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Questions tagged [nodemcu]

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

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Getting the error calibrate' was not declared in this scope

#include <LiquidCrystal_I2C.h> #include <Wire.h> #include <ESP8266WiFi.h> LiquidCrystal_I2C lcd(0x27, 16, 2); #define DT D2 #define SCK D1 #define sw 9 long sample=0; float val=0; ...
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26 views

What is the Lifespan of NodeMCU 12-E? [on hold]

i am using the NodeMCU in a homeautomation project, how much does the NodeMCU last, and what about its efficiency? thanks in advance
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14 views

NodeMCU with HC-SR04 ultrasonic sensor

How can I interface an ultrasonic sensor with a MCU with 3.3 V GPIO like the NodeMCU? I tried powering the sensor with both 5 V and 3.3 V from the MCU. Both failed to show any results as the distance ...
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2answers
21 views

Using NodeMCU D8 (GPIO15), D4 (GPIO2) and D3 (GPIO0) pins

I am using a NodeMCU board and have already used 6 digital pins as output for interfacing with the LCD. I intend to use 2 more digital pins, one as input and other as output for interfacing an ...
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1answer
33 views

Using a water sensor with a NodeMCU make it less sensitive?

I'm trying to digitalRead from a water sensor (the one in the picture) using NodeMCU v3,when I try the sensor with an Arduino board it works fine, but when I try it with an ESP8266 NodeMCU v3 it ...
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1answer
26 views

WS2812B only works while I measure the voltage

I'm going crazy, there is clearly something I'm missing here. I have a NodeMCU V3.0 and a 5V LED strip WS2812B with 10 diodes. I tested this first with a 5V 0.3A power supply, only powering 3 diodes, ...
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12 views

NodeMCU with JHD162A LCD issue

I have uploaded a program to NodeMCU , to print "hello, world" on JHD162A 16x2 LCD module. But the text doesn't appear on the lcd display. Instead just black blocks appear on the first row on the LCD. ...
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1answer
42 views

Possible to connect 3 MPU9250 to Node MCU without multiplixer?

Is the idea of connecting AD0 pins of MPU9250 is still valid like the 2nd answer of this question? - How to change i2c address for mpu9250? I have connected 2 sensor as test. SCL & SDA of both ...
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1answer
32 views

Arduino program to scan two different rfid cards in same program ? Im using nodemcu- esp8266 , rc522 reader and Firebase

/*My project is a Library management system using rfid cards. Im trying to generate a code wherein User first scan a book and then the record will be pushed in Issued_Books table in Firebase . Then ...
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21 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/...
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How to connect 3 MPU9250 to Node Mcu together?

I don't know how to connect 3 MPU9250 together on Node Mcu. There is not much information available. I am using bolder flight library for imu sensor - https://github.com/bolderflight/MPU9250 Can ...
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1answer
22 views

Not able to convert String to Integer when receiving data from pubnub?

I did managed to upload mpu9250 sensor data on PubNub and nodeMcu but not able to use the received data to control servo Look at the Port reading and see that servo angle is still showing '0' Code:-...
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1answer
19 views

How to upload sensor data on pubnub IOT with JSON Format?

I am trying to send MPU9250 sensor data to Pubnub IOT platform using node mcu, but not able to do it since the sensor data is not in JSON format. I know about publishing string but don't know about ...
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1answer
38 views

NodeMCU with NEO GPS and ultrasonic sensor HR SC04 [on hold]

I am connecting a NEO GPS 6M and an ultrasonic sensor to NodeMCU. When I connect individual components separately it's working, but when I combine both of them, the ultrasonic sensor is not working ...
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1answer
52 views

How to interface MPU9250 and NodeMcu?

I am trying to send MPU sensor data to Pubnub IOT platform but not able to do it since there is some unknown problem. There is no error in code but following issue pops up in com port:- It looks like ...
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1answer
111 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 ...
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1answer
27 views

Can't flash ESP8266 anymore (NodeMCU)

So I've been happily making away with these nodeMCU boards now for a while but I came across a strange issue when updating some code on my board.The problem was that I couldn't flash anymore with ...
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52 views

Why is this Code not working with Esp8266 when it worked perfectly with Arduino Uno?

