Questions tagged [nodemcu]

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

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wdt reset cause:4, boot mode:(3,6)

I'm working on Python and nodeMCU with websocket connection. So, I send a string from Python to nodeMCU and nodeMCU collects the string and decodes to set values to a stepper motor. Initial code ...
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22 views

Send a string from python GUI to NodeMCU serial over wifi [closed]

I have working prototype of sending data from python to Arduino serial using Serial library. But all i want to do it wirelessly. any tips? Also, is it possible to send a string to nodemcu without ...
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32 views

Relay with NodeMCU is not working

I'm using a Relay Channel and NodeMCU(8266-WIFI). When i trigger the connection, LED Turns ON in Node MCU But the Relay connection is not working. I'm not sure what is the issue, Please help to fix it....
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18 views

Arduino Uno + NodeMCU serial to MQTT

I made a pool monitor with ORP + pH + temp sensor. I had everything working (apart from ORP sensor causing interference with pH sensor, but that is a different topic...) for the past couple days in a ...
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41 views

Two way serial communication between arduino mega and NodeMCU

I'm trying to create an IoT device that will collect data from the sensors and display them in a mobile app, also let the user control the device using the mobile app. So I need to set up two-way ...
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42 views

MPU6050 Problem with NodeMCU

I am using MPU6050 as a part of IMU of my drone, and I wrote this program for Arduino Nano to fetch the orientation of the MPU6050 module in 3D space. And that works perfectly fine, but when I ...
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25 views

NodeMCU ESP8266

I am doing a project and using NodeMCU ESP8266. My project includes sensors for UART, I2C and 4 interrupts. I need to read the data from these sensors and get these data via microUSB in real time. ...
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35 views

Fastest Communication from NodeMCU to Arduino Nano

For one of my projects, I need to transmit data from NodeMCU to my Arduino Nano, in real time, I used S-Bus, but it quite unsatisfies me, as, slight latency is taking place. I am transmitting a JSON ...
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19 views

How to wire L293D chip to a nodeMCU?

How do I wire an L293D motor controller chip to a nodeMCU? I have tried to follow the instructions from this tutorial: lastminuteengineers.com One problem. I don't have a 5v pin? Are there any ...
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2answers
49 views

Nodemcu v3 - Power supply via VU pin?

I want to control two hitec hs55 micro servos via a Nodemcu v3. These need at least 4.8 V power supply acc to data sheet. Specs: Hs-55 micro servo: Voltage range: 4.8-6 V Current Drain - no-load (4.8V)...
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33 views

Latency in Websocket

I am using Websocket, for a communication from my mobile phone to a NodeMCU, and transmitting 4 channel, data, through 4 different Websocket Ports. the NodeMCU control code is here: // ============ By ...
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26 views

I2C LCD displaying gibberish

I have connected a I2C LCD with my NodeMCU v3. My pin configuration is as follows: Node MCU ---> I2C LCD GND GND 3V VIN SDA D2 SCL D1 I have been testing a ...
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24 views

ESP8266 NodeMCU 3v3 current for fingerprint sensor

From what i see that 3.3Vpin provide 3.3V and 400mA. The fingerprint module i use is AS608. Connecting the fingerprint module power pin to 3.3V of the nodemcu. From the datasheet it only can handle 3....
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20 views

Node MCU Wifi connection problem

I'm trying to connect my nodeMCU to my WiFi network also i have provided ip address but it keeps printing ........ it is not connecting to the network. Below is my code. #include <ESP8266WiFi.h>...
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Is it possible to access GPIO9 and GPIO10 as DIO?

