Questions tagged [nodemcu]

For questions about NodeMCU, an open source IoT platform which includes firmware for running on the ESP8266.

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25 votes
3 answers
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NodeMCU - Vin pin as 5V output?

I know that Vin can be used to power the board but have also been reading that it can be used as a 5V output. Is it possible to assign Vin as an output as I would any other GPIO? If I want to power ...
acpilot's user avatar
  • 643
17 votes
2 answers
45k views

Difference between these two NodeMCU boards?

I recently received a NodeMCU (identical to the one shown in the first picture below) and originally, I was unable to connect it to my computer which eventually turned out to be driver issues; however,...
Tom's user avatar
  • 329
16 votes
3 answers
52k views

Does the Node MCU v3 (LoLin) not have a builtin led?

Trying a simple led blinking program I could not get the builtin led on a LoLin Node MCU v3 working. The LED_BUILTIN constant is set to pin 16 / GPIO16 / D0. Reading several articles and QA I think ...
Jan H's user avatar
  • 271
15 votes
4 answers
31k views

ESP8266, Arduino IDE vs Lua?

I'm planning to buy an ESP8266. Do I really need to learn Lua to play with it? I have seen some people using it with the standard Arduino IDE. Do you need a custom firmware to use the Arduino IDE ...
n0tis's user avatar
  • 375
14 votes
5 answers
38k views

NodeMCU - use flash button as input in loop()

I couldn't find a proper answer on the net so I came here as a last resort. So I want to use the FLASH button as an input in the loop() method. Is there a way the check if it's pressed or not?
sOnt's user avatar
  • 145
9 votes
2 answers
18k views

What is difference between NodeMCU and esp8266?

Since I have no previous experience in electronics I'm getting quite confused while coming across these two terms ..I'd like to know whether they're the same or different.
User 1426833's user avatar
9 votes
1 answer
19k views

In ESP-12E NodeMCU, what's the pin number of A0?

In ESP-12E NodeMCU, all digital pins can be called with a number. Here is the list: static const uint8_t D0 = 16; static const uint8_t D1 = 5; static const uint8_t D2 = 4; static const uint8_t ...
pfernandez's user avatar
6 votes
5 answers
78k views

How to make a 5-volt relay work with NodeMCU?

I have hooked up 2 channel 5-volt relays with NodeMCU v1.0 as shown in the fritzing below. Relay are powered with a different power source than NodeMCU. As of now, I am powering the NodeMCU from my ...
Ciasto piekarz's user avatar
5 votes
2 answers
38k views

How to determine Flash size?

I need to determine the flash size of my ESP8266 on my NodeMCU module in order to flash the AT firmware onto the board. Apparently different boards come with differently-sized flash memories. Can ...
Sumanth's user avatar
  • 177
5 votes
1 answer
17k views

Vin & VU pins of NodeMCU V3

Can we use the vin pin of the lolin v3 nodeMCU as a 5V supply. If yes, i checked mine with a multimeter. At max, it gives a voltage of 2V. Is my pin blown out? Also, can use the VU pin as a 5V supply? ...
Yash Shah's user avatar
5 votes
2 answers
24k views

Simple GET request with ESP8266HTTPClient

I am trying to do a simple GET request. But I always get status code -1. Here is my complete code. #include <Arduino.h> #include <ESP8266WiFi.h> #include <ESP8266HTTPClient.h> ...
Ccr's user avatar
  • 279
5 votes
2 answers
6k views

NodeMCU wiring for Serial1?

