My MQ-135 away read 0 when connect to blynk

Solved
1

This code work perfectly fine.

#define BLYNK_PRINT Serial

#define BLYNK_TEMPLATE_ID "TMPL6Im5ueUYs"
#define BLYNK_TEMPLATE_NAME "gas"
#define BLYNK_AUTH_TOKEN "YoSG3piv1DOpv_hW56UAPjNgqtCqZodZ"

#include <WiFi.h>
#include <WiFiClient.h>
#include <BlynkSimpleEsp32.h>


char ssid[ ] = "babe";
char pass[] = "bruhbruh";
#include <MQ135.h>
#include <DHT.h>


#define PIN_MQ135 25 
#define DHTPIN 14 
#define DHTTYPE DHT22 

MQ135 mq135_sensor(PIN_MQ135);
DHT dht(DHTPIN, DHTTYPE);

float temperature, humidity; 
BlynkTimer timer;



void setup() {
  Serial.begin(9600);
  //Blynk.begin(BLYNK_AUTH_TOKEN, ssid, pass);

  dht.begin();

}

void loop() {
  
  humidity = dht.readHumidity();
  temperature = dht.readTemperature();

  // Check if any reads failed and exit early (to try again).
  if (isnan(humidity) || isnan(temperature)) {
    Serial.println(F("Failed to read from DHT sensor!"));
    return;
  }

  float correctedPPM = mq135_sensor.getCorrectedPPM(temperature, humidity);

  Serial.print("\nCorrected PPM: ");
  Serial.print(correctedPPM);
  Serial.println("ppm");

  Serial.print("humidity: ");
  Serial.print(humidity);
  Serial.println("%");

  Serial.print("temperature: ");
  Serial.print(temperature);
  Serial.println("*C");
  Serial.print("Raw MQ135: ");
  Serial.println(analogRead(PIN_MQ135));
  
  // Blynk.virtualWrite(V2, correctedPPM);
  // Blynk.virtualWrite(V0, humidity);
  // Blynk.virtualWrite(V1, temperature);
  
  delay(1000);

}

Output(Serial monitor): Corrected PPM: 97.26ppm
humidity: 74.20%
temperature: 30.40*C
Raw MQ135: 120

but, when blynk added.


#define BLYNK_PRINT Serial

#define BLYNK_TEMPLATE_ID "TMPL6Im5ueUYs"
#define BLYNK_TEMPLATE_NAME "gas"
#define BLYNK_AUTH_TOKEN "YoSG3piv1DOpv_hW56UAPjNgqtCqZodZ"

#include <WiFi.h>
#include <WiFiClient.h>
#include <BlynkSimpleEsp32.h>


char ssid[] = "babe";
char pass[] = "bruhbruh";
#include <MQ135.h>
#include <DHT.h>


#define PIN_MQ135 25 
#define DHTPIN 14 
#define DHTTYPE DHT22 

MQ135 mq135_sensor(PIN_MQ135);
DHT dht(DHTPIN, DHTTYPE);

float temperature, humidity; 
BlynkTimer timer;



void setup() {
  Serial.begin(9600);
  Blynk.begin(BLYNK_AUTH_TOKEN, ssid, pass);

  dht.begin();

}

void loop() {
  
  humidity = dht.readHumidity();
  temperature = dht.readTemperature();

  // Check if any reads failed and exit early (to try again).
  if (isnan(humidity) || isnan(temperature)) {
    Serial.println(F("Failed to read from DHT sensor!"));
    return;
  }

  float correctedPPM = mq135_sensor.getCorrectedPPM(temperature, humidity);

  Serial.print("\nCorrected PPM: ");
  Serial.print(correctedPPM);
  Serial.println("ppm");

  Serial.print("humidity: ");
  Serial.print(humidity);
  Serial.println("%");

  Serial.print("temperature: ");
  Serial.print(temperature);
  Serial.println("*C");
  Serial.print("Raw MQ135: ");
  Serial.println(analogRead(PIN_MQ135));
  
  // Blynk.virtualWrite(V2, correctedPPM);
  // Blynk.virtualWrite(V0, humidity);
  // Blynk.virtualWrite(V1, temperature);
  
  delay(1000);

}

I just uncomment the Blynk.begin(BLYNK_AUTH_TOKEN, ssid, pass); and my mq135 stop send any signal.
The output look like this(Serial monitor):
Corrected PPM: 0.00ppm
humidity: 74.30%
temperature: 30.40*C
Raw MQ135: 0

I don’t know why mq135 can’t send any signal back to my esp32_wrover
Help.

2

@FlyingS Please edit your post, using the pencil icon at the bottom, and add triple backticks at the beginning and end of your code so that it displays correctly.
Triple backticks look like this:
```

Copy and paste these if you can’t find the correct symbol on your keyboard.

Also, snippets of code are no use to us in situations like this, we need to see your full sketch.

Pete.

3

I already edit my post. Also I need to fix this reading problem before going further with project. So, this is my full sketch for now.

4

GPIO25 is connected to ADC2, which can’t be used at the same time as WiFi.
Read this link and choose an ADC1 pin instead…

And, while you’re reading that link you need to study the “keep your void loop clean” info too. You can’t use delays in your void loop when you’re using Blynk, you need to use BlynkTimer instead.

Pete.

1 Like
5

Thank for your help, it work now.

2 Likes