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
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
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
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
1 vote
1 answer
289 views

NodeMCU not responding AT after blink app

I've just bought NodeMCU LoLin ESP8266, I tried to send AT commands (after spending days on ESP8266-01) and everything was okay. Than I've uploaded the Blink example to the board, after that moment it'...
Sahin's user avatar
  • 13
1 vote
1 answer
205 views

How to publish on Pubnub with node mcu?

I have node mcu and i am trying to use the example code on github and pubnub blog to send a msg as an experiment but can't figure how to do it. I used 2 example as the reference - https://github.com/...
Sultan Morbiwala's user avatar
1 vote
2 answers
6k views

NodeMCU 1.0 - Exception 9 `Fatal exception 9(LoadStoreAlignmentCause):`

I am getting this error in my code. Fatal exception 9(LoadStoreAlignmentCause): Using core version 2.4.2 Stack trace Decoding stack results 0x40213e9c: dns_gethostbyname at core/dns.c line 1472 ...
tony gil's user avatar
  • 362
-1 votes
1 answer
803 views

NodeMCU and expected ';' before wrong ' " '

I am creating a home weather station but the Arduino IDE shows "expected ';' before 'viewport'". It detects wrong quotation marks. My code: String message2 = "<!DOCTYPE html>"; ...
Milan's user avatar
  • 35
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
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
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
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
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
1 answer
556 views

NodeMCU Power supply

I got a question about externally powering my NodeMCU V3. It has an onboard voltage regulator (3v3) which breaks out to 3 header pins. Now I want to power 3v3 from an external board. Can I supply 3v3 ...
sanrays10's user avatar
2 votes
1 answer
2k views

Why do ESP boards break out the SPI flash pins?

I have an ESP32 development board and a NodeMCU board here. Both breaking out the pins for the SPI flash of the ESP. These pins are mentioned in standard pinout descriptions as must/should not connect....
chrisl's user avatar
  • 16.1k
2 votes
1 answer
6k views

nodeMCU - Millis() - Simple Counter - How long is LED on?

PROGRESS, now I have this (WITH GREAT HELP): void setup() { Serial.begin(9600); // initialize digital pin 13 as an output. } uint32_t timer_start = 0; int timer_running = false; void loop() { // ...
AgoraLive's user avatar
2 votes
1 answer
11k views

What is the use of reserved pins and SDD2, SDD3 pins of the NodeMCU?

How to use the reserved pins on the NODEMCU? What is their use? Also what is the use of SDD pins? Thanks.
Harry Karwasra's user avatar
1 vote
0 answers
910 views

Can someone help me to change this code to u8g2

I would like to change this clock to u8g2. It works fine with the esp8266 and oled 128x64. I would start by including the u8g2 library with #include and all display. with u8g2. replace. What else ...
else's user avatar
  • 11
1 vote
1 answer
871 views

YL-38 output to NodeMCU v1.0 analog input

Using a YL-38 and NodeMCU v1.0 I am trying to achieve what the first link is doing, take a soil moisture reading. I've done this on an arduino, but the conversion from an arduino nano to a nodemcu is ...
Doug Clark's user avatar
1 vote
2 answers
3k views

NodeMCU burned, did I something fundamental wrong?

I have a NodeMCU where I connected a LED strip (WS2812b, which operates at 5V). NodeMCU is powered via USB 5V. The used power adapter can supply 2.5A max. I don't have a separate power supply for ...
casper's user avatar
  • 113
1 vote
1 answer
487 views

5V 10A 4 channel relay to 2 lights15W light in series in 220V AC supply

I am trying to setup my first relay module with live environment. I have attached the relay module image below. Which I am using to control 4 devices in my switch board as follows: Fan (working ...
user3201500's user avatar
1 vote
3 answers
16k views

Communication via IP adress with Arduino IDE and ESP8266

I have two Arduino boards and two ESP8266 modules with the NodeMCU firmware, and I want to make this: One Aruino will be connected to one module and a vibration sensor, and when this sensor detects ...
Daniel Corona's user avatar
1 vote
2 answers
30k views

