DHT22 Garbage Value

Need Help With My Project
1

Hi, can anyone help figure what is wrong? constantly getting these garbage values despite changing the variable types
image

#include <ESP8266WiFi.h>
#include <BlynkSimpleEsp8266.h>
#include "DHT.h"
#define DHTTYPE DHT22
#define dht_dpin D4
DHT dht(dht_dpin, DHTTYPE);

//All variables with their data types
int temp2, setpoint2;

//Your Auth Token
char auth[] = "-";

// Your WiFi credentials.
// Set password to "" for open networks.
char ssid[] = "SINGTEL-FA54";
char pass[] = "zucheohaen";

WidgetBridge bridge1(V1);

BLYNK_CONNECTED() {
  // Place the AuthToken of the Device -1 here
  bridge1.setAuthToken("-");
}

BLYNK_WRITE(V12)
{
  temp2 = param.asFloat();
}



BLYNK_WRITE(V22)
{
  setpoint2 = param.asFloat();
}


void setup()
{
  Blynk.begin(auth, ssid, pass);
  dht.begin();
  Serial.begin(9600);
}

void loop()
{
  Blynk.run();

  temp2 = dht.readTemperature();
  Blynk.virtualWrite(V12, temp2);
  //bridge1.virtualWrite(V12, temp2);
  //bridge1.virtualWrite(V22, setpoint2);

}
2

Put this in a timed function that’s called no more tan once every 5 seconds.
Use a float variable type.

I don’t understand why you’re assigning a value to temp2 from the widget V12 and from the DHT22.

Pete.

3

I have tried the following code but no value appeared. changed my wemos, sensor and cable but still does not work.

#include <ESP8266WiFi.h>
#include <BlynkSimpleEsp8266.h>
#include <DHT.h>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = "-";

// Your WiFi credentials.
// Set password to "" for open networks.
char ssid[] = "SINGTEL-FA54";
char pass[] = "zucheohaen";

#define DHTPIN D4          // What digital pin we're connected to
#define DHTTYPE DHT22   // DHT 22, AM2302, AM2321

DHT dht(DHTPIN, DHTTYPE);
BlynkTimer timer;

// This function sends Arduino's up time every second to Virtual Pin (5).
// In the app, Widget's reading frequency should be set to PUSH. This means
// that you define how often to send data to Blynk App.
void sendSensor()
{
  float t = dht.readTemperature(); // or dht.readTemperature(true) for Fahrenheit

  if (isnan(t)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }
  Blynk.virtualWrite(V12, t);
}

void setup()
{
  Serial.begin(9600);

  Blynk.begin(auth, ssid, pass);
  dht.begin();

  timer.setInterval(1000L, sendSensor);
}

void loop()
{
  Blynk.run();
  timer.run();
}
4

What does your serial monitor show?

Pete.

5

Also as Pete pointed out set your timer to min 3 seconds. Preferably 5.

6

It says fail to read sensor but I’m not too sure why. As mentioned, I have changed all components for multiple times. My device is online on Blynk App as well.

I have been trying to troubleshoot this issue for weeks… temperature on blynk app is either garbage value or no reading.

7

Add some serial print lines to see exactly what nan (not a number) values the sensor is giving.
Check that your DHT library is up to date, and maybe delete it and install a different one instead.

Pin D4 (GPIO2) isn’t a great choice of pin either:

Pete.

8

I have gotten the nan value multiple times but the serial monitor still reads failed to read sensor.

I have also tried alternating the pins of the WeMos D1 mini board.

9

You only get the “failed to read…” message if the value returned by the sensor is not a number.
I was suggesting that you add some serial print messages to see what was being returned.

And what about the suggestion to change the library?

Pete.