Sampling rate for sensor when combined

[moskovskiy82]

I have combined Relay and MQ+DHT

What i would like to do is set a sampling period for a sensor at say 5 seconds.
Is this supposed to be done with millis? Can somebody help with the code sample?

Let's presume for MQ as an exxample

float mq_reading = analogRead(MQ_Pin);
  if (isnan(mq_reading)) 
  {
      Serial.println("Failed mq_reading");
  } 
  else if (mq_reading != last_mq_reading) 
  {
    last_mq_reading = mq_reading;
    gw.send(msgMQ.set(mq_reading, 1));
    Serial.print("MQ: ");
    Serial.println(mq_reading);  
  }
}```

[sundberg84]

Hi!

Yes - im using millis() if i dont sleep the node (which seems overkill if you only wants 5 seconds).
What you need to find out if you sensors have the possibility to read that fast. For the dht i think thats about when you just run the normal reading without delay in the loop.

[moskovskiy82]

Can you give a code example? Currently it reports every second almost

[sundberg84]

long previousMillis = 0;        // will store last time something happened
long interval = 5000;           // interval at which to blink (milliseconds)

void loop()
{
 unsigned long currentMillis = millis();
 
  if(currentMillis - previousMillis > interval) {
    // save the last time something happened
    previousMillis = currentMillis;   
 
Insert your code here...

  }
}

Note millis() does not work if you are using gw.sleep()