I'm trying to get telemetry data to be sent out Serial1 on the NodeMCU board. I read that TX is (by default) mapped to pin D4. Ultimately, there will be a Raspberry that will be listening for ...
pathrider's user avatar
  • 161
4 votes
4 answers
53k views

ESP8266 not connecting to WiFi

I am trying to send the temperatures from an DS18B20 to ThingSpeak, using an ESP8266. You can see the code I am using for that. When I run the code I do not get any errors. In serial monitor it just ...
Ali Karim's user avatar
4 votes
2 answers
11k views

Multiple libraries were found for "WiFiClient.h" using nodemcu

I am trying to send HTTP requests from nodemcu so I started by uploading the esp8266 library but when I run the following code #include <ESP8266HTTPClient.h> #include <ESP8266WiFi.h> ...
Ela Hidri's user avatar
  • 111
4 votes
1 answer
1k views

Ubuntu Serial Port Briefly showing on arduino IDE

I am using a NodeMcu with Arduino IDE on Ubuntu. I have managed to upload the blink script and it work. Now, when i plug the nodemcu, the serial port /dev/ttyUSB0 is briefly available in the IDE. ...
Justin Mayer's user avatar
4 votes
1 answer
8k views

Turn off the second builtin Nodemcu 0.9 led

I'm making a low energy consumption device so I'd like to turn off all the led when I'm idle. Unfortunately the nodemcu turn on a blue led while I'm idle (during delay(ms)) Here is my code: #define ...
Timmy's user avatar
  • 185
4 votes
1 answer
16k views

powering Nodemcu using Vin

Forgive me for this really dumb question. I am an amateur in electronics, and im trying to wrap up my head around this question and im not able to do so. Need your help. Im trying to power up a ...
bukke hari prasad's user avatar
4 votes
3 answers
23k views

WebSocketsServer.h: No such file or directory

I'm trying use the NodeMCU WebSocket. I downloaded the required libraries from: https://github.com/Links2004/arduinoWebSockets and pasted them in my Arduino libraries folder. I uploaded my code but ...
Zainab Shah Khan's user avatar
3 votes
4 answers
28k views

Use 5V pH sensor with 3.3V NodeMCU

I'm trying to use a pH probe with NodeMCU, the problem is that NodeMCU is 3.3V and the pH analog sensor requires 5V, at first I thought using the VIN pin but didn't work, then I used the VU pin from ...
Javier Guerrero's user avatar
3 votes
1 answer
5k views

NodeMCU does not boot up when GPIO pin is high

I have a NodeMCU board connected to a door and there is a micro switch that makes one GPIO pin (GPIO15 - D8 in this specific case) go high when the door opens. My problem is if I lose power while the ...
Ε Г И І И О's user avatar
3 votes
4 answers
26k views

How to change the default name of ESP8266-12E module

Is there any way to change the default name (ESP_xxxxx) that the module generates?
Sr Julien's user avatar
  • 131
3 votes
1 answer
3k views

Why Smart Plugs don't require setting port forwarding on router and how to accomplish this with NodeMCU (ESP8266)

I have a NodeMCU (ESP8266) board that I use to control some devices over the internet. To be able to access it I have to enable port forwarding on my router and set the port manually like in the image ...
Slaven Tojić's user avatar
3 votes
3 answers
5k views

D1 Mini; is there a fuse?

While this board (listed on ebay as D1 Mini NodeMcu Lua WIFI ESP-12F ESP8266 WeMos 4M Bytes Development Board Kit) was powered by usb, I accidentially shorted between the gnd (G) and 5v pins on the ...
Lenne's user avatar
  • 163
3 votes
2 answers
751 views

I2C protocol doesn't work properly

I am trying to make I2C Communication between NodeMCU and arduino Uno boards. However it is not working properly. It makes communication for once time when i uploaded code. Master Device Code(NodeMCU ...
Snefru Clone's user avatar
3 votes
1 answer
6k views

ESP.deepSleep() - over and over?

Important note: the esp.deepsleep function uses microseconds, not milliseconds. I posted another question here asking for clarification on how an RTC can be used to put a NodeMCU 12 to sleep for a ...
acpilot's user avatar
  • 643
3 votes
1 answer
926 views

use Nodemcu to program Attiny85

I have a dev board for my attiny85. when connecting it to the computer I get "unknown USB device(device descriptor request failed)" although I have the needed drivers, so I thought of trying ...
tal itshak's user avatar
3 votes
1 answer
2k views

Flashing an ATtiny85 with a NodeMCU?

