NodeMCU ESP8266 V1 Board ESP-12E WiFi module is the latest version of this popular module and can be used as a WiFi-enabled replacement for an Arduino in many applications.
- ESP8266 NodeMCU V1.0 ESP-12E WiFi Module
Besides adding WiFi capability, the main claim to fame for the ESP8266 processor over the AVR processor of the standard Arduino is that it has a larger 4 MB of Flash memory runs at clock speeds of 80 MHz and can sometimes optionally be overclocked to 160 MHz and therefore has a very fast processing speed.
The Digital I/O all support PWM and interrupts. In addition, they can be configured to have pull-up or pull-down resistors. Though there are 11 digital I/O pins, 2 are typically reserved for use as the TX/RX lines if serial communications are used which leaves 9 digital I/O.