I'm making an attendance System using an RFID scanner, scanning RFID Card & saving Data in Excel. When I used this code with Arduino Uno (by changing #define SS_PIN 12 and#define RST_PIN 9) it ...
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18 views

NodeMCU V3 - Troubleshooting basic TMP36 circuit

If I follow this example using my Arduino Uno https://learn.adafruit.com/tmp36-temperature-sensor/using-a-temp-sensor (using the 3.3V code example at the bottom of the page), I get reasonable ...
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38 views

Understanding flashing with bash in Ubuntu

I am following the instruction from this DIY tutorial to set up the firmware for my dust sensor on Arduino board (NodeMCU): https://luftdaten.info/en/construction-manual/#feinstaubsensor-konfiguration ...
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26 views

Serial communication problem NodeMCU

this is my first post here. Before I ask you my problem, I'm sorry if I'm wrong to write but my English is bad. So, my problem is this: I'm developing a "client-server" system with serial ...
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1answer
50 views

NodeMCU display temperature and control LED from an autorefresh web page

I'm totaly new to Arduino, I'm using ESP2866 NodeMCU and dht22 to display temperature and humidity in a web page, it is autorefresh (using AJAX) and it works perfectly, I wanted to add 2 buttons to it ...
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21 views

Voltage to keep my board safe

I have recently made a home automation system using node mcu and relay module and i am powering both together using my 5V ,2A dc adapter and i am scared that if I'll keep using it for very long hours ...
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1answer
72 views

Transmit/Receive data Nodemcu(V3) + Bluetooth Module HC-05

I am trying to communicate with the HC-05 Bluetooth module for quite long time now, but with no success. I am using the Nodemcu(V3) ESP8266 module. I connect the HC-05 to Nodemcu in following ...
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25 views

RF Rx with NodeMCU error

I am using RF Tx with Arduino Uno and Rx with NodeMCU. I use RF switch library. At the recipient side if I use an Arduino Uno MCU. I can receive the output, but with NodeMCU I have a blank serial ...
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1answer
27 views

Connecting NodeMCU through internet [closed]

I have a NodeMCU and a website (free website domain provided by http://www.hpage.com) and I have to send and receive some data (suppose a 8bit number) from the website to the NodeMCU via internet. The ...
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1answer
70 views

NodeMCU Ping working on one but not another

Update 2: Have tested by pinging various devices on different subnets / vlans and did a pcap on the wifi AP I can see the icmp requests going through for each request except for ones on the 4.x subnet,...
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2answers
114 views

What is the voltage between Vin & GND?

I have NodeMCU ESP8266N Lolin V3, my 5V relay is powered from Vin of the NodeMCU. The NodeMCU is powered from 5V USB. My difficulty is when I measure voltage between Vin & GND, it is of 1.9V, but ...
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1answer
30 views

Power Arduino Mega ESP85266

Is it possible to Power a Arduino Mega 2560 and a NodeMCU V2 ESP8266 ESP-12E from a single 9V Block? What would be the best solution? Can i power the ESP8266 directly via the Arduino Mega 5V output? ...
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31 views

How to trigger NodeMCU sketch from Arduino Leonardo Micro Pro?

