This pin is on the rear of the ESP8266 module, and on many development boards, it isn’t even connected. ... Parts Tagged circuit design, custom PCB, esp-12f, ESP8266. Post navigation.

The official hardware for ESP-RFID can be purchased through Tindie with or without an installed ESP-12F module, but as it’s a fully open source project, you’re also free to build your own ...

If you take a deep look at the D1 Wi-Fi board, you will see that it is different from the claimed to be new version WeMos D1 R2. That is because the latter (D1 R2) has a ESP8266-12F (Not 12E) Wi-Fi ...