NodeMCU power consumption measurement and DeepSleep

I'm working on a project using a nodeMCU using a ICR14500(3.7V and 700mAh) battery and I'm experienced some issues when I try to estimate the total current consumption. Firstly I experienced some ...
rdiaz82's user avatar
  • 129
0 votes
1 answer
214 views

LED doesn't completely turn off with digitalWrite(led, LOW);

When I was testing out a program I found a strange behavior of ESP8266. LEDs don't turn off completely in the first digitalWrite(led, LOW), just the brightness of the LED goes down, but it does turn ...
tatu101's user avatar
  • 73
0 votes
1 answer
1k views

NodeMCU Exception 28 - intermitent problem

I am SOMETIMES getting exception 28 when running a web upload (over a very unstable rural internet CPE link - wifi is fine, but feed goes on and off): Decoding stack results 0x40213b8c: ...
tony gil's user avatar
  • 362
0 votes
1 answer
9k views

How to fix 12V RGB LED Strip connection to NodeMCU?

I am trying to hook 12V RGB Led Strip (LTROP SMD 5050 RGB LED Light Strip) to a NodeMCU unit. I know there are many different tutorials on this and I am very new to wiring and electric circuits. I ...
abolotnov's user avatar
  • 111
0 votes
1 answer
929 views

How to connect Sparkfun M6E Nano UHF Rfid reader and ESP8266 NodeMCU 0.1

I am using an ESP8266 NodeMCU v0.1 and Sparkfun M6E Nano UHF Rfid reader. How to connect NodeMCU to M6E Nano UHF Rfid reader?
Eza's user avatar
  • 19
0 votes
2 answers
5k views

NodeMCU V3 + SD Card with Arduino IDE Not working

I am trying to connect CATALEX MicroSD Card adaptor to new NodeMCU V3 and PIN configuration are as below, NodeMCU ---------> SD Card GPIO13 (D7) ------> MOSI GPIO12 (D6) ------> MISO GPIO14 ...
Akshay's user avatar
  • 3
0 votes
1 answer
3k views

MQTT not working on ESP8266 (Nodemcu 0.9)

I'm trying to use NodeMCU on my ESP8266 (NodeMCU 0.9) but the board keep crashing and I don't understand why. I tested the mqtt broker using command line and it works perfectly, so I can suppose that ...
Timmy's user avatar
  • 185
0 votes
6 answers
14k views

NodeMCU powered with battery and use WiFi

I'm running a project with a nodeMCU DevKit and my project runs smooth if I run it connected through the usb wire to the computer. I need to run my project using battery and I tried with a ICR14500 ...
rdiaz82's user avatar
  • 129
0 votes
2 answers
1k views

Sensors go crazy on external power

For few days, I am trying to figure out, why my sensors do not work on external power. I bought NodeMCU along with couple different sensors etc. I was happily working with them, connecting them one by ...
ojek's user avatar
  • 121
-1 votes
1 answer
2k views

NodeMCU max draw

1) what is the max draw I can draw from NodeMCU V3 logic and 5v pins? 2) Also, I heard i draw with it more than 500mA, the PC USB port stops working. Is that information actual? Because USB 3 port has ...
T0biasCZe's user avatar
-1 votes
4 answers
3k views

No Response to AT commands

I'm unable to communicate with my nodemcu ESP8266 module using the AT commands. The module does not return 'ready' on the serial monitor and entering AT commands has no effect at all. I am able to ...
Sumanth's user avatar
  • 177
-1 votes
2 answers
6k views

Serial Monitor not properly interpreting data from my NodeMCU V3

I've just received several LoLin NodeMCUs from a 'cheap Chinese ebay vendor'. They're working well except for the fact that I'm getting garbage in the Arduino IDE Serial monitor. I am able to: Load ...
Bob Johnson's user avatar