Espressif ESP8266 User Manual page 37

changed the pin naming for their LUA firmware. If you are programming a NodeMCU module
you can use the printed D# names. If you use a generic ESP8266 module then you have to
use the corresponding GPIO numbers. Here is a table of the mapping:
NodeMCU Index
D0
D1
D2
D3
D4
D5
D6
The NodeMCU Index is the name on the board, whereas the ESP8266 Internal column is the
one you use in the Arduino IDE code: e.g. D5 on the board is pin GPIO14 in C/C++.
ESP8266 Internal
GPIO16
GPIO5
GPIO4
GPIO0
GPIO2
GPIO14
GPIO12
NodeMCU Index
D7
D8
D9
D10
D11
D12
ESP8266 Internal
GPIO13
GPIO5
GPIO3
GPIO1
GPIO9
GPIO10