I have a nodemcu dev board with the esp12 chip. (Not the esp12e one). I have tried to make use of gpios 9 & 10 for digital output. On the board, they are marked as SD2 & SD3. I suppose they ...
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36 views

Sending AT commands to Reyax RYLR890 LoRa modules via additional serial port not working

I am setting up a LoRa module (transmitter) with nodemcu (ESP8266). The module (Reyax RYLR896) accepts AT commands over serial interface. I created an additional serial port using pins D7 and D8 on ...
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33 views

NodeMCU LUA ESP8266 12E Issues with Programming

I recently bought the NodeMCU ESP8266 to work on an embedded project, and for whatever reason, the board will only allow me to upload Arduino sketches when I unplug and replug in the board via the ...
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48 views

ESP8266 NODEMCU V3 web server with MAX7219 and DS3231 RTC

I am using ESP8266 NodeMCU with MAX7219 and a DS3231 teal time clock. I want to display the time and some text. The display is made of 4 FC16 modules which are made of 4 8x8 MAX7219 led matrix modules ...
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39 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 ...
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56 views

Running hardware interrupt function on NodeMCU ESP8266, Exception(0) after four iterations, can't disarm interupt function

I've been trying to test the stability and consistency of hardware interrupts on my NodeMCU ESP8266. I'm using the Arduino IDE. This sketch should not require any external circuitry and I think, but ...
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42 views

NodeMCU EEPROM Stored Datas Deleted Suddenly

In my project i am using nodemcu board.It is clone of Adafruit's huzzah. Last days i faced a problem about eeprom. 1- I have some data and i have to save this datas on eeprom. 2- Data types are ...
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45 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 ...
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67 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....
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39 views

Blink doesn't work on pin D3,D4 and D0 but works on D7

I am facing a strange issue. I am trying to blink an external LED using Wemos D1 mini V2 board. But it is not working. My sketch is as below. int LED = D3; void setup() { pinMode(LED, OUTPUT); } ...
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28 views

How can i send data to phpmyadmin database? using esp8266 nodemcu and max30100

i want to send data from my sensor to database phpmyadmin. but i only get zero values. please help me thank you. void loop() { pox.update(); BPM = pox.getHeartRate(); SpO2 = pox.getSpO2(); // ...
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22 views

LED goes off in nodemcu If I turn on other LED

I developed an android app to control a robot using nodemcu. I have added some buttons to on/off or blink some LEDs. It works fine but, if I on the one LED or drive the robot, the other LEDs goes off. ...
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26 views

Unable to initialize SD card

I am not able to initialize the SD card. Can't find figure out what the issue is. It fails at the condition if (!SD.begin(D8)) { Serial.println("initialization failed!"); return; } I am using D1 ...
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18 views

General help with running 2 motors simultaneously using NodeMCU, on IMU sensor data

IMU Sensor - rotation data Transmitting NodeMCU - Sending rotation data to Console NodeMCU over WiFi Console NodeMCU - controlling motors 2 motors - X axis motor, Y axis motor Motor driver module(...
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28 views

NodeMCU Power Draw and charging Circuitry

I am planning to build a small wireless keyboard, around 5 buttons and 1 rotary encoder, that will connect via WiFi to my Spotify account. For this project, I was looking at the Node MCU for the board....
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2answers
80 views

How to fix memory-leak code in ESP8266/NodeMCU caused by string concenation?

I have following code in loop() in NodeMCU. This part is before setup(): String serial_data_read = ""; // for incoming serial string data String serial_data = ""; // for incoming serial string ...
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36 views

HTU21 on GY-21 breakout board I2C problem

I am interfacing the HTU21D sensor with my nodeMCU v3. All good! I managed to get some readings etc. But when I re-upload my code the device does not respond. If I remove the power supply from the pin ...
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203 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? ...
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1answer
37 views

Print connection password typed by user on NodeMCU Lua ESP8266 ESP-12E

I want to make a WiFi Access point created with the ESP8266. Let's say that the SSID is 'net_work' and the password is '12345678'. When a client tries to connect with a wrong password, I want to ...
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1answer
29 views

How to connect multiple NodeMCUs and 1 PC over wifi and have PC control NodeMCUs? [duplicate]

I am trying to design a laser tag system using multiple NodeMCUs in the guns. I am trying to figure out how to connect and control them over WiFi. I also need a computer connected that will control ...
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17 views

NodeMCU is not working. Only a little orange LED is turning on

Some time ago, i powered a NodeMCU with a 9 volt battery, it worked but the next time i tried to use the board, only a little orange led near the usb connector and reset button turned on. I can't ...
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1answer
39 views

What current is safe for Wemos d1?

