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9 months ago
This question already has an answer here:
9 months ago.
I'm trying to connect 3 LEDs to a LoLin NodeMCU ESP8266. It seems that several or "all" of the digital pins have some special use that prevents me from using them.
If I connect the LEDs (and set pinmode to output) to D0, D1 and D2, then the blue bootloading LED will glow constantly, and the code does not seem to run at all (nothing in serial output).
D3 seems to constantly have high power, regardless what I code it to.
If I connect the LEDs (and set pinmode to output) to D1, D2 and D4, then the blue bootloading LED will glow constantly, and the serial output is garbled, but I guess the code is running.
If I connect the LEDs (and set pinmode to output) to D5, D6 and D7, then the blue bootloading LED will glow constantly, and the serial output is garbled, but I guess the code is running.
Yes, I have checked the baud rate, that's not the problem.
What's up with this?
Jun 13, 2022 at 16:30
This link at
In order to use digital pins, you should select GPIO numbers. For example, the D7 pin is defined as GPIO13. So you should set up the pin number 13 whenever you want to use D7 in your program. Also, you can use pin D2(GPIO4) as SDA and pin D1(GPIO5) as SCL
Jun 13, 2022 at 16:35
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