The WeMos has a single on board LED so there is no confusion when we refer to the ESPproMon status LED. The NodeMCU has 2 LED’s as shown in the image below.
The LED on the left (connected to GPIO 2, D4) is the status LED for ESPproMon and the LED on the right (connected to GPIO 16, D0) will normally just indicate if the board is powered up (see note 1).
Once you have flashed our firmware to your ESP8266 the LED will blink, very faintly, at 1 second intervals. You need to look closely to see the LED blink but it should be there. This is to tell you that the firmware has loaded correctly and the ESP is ready to be provisioned to our server.
After you have completed the provisioning process the LED will blink, again very faintly, at 5 second intervals and this is the normal status for the LED.
If the status LED is not blinking at all then you should power cycle your ESP and it will blink at 1 or 5 second intervals as indicated above.
This is probably a good place to mention the ESP’s EEPROM. A small flag is set in your EEPROM when it has been provisioned with our server and it disables the ESP’s WiFi Access Point. If you need to enable the Access Point you can manually clear this flag in EEPROM by shorting a wire (or resistor) between ground and GPIO 5 (D1) for a few seconds.
The status LED should then change from the 5 second blink frequency to 1 second, indicating the Access Point is now available and the ESP can be re-provisioned. Please note EEPROM is a special area of memory which is not overwritten when you flash a new bin file to the ESP.
Clearing EEPROM can also be done within the app by pressing the red, CLEAR EEPROM button at the bottom of the SETUP page. When you press the button the label will change to “Press Again” to ensure the button wasn’t pressed by mistake. The terminal in the TARIFF page will confirm the EEPROM was cleared and you can then re-provision your ESP.
Note 1: As GPIO 16 (D0) is used for the RF transmitter, if you are using one, then the second LED on the NodeMCU will go on and off as you use the RF transmitter,