Features: Compared to old version, the upgraded version has altered pin position and can be compatible for nodemcu. Use BRT (Bias Resistor Transistor), easier to enter flash mode. Optimized circuit makes the system more stable. The new version D1 R2 module meets ESP8266 WiFi. The board is based on the for ESP-8266EX. It has 11 Digital I/O pins, 1 Analog Input pin. OTA -- Wireless Upload(Program). On board switching power supply -- Max 24V input, 5V 1A output. Specification: Size: 70*55*10mm / 2.8*2.2*0.4in Weight: 23g / 0.8oz (approx.) Pin Pin Function for ESP-8266 Pin TX TXD TXD RX RXD RXD A0 Analog input, max 3.3V input A0 D0 IO GPIO16 D1 IO, SCL GPIO5 D2 IO, SDA GPIO4 D3 IO, 10k Pull-up GPIO0 D4 IO, 10k Pull-up, BUILTIN_LED GPIO2 D5 IO, SCK GPIO14 D6 IO, MISO GPIO12 D7 IO, MOSI GPIO13 D8 IO, 10k Pull-down, SS GPIO15 G Ground GND 5V 5V - 3V3 3.3V 3.3V RST Reset RST All of the IO pins have interrupt/pwm/I2C/one-wire support except D0 Programming The D1 R2 has a micro USB for auto programming. You can also program it using OTA. Warnings: All of the IO pins run at 3.3V. Package list: 1 * Module 1 * Pin Header 1、Compared to old version, the upgraded version has altered pin position and can be compatible for nodemcu. 2、Use BRT (Bias Resistor Transistor), easier to enter flash mode. 3、Optimized circuit makes the system more stable. 4、The new version D1 R2 module meets ESP8266 WiFi. 5、The board is based on the for ESP?8266EX.