So this is probably a very simple question. I have my NodeMCU set up and working where it connects to wifi and sends a push notification. Currently it does that automatically when connected to power. ...
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44 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 ...
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58 views

HTTP PUT method on NodeMCU/ESP8266

I've been trying to send a put request from my esp8266 for a while not but I can't figure out why it doesn't work and there are barely any posts about put requests online I keep getting errors around ...
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36 views

Can anyone explain this?

starting app without reboot espcomm_send_command: sending command header espcomm_send_command: sending command payload espcomm_send_command: receiving 2 bytes of data closing bootloader ...
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1answer
38 views

Error - invalid conversion from 'char' to 'const char*', Not able to connect on pubnub server using node mcu [duplicate]

I have node mcu with ESP8266 wifi module. When i am trying to upload an example code then its not working. This is the Error:- inline PubSubClient* PubNub::subscribe(const char* channel, int ...
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61 views

Nodemcu + GSM IOT-GA6

I've connected my NodeMCU to GSM module using GND, RX and TX. I use At Comand Tester. When I try to get sim status or something I get error for example: Unable to get Sim status. Only AT comand ...
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1answer
52 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/...
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24 views

I want to connect my NodeMcu v3 to gsm

I have a problem with connecting my NodeMcu to gsm. I have bought GSM module but I have sim code on card which I can't and that is the problem because I've found some libraries but there are no ...
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1answer
87 views

How to find the MAC address using NodeMCU when connecting to WiFi?

I am new to using NodeMCU and IOT. I am testing the NodeMCU (ESP8266) so that I can connect with pubnub server. Have taken code from github but there is error saying 'mac was not declared in this ...
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1answer
260 views

Deep Sleep NodeMCU with Door Sensor

I have a very simple code of door sensor (magnetic) which gives results in 1 & 0 format. But I want to run the NodeMCU only when a door is open or close. Rest of time I want to keep it in deep ...
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1answer
71 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 ...
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1answer
61 views

The code is working fine with Arduino Uno but not with NodeMCU

I uploaded program MPU6050_DMP6_Multiple.ino (https://github.com/eadf/MPU6050_DMP6_Multiple/blob/master/MPU6050_DMP6_Multiple.ino) to Arduino Uno and it works fine. When I upload the very same code to ...
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1answer
68 views

Detect power interruption on NodeMCU

Im using a 5v 1A power supply and connected to VIN pin on the NodeMCU. I also use 18650 battery to keep NodeMCU running in case the power supply shuts off due to power interruption. I'm planning to ...
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34 views

Garbage output/ not running at start up nodemcu

I have a nodemcu acting as a thermostat home office. The wall heating element is controlled with a solid state relay on D2. If i have it connected, I cannot program the board from the arduino ide. I ...
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58 views

NodeMCU with digital sound sensor - Can't find examples or good documentation

I'm very new to this world, and trying to hack one of my first projects have proven hard without solid documentation or examples to copy like I usually do. I've got a https://www.gearbest.com/...
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1answer
32 views

Help to delimit and read specific contents of incoming HTTP string

I am sending strings to an Esp8266 via web browser. The below code returns the following in serial monitor if I send in browser: Send from browser to esp8266 - http://192.168.1.220/s1s2s3s4s5d1 ...
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1answer
26 views

Why is this failing after 3 iterations?

I simply cannot figure this out, why is this failing after 3 iterations? Other than that, what better way is there to do this? Thanks! #define rotary_encoder_topic "/rotary/encoder" #define ...
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1answer
51 views

Can't extract basic data using ThingspeakHTTP

I don't know anything about HTML, but I want to extract the % probability of the Northern lights being visible from this webpage http://aurorawatch.ca/. I entered this into the URL field, and selected ...
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1answer
139 views

Taking String Input from NodeMCU Webpage and Printing it on Serial Monitor

I've started working with NodeMCU recently. I've very little knowledge about this device and how a website works. I'm trying to take a long string input from a website hosted by NodeMCU, store it on a ...
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1answer
59 views

Addressable RGB LED Strip

I am looking to create an addressable RGB LED strip circuit with my NodeMCU v3 Wi-Fi. I am looking at a strip of 150 RGB LEDs, 5 meters long, so 30 LED/m. But I am only going to use about 50 LEDs for ...
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39 views

Does NodeMCU have some protection against wrong connections that could kill a computer USB?

I know some computer USB could handle some bad connection (by blocking the port, which need to reboot the computer). But I wonder if a NodeMCU 8266 offers some protection.