The WeMos D1 mini is a minimal ESP8266 wifi board.
Features
- 11 digital IO, interrupt/pwm/I2C/one-wire supported(except D0)
- 1 analog input(3.2V max input)
- a Micro USB connection
- Compatible with MicroPython, Arduino, nodemcu
Documentation
Schematic V3.1.0[PDF]
ESP8266 Explained: chip vs module vs board