GPIO and things are back to working.

May I suggest modifying the README to replace the reference to GPIO15 with GPIO5.

An example configuration YAML would look like this:

spi:
  clk_pin: 14 # or GPIO14
  mosi_pin: 13

display:
  - platform: waveshare_epaper
    id: epaper_display
    cs_pin: 5
    dc_pin: 12
    busy_pin: 16
    reset_pin: 4
    model: 4.20in
    update_interval: 30s
    lambda: |-

# etc

[maxmacstn]

Thank you very much. I'll update the readme and the code according to this suggestion.