Datasheet: https://www.espressif.com/sites/default/files/documentation/0a-esp8266ex_datasheet_en.pdf Tech Reference: https://www.espressif.com/sites/default/files/documentation/esp8266-technical_reference_en.pdf PCB Design Guidelines: https://www.espressif.com/sites/default/files/documentation/esp8266_hardware_design_guidelines_en.pdf Pins ==== Multiplexing analog input: https://internetofhomethings.com/homethings/?p=530 Digital: - has hysterisis - Vil = 0.25 * Vin - Vih = 0.75 * Vin ADC: - only 1 analog pin, A0 - 10 bits, 0-1023 - only supports 0.2 - 1.2 V, unless there's on-board voltage divider WeMos D1 Mini ============= - has on board 3V3 ADC divider