Questions tagged [nodemcu]

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

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21
votes
3answers
115k views

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 ...
2
votes
4answers
21k 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 ...
2
votes
1answer
671 views

How to send UDP data packet between two access point?

I am new to arduino programming and nodeMcu boards.I have two ESP8266 bards as access points and one board get some data form WiFi stations and resend that data to other access point. but the problem ...
1
vote
2answers
3k 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, ...
1
vote
1answer
171 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/...
1
vote
1answer
197 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'...
0
votes
1answer
816 views

How to acheive fast and reliable communication between NodeMCUs?

I have two NodeMCU which have to send data to a server (also a NodeMCU). I want to acheive speed of atleast 10Hz because the sensor sends it at that rate. I have tried websockets and couldn't get ...
0
votes
1answer
3k 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 ...
-1
votes
1answer
669 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>"; ...
5
votes
5answers
70k 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 ...
14
votes
3answers
42k 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 ...
15
votes
4answers
27k 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 ...
4
votes
1answer
832 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 ...
1
vote
2answers
25k 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 ...
0
votes
1answer
636 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?
3
votes
1answer
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 ...
3
votes
1answer
571 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....
2
votes
1answer
81 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 ...
2
votes
1answer
5k 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() { // ...
1
vote
0answers
612 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 ...
1
vote
1answer
757 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 ...
1
vote
1answer
5k 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.
1
vote
3answers
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 ...
0
votes
2answers
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 ...
0
votes
1answer
365 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 ...
0
votes
6answers
13k 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 ...
0
votes
1answer
8k 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 ...
0
votes
1answer
448 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: ...
0
votes
1answer
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 ...
-1
votes
1answer
565 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 ...
-1
votes
5answers
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 ...
-1
votes
2answers
5k 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 ...