I recently purchased a Digispark for some of my smaller electronics projects. After it initially being a great little board, I soon found myself unable to flash the board in the same way I had done ...
Rocco's user avatar
  • 165
3 votes
1 answer
96 views

Correct way of having loop end when required?

I'm brand new to Arduinos. I'm currently trying to modify a script from here which at the moment, simply turns an LED on or off depending on which HTTP GET request it receives. However, I want to ...
Tom's user avatar
  • 329
3 votes
1 answer
729 views

How to program Esp8266 remotly via wifi?

I hope it's not a sci-fi for arduino. But I saw that dual system with two MCU can program each other via radio connection. It has been done in experimental space cube projects. It is theoretically ...
Sahasrar's user avatar
  • 161
3 votes
1 answer
131 views

NodeMCU V3 GOT OVERHEATED AND DIED

My NodeMCU V3 got overheated and died. Please help me figure out what i did wrong. Brief Desrip: Project is an RC Car on ESPNOW Protocol. Transmitter setup have an Arduino Nano to take values from Two ...
NonTechGuyinTech's user avatar
3 votes
1 answer
4k views

How to flash a NodeMCU (ESP8266) with an external FTDI programmer?

Hi my USB to UART bridge (CP2102) seems to be broken on one of my NodeMCU Dev Boards with ESP8266. It seems to be just that specific board since all other boards that I have can be flashed without ...
shyney's user avatar
  • 73
3 votes
1 answer
786 views

Ultrasonic Sensor(HC-SR04) recording random distance

I am am trying to make a code which automatically controls relay on basis of ultrasonic sensor measurements. I am using a nodeMCU as a microcontroller rather than an arduino. The relay and the ...
Shubham Bajaj's user avatar
3 votes
1 answer
5k views

How to flash pre-compiled bin files into NodeMCU using Ardunio IDE

How to flash pre-compiled binary into NodeMCU using Ardunio IDE. Since every time it require to compile and flash it. Is there way to flash binary alone to nodeMCU via Arduino IDE ? One can export ...
vimjet's user avatar
  • 169
3 votes
1 answer
367 views

Program nodeMCU Over the Air (OTA)

I have a Lolin NodeMCU V3 with a broken USB port: no power, no data. It does show up on WIFI as AI-thinker_xxx, I can connect, but what can I do next? Is there a way to program the NodeMCU Over the ...
Janghou's user avatar
  • 156
3 votes
0 answers
72 views

ESP8266 requires two resets to wake up from deep sleep [duplicate]

I'm working with the following circuit using a NodeMCU: I have the solder jumper bridged between RST and BTN. In addition to what's in the schematic, pins 2, 3, and 4 of J1 are connected to the ...
Florian Ragwitz's user avatar
3 votes
0 answers
1k views

how to get live view of esp32cam at remote sever using ssh tunneling?

I have found many projects involving esp32cam, but in all projects video is being seen on local server only.For its of no use.As for a home security project user can view the video at remote location ...
user65895's user avatar
2 votes
1 answer
7k views

How to get current WiFi signal strength?

I have a LCD display where in I'm displaying a WiFi signal logo. I want to reduce the number of bars on the logo, indicating that the signal strength is dropping. I got the reducing bars on the LCD ...
Coder9390's user avatar
  • 472
2 votes
2 answers
6k views

Arduino slave with 2 masters sharing the same I2C Bus?

