The D1 R2 is a mini wifi board based on the ESP-8266EX. 11 digital input/output pins, all pins have interrupt/pwm/I2C/one-wire supported(except for D0) 1 analog input(3.2V max input) Micro USB connection Power jack, 9-24V power input. Compatible with Arduino Compatible with nodemcu /Products/d1_r2.html