My NODE MCU goes online and then off line every few minutes

Hello, I have two NodeMCUs. One is writing to or controlling the other when certain alarms are detected. The “slave” NodeMCU is ok. It is all the time online, but the “master” Node MCU goes off line every so many minutes and then back on line and then again off line and so on.

I thought it might have been caused by a faulty Node MCU, so I ordered another one. Loaded the sketch again into the new one but it is still doing the same thing.

Any idea what could be causing this? Do i have too many “delays”?

This is the sketch for the “Master” NodeMCU.

With this project, which is easy to implement
we can control and activate an alarm, which sends an email
mentioning that an alarm has been detected.

#define BLYNK_PRINT Serial    //Comment this out to saves space. 
#include <ESP8266WiFi.h>
#include <BlynkSimpleEsp8266.h>
#include <SimpleTimer.h>

// authtoken generated by Blynk
char auth[] = "XXXXXXXXX";

//Wifi connection info.
char ssid[] = "ServerID"; // WIFI server name
char pass[] = "XXXX"; // WIFI password

SimpleTimer timer;

WidgetBridge bridge1(V1);

  // Place the AuthToken of the second Node MCU here

void setup()
  Blynk.begin(auth, ssid, pass);

  // Send email when it connects to Blynk server
  //Default parameters "Email", "subject", "Message to send".  You can also send text to a at&t customer, by using the"","Subject", "Alarm monitoring program re-starting. A power failure could have occurred");
  pinMode(5, INPUT);// pin D1(GPIO5) as input for the Alarm
  //pinMode(4,OUTPUT);// pin D2(GPIO4) as output
  //timer.setInterval(1000L, myTimerEvent); 

void emailtosend()
Serial.println("An Alarm was activated"); //Prints to the serial monitor"", "Alarm Activated", "Please coordinate to make sure someone gets there to fix this issue.");

// The blynk interface has an option to silence the alarm email notifications.  If they have not turned them back on after a certain amount of time, the following sends an email reminding them to turn them back on. 

void emailturnon()
Serial.println("Notifications have been turned off"); //Prints to the serial monitor"", "Notifications are still turned off", "If the issue(s) with the alarms have been resolved, please turn notifications back on");

int pinData = 0;

BLYNK_WRITE(V2) // reading if email notifications have been silenced in the blynk smart phone interface . 
  if (param.asInt())
    pinData = 1;
    pinData = 0;

void Alarma()
  // if alarm is activated it send email.   
  int Sensor = digitalRead(5); // variable to store the state of the alarm
  if (Sensor == 1) // If the switches are activated, then it goes high
   Serial.println("Writing to D1 in Slave NodeMCU"); //Prints to the serial monitor
    bridge1.digitalWrite(5, 1000); // writes in D1 of the slave NodeMCU to also activate the alarm with the slave NodeMCU
     bridge1.digitalWrite(5, 0);    

  if (Sensor == 1) // if the swtiches are activated  
   if (pinData == 0) 
    timer.setTimeout(60000, emailtosend); // send email every 60 seconds when the sensor is activated and when the alarm has not been silenced
  if (pinData == 1)  
    timer.setTimeout(1800000, emailturnon); // send email every 30 minutes when the alarm has been silenced
void loop()
  Alarma();// calls the function to be executed.;

Please format posted code properly, as required in the Welcome Topic…

Blynk - FTFC

Sorry about that.

I have reformatted.


Calling this function directly in the main loop will have it running hundreds of times a second, causing disconnections. Put it on a timer of it’s own.

1 Like

Thank you so much! That makes sense.

I want Alarma() to run as often as possible. Do you think every 10 seconds would be too much?


That should be sufficient, depending on what you need to do. The other thing to watch for is any potential delays or blocking while actually running that function.

Thank you so much Gunner!