Comparing Numeric Input with Variable or Vritual Pin (data from DS18B20 temperature sensor)

Need Help With My Project
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1

Hi,

I’m newbby with Arduino and Blynk. I’m triying to do an aquatic cooler wih a function that could turn on when the temperature of the water is less than a seteable parameter (It’s a Numeric Input).

I tried to use two functions but without lucky. :confused: Please help me.

• NodeMCU with WiFi
• Android version 10
• Blynk server
• Blynk Library v0.6.1

#include <Blynk.h>
#include <OneWire.h>
#include <SimpleTimer.h>
#include <ESP8266WiFi.h>
#include <DallasTemperature.h>
#include <BlynkSimpleEsp8266.h>

BlynkTimer timer; // Declaración del timer

OneWire oneWire(4);
DallasTemperature sensors(&oneWire);

char auth[] = "***";
const char ssid[] = "***";
const char pass[] = "***";

const int pinRele = 14;

String str;
String str1;

int temperature;  
         
void setup(){
  Serial.begin(9600);
  Blynk.begin(auth, ssid, pass);

  sensors.begin();                        // Starts the DS18B20 sensor(s).
  sensors.setResolution(10);              

  timer.setInterval(2000L, sendTemps);    // Temperature sensor read interval. 2000 (ms) = 2 seconds.
  timer.setInterval(2000L, enfriar);    // Temperature sensor read interval. 2000 (ms) = 2 seconds.

  pinMode(4, INPUT);

  pinMode(14, OUTPUT);
  digitalWrite(14, HIGH); // relay is HIGH triggering
  
}

void sendTemps(){
  sensors.requestTemperatures();                  // Polls the sensors.
  temperature = sensors.getTempCByIndex(0);   // Stores temperature. Change to getTempCByIndex(0) for celcius.
  Blynk.virtualWrite(V0, temperature);         // Send temperature to Blynk app virtual pin 1.

}

BLYNK_CONNECTED(){
  // relay is HIGH triggering   
  if (digitalRead(14) == 0) Blynk.virtualWrite(V6, digitalRead(14));
  else Blynk.syncVirtual(V6);
}

//Test 1
BLYNK_WRITE(V24){
  int pinValue = param.asInt(); // assigning incoming value from pin V1 to a variable
  if(pinValue > temperature){
    digitalWrite(pinRele, HIGH);
  }else{
    // do nothing   
  }
}

//Test 2
void enfriar(){
  // Encender enfriador
  while( digitalRead(V24) > V0){
    digitalWrite( pinRele, HIGH);
  }
}

void loop(){
  Blynk.run();        // Ejecuta la magia de Blynk
  timer.run();        // Ejecuta el timer cada seg
  
}

Thanks,

Gonzalo

2

Your BLYNK_WRITE(V24) function needs to be assigning the temperature setpoint to a global variable (not local as it is at the moment) and nothing more.

Your enfriar() function shouldn’t be using a while statement.
Instead it should have an if statement which compares the temperature to the setpoint and takes the appropriate action (turns a relay on else turns it off for example).

Pete.

3

In this case I would suggest you should get your project working as you like on ARDUINO only first . . . then when it is doing what you want, only then add the Blynk code

This will make your troubleshooting much simpler given you are new to this.
billd

4

Really thank you Pete, your hel was very usefull!