In recent years, the ESP8266 has become more and more the universal microcontroller that can be used in almost any project. A microcontroller for ~2€ including Wi-Fi and with lots of memory can be found at most at the big brother the ESP32.
The ESP8266 exists in different versions and breakout boards. The most common, because certified, version is the ESP-12 version with all its sub-variants. This one gives access to almost every GPIO and also the ADC, which is not always the case with other versions. But there is also one "disadvantage" ...
A bright blue LED on the PCB of the ESP is indeed handy to see if the ESP is powered. But in projects in which the ESP8266 should be installed as invisibly as possible, this is quite disturbing.
But there are ways to get rid of these LEDs. How to do it and what you have to keep in mind is described in the following article.
Hints for our lovely english readers: Basically, many of the articles on Nerdiy.de are translations from the original german articles. Therefore, it may happen here and there that some illustrations are not available in english and that some translations are weird/strange/full of mistakes or generally totaly wrong. So if you find some obvious (or also not obvious) mistakes don't hesitate to leave us a hint about that in the comment section.
Also please don't get confused, that instead of a "dot" often a "comma" is used as decimal separator. 🙂
Safety instructions
I know the following hints are always a bit annoying and seem unnecessary. But unfortunately, many people who knew it "better" from carelessness lost their eyes, fingers or other things or hurt themselves. In comparison, a loss of data is almost not worth mentioning, but even these can be really annoying. Therefore, please take five minutes to read the safety instructions. Even the coolest project is worth no injury or other annoyance. https://www.nerdiy.de/en/sicherheitshinweise/
Affiliate links / advertising links
The links to online stores listed here are so-called affiliate links. If you click on such an affiliate link and store via this link, Nerdiy.de receives a commission from the online store or provider concerned. The price doesn't change for you. If you do your purchases via these links, you will support Nerdiy.de in being able to offer further useful projects in the future. 🙂
Requirements
Helpful Articles:
In the case of the hardware solution, you should have already dealt with the soldering iron.
For this you can find more information in the article Electronics—My friend the soldering iron.
Required tools:
-none-
Required material:
In the following list you will find all the parts you need to implement this article.
The software solution
The simpler solution to the "LED problem" that requires no soldering iron or other tools is the software solution. Because a look at the circuit diagram of an ESP8266 in version 12 shows that the cathode of our problem LED (in the circuit diagram "LED1") is connected to the GPIO02 via a resistor. And if there is a GPIO, there is also a switching option by software. 🙂
It should be noted that the switching logic of this LED is inverted because the LEDs "negative pole" is connected to the GPIO. In other words, if the GPIO02 is HIGH, the LED turns off, but turns on when it is LOW. This must be considered when switching the GPIO2.
In case you program your ESP8266 yourself via the Arduino IDE, the following code is enough to deactivate the LED.
#define GPIO02 2 pinMode(GPIO02, OUTPUT); digitalWrite(GPIO02, HIGH);
If you happen to use ESPEasy as the "operating system" for the ESP8266, you can use the following built-in function.
The hardware solution
The hardware solution is the solution of choice if you want to disable the LED but still want to use the GPIO02 to interact with other hardware. The LED is simply soldered out. Especially the GPIO02 or D4 is on Wemos D1 mini-boards is likely to use - at least from me - because he is right next to the "5V" and "GND" pins.(Perfect to connect one of the famous WS2812B LED stripes) The only drawback: The LED is usually destroyed, but in most cases you can get over it.
This is admittedly the most radical solution. At the same time, it is also the only solution to disable the LED if you want to use the GPIO02 for other outputs at the same time.
Additional information
https://vietnhap.com/dien-tu-so/tom-tat-esp8266-va-phan-loai-cac-ho-esp.htm
Have fun with the project
I hope everything worked as described. If not or you have any other questions or suggestions, please let me know in the comments. Also, ideas for new projects are always welcome. 🙂
P.S. Many of these projects - especially the hardware projects - cost a lot of time and money. Of course I do this because I enjoy it, but if you appreciate that I share this information with you, I would be happy about a small donation to the coffee box. 🙂
English 
Deutsch 
Français 
Español 
Português do Brasil 
Nederlands