Consider a scenario where two (or more) master devices (the NodeMCU's, in this case) share an I2C bus with one (or more) slave device(s), like thus: Would this be a feasible setup? In other words, ...
tony gil's user avatar
  • 362
2 votes
2 answers
24k views

EEPROM put and get not working on ESP8266 (NodeMCU)

The Arduino documentation provides two examples to store data in the EEPROM. https://www.arduino.cc/en/Reference/EEPROMPut stores data in the EEPROM and the EEPROMGet example reads the data back and ...
Ale's user avatar
  • 29
2 votes
4 answers
26k views

ESP8266 NodeMCU first WS2812 LED lights up green

I'm trying to power some WS2812 LEDs from my ESP8266 ESP-12E NodeMCU board (circuit here). I'm simply trying to use the NeoPixel Strandtest which works perfectly on my Arduino UNO with the same LED ...
MortenMoulder's user avatar
2 votes
2 answers
11k views

NodeMCU (Arduino IDE) 'DynamicJsonBuffer' was not declared in this scope

#include <Arduino.h> #include <ESP8266WiFi.h> #include <ESP8266WiFiMulti.h> #include <ArduinoJson.h> #include <ESP8266HTTPClient.h> #define USE_SERIAL Serial ...
Adnan Sabbir's user avatar
2 votes
1 answer
2k views

Voltage, current measurement from solar panel using INA219 and ESP-12F

I recently started tinkering with ESP-12F thus I am a novice here. As a standard novice project, I am making a standalone weather station for my living room. I want to use solar panels to charge the ...
blackbug's user avatar
  • 123
2 votes
2 answers
2k views

Lolin NodeMCU V3 and 5V sensors

I am new to Arduino and electronics so please correct me if I made a mistake. Many sensors and actuators require 5V. The Lolin NodeMCU V3 has outputs of 3.3V. I want to have them working together. ...
user1420303's user avatar
2 votes
4 answers
5k views

PIR motion sensor (HC-SR501) false results with NodeMCU

I have a PIR sensor which I use to detect the motion and turn ON and OFF the lights on the basis of it. I have PIR connected with NodeMCU (ESP8266) based board. I find that sometimes it trigger ...
user3201500's user avatar
2 votes
3 answers
8k views

How to connect MPU9250 with NodeMCU using SPI or I2C Slave?

I want to connect 3 MPU9250 sensors, but since there is just one I2C bus, so there are another 2 sensors I want to connect through SPI. Library used - https://github.com/bolderflight/MPU9250/blob/...
suu's user avatar
  • 85
2 votes
2 answers
2k views

Setting pinMode(pin,input/output) as per user requirement

I am working on arduino IDE and esp8266 nodemcu. As i am going through the IDE I saw that there is a structure of void loop() and void setup() and all examples in the internet included defining the ...
Wan Street's user avatar
2 votes
1 answer
6k views

Compilation Error in nodeMCU along with oneWire temperature sensor ds18b20, and 2x16 LCD display (not I2C)

I am using nodeMCU along with oneWire temperature sensor ds18b20, and 2x16 LCD display (not I2C). I am using Arduino IDE to program nodeMCU. I am getting a compilation error: C:\Program Files (x86)\...
Bigyan Chapagain's user avatar
2 votes
1 answer
6k views

NodeMCU serial port - use with computer and device at the same time

I'm trying to understand how serial communication for ESP8266 in NodeMCU actually works. I found a quote saying that normal Serial is mapped to ports GPIO 1 (TX) and GPIO 3 (RX). They are even labeled ...
kubal5003's user avatar
  • 143
2 votes
2 answers
762 views

esp2866 powered externally not working

I got a beginner level problem. I got two esp2866 nodeMCU, they both work with the usb cable and I can get the blink program to run though it. Running them with external power doesn't seem to work ...
bhenriksson's user avatar
2 votes
1 answer
1k views

Can you power the ESP8266E-12 with any of the 3.3V pins?

If I want to operate the NodeMCU on the 3.3V input with 2.5V to 3.6V; can I use any of the 3.3V pins to do so?
Altus's user avatar
  • 123

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