I've got 12V / 400mA power supply for my Wemos D1 R1, and I'm using VIN output(I need 12V for led strip). I need to change this power supply because of color, and I can't find similiar with the same ...
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64 views

NodeMCU V3 and MPU6050 strange values

I am new to this platform, so please if I do something against the regular rules please let me know so I can learn. Now my problem: I have a nodeMCU V3 connected to a MPU6050. Using my Arduino Uno I ...
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1answer
74 views

NodeMCU v2 with MH-Z19B CO2 sensor UART read problem

I'm trying to read data from MH-Z19B sensor to NodeMCU v2 board with a simple circuit like this. Some key points, which could be not that obvious from picture: - sensor has separate power supply of ...
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1answer
51 views

Can I connect 220V AC supply to Node MCU (or any arduino)pin D1 and D3 while node MCDU is power off?

Can I connect 220V AC supply to node MCU pin D1 and D3 while node MCDU is power off?
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23 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 ...
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1answer
43 views

Receiving garbage value when sending a Json object from Arduino Uno to NodeMCU using SoftwareSerial

I am trying to send a Json Object from Arduino UNO to NodeMCU using SoftwareSerial. I am using Arduino IDE. I am getting garbage value on Serial monitor of NodeMCU. Tried it with different garbage ...
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1answer
23 views

NodeMCU V2 ESP8266 - Use 5VIN as power for heater of a MQ-9 Sensor

Right now I'm trying to understand how I could (easily) power the heater of my MQ-9 carbon monoxid and gas sensor. Here is the datasheet: http://www.haoyuelectronics.com/Attachment/MQ-9/MQ9.pdf It ...
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1answer
29 views

nodemcu doesnt response in at command mode

I want to sent AT command into node mcu esp8266 module with arduino IDE through serial monitor. I connect the node mcu to arduino uno board in following sequence: RX to pin 2 of arduino TX to pin 3 ...
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1answer
41 views

How does code typed in Arduino IDE runs on a nodemcu?

I actually have a series of questions regarding Nodemcu and esp8266. How does code typed in Arduino IDE run on Nodemcu? What firmware is present on the nodemcu? How do I upload the above firmware on ...
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1answer
28 views

Can stack size be determined by free heap?

i have NodeMCU with es8266 onboard on it. I read heap and stack memory are facing each other and if heap or stack gets full and reachs another strange things happen. So i am wondering if can we use ...
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72 views

How to add a yield before else if?

So I am running my project on a NodeMCU, but I don't know how to let it add a yield in front of an else if. It will give me an error like this: Arduino:1.8.12 (Windows 10), 開發板:"NodeMCU 1.0 (ESP-...
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64 views

Freezing ESP8266 after 4-8h

Build my own 'Artnet to WS2812b Neopixel' boxes for lighting in a club. Working fine. I have 20 stripes with 50 pxls each. One ESP8266(NodeMCU) is feeding 6 stripes, so it gets 2 DMX universes via ...
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1answer
89 views

What is the difference betwen “ESP8266Wifi.h” and “WiFiEsp.h” libraries?

I'll start a project using NodeMCU V3 WiFi Module, which uses esp8266 chip. However, I am undecided as to which library to use. I don't want use a serial bridge with an arduino, I think it is better ...
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1answer
43 views

How to respond dynamically by using File Containing Templates?

We are developing a Web Console and REST API for the NodeMCU V3 ESP8266, using ESPAsyncWebServer. We are facing some difficulties to serve dynamic pages using File Containing Templates! We're unable ...
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59 views

NodeMCU Server side cannot send things to client side - multiple clients attached

I technically need your help, when I am working on my project, I found out that my server-side cannot send data to the client-side, my server-side is made with WiFiServer(80) so it is when my client-...

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