Test ESP8266 WiFi
https://raspberrypi-guide.github.io/networking/create-wireless-access-point
https://learn.sparkfun.com/tutorials/setting-up-a-raspberry-pi-3-as-an-access-point/all
https://woodsgood.ca/projects/wp-content/uploads/ESP8266ATCommandsSet.pdf
https://randomnerdtutorials.com/esp8266-pinout-reference-gpios/
https://www.instructables.com/Connect-an-ESP8266-to-your-RaspberryPi/
https://arduino-esp8266.readthedocs.io/en/latest/esp8266wifi/readme.html