Connection to Blynk


I have Problem to connect to Blynk when I have this commands.

oneWire.h, version 2.3.7
DallasTemperature.h, version 3.9.0

This is only a test program to se if it works.
I have a program which work well when connecting to Blynk, when I insert the following it does not connect to Blynk.
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);

It only comes up with connecting to “Connecting to Altiboxxxxxx” and nothing more is happening.

Have tested the DS18B20 connection and that works when not connecting to Blynk.

#define BLYNK_PRINT Serial
#include <WiFi.h>
#include <WiFiClient.h>
#include <BlynkSimpleEsp32.h>

#include <OneWire.h>
#include <DallasTemperature.h> 
#define ONE_WIRE_BUS 4          // Your ESP32 pin D4)
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = "k6jj6ZbDT3m75rckz1BAVyn3g3VrLske";

// Your WiFi credentials.
// Set password to "" for open networks.
char ssid[] = "Altiboxxxxxx";
char pass[] = "xxxxxxxx";

BlynkTimer timer;

float roomTemperature;            // Room temperature in F

void setup()
  // Debug console

  //Blynk.begin(auth, ssid, pass);
  // You can also specify server:
  //Blynk.begin(auth, ssid, pass, "", 80);
  Blynk.begin(auth, ssid, pass, IPAddress(192,168,1,100), 8080);

  sensors.begin();                        // Starts the DS18B20 sensor(s).
  sensors.setResolution(10);              // More on resolution:

  timer.setInterval(5000L, sendTemps);    

void loop()
  // You can inject your own code or combine it with other sketches.
  // Check other examples on how to communicate with Blynk. Remember
  // to avoid delay() function!
void sendTemps()
  sensors.requestTemperatures();                  // Polls the sensors.
  roomTemperature = sensors.getTempCByIndex(0);   // Stores temperature. Change to getTempCByIndex(0) for celcius.
  Blynk.virtualWrite(1, roomTemperature);         // Send temperature to Blynk app virtual pin 1.
  Serial.print("Temp :");
  Serial.println(roomTemperature, 2);

So this sketch is for use with Blynk legacy local server.
It’s always a good idea to state that at the beginning of your post, as it’s a very rare situation now, and it saves people jumping-in with comments about missing template IDs etc.

A few questions…

  1. what version of local server are you running?
  2. what Blynk library version are you using?
  3. is your device connected to the same network as your local server?
  4. does your local server log show an attempted connection from your device? If so, what refusal reason does it show?
  5. what version of the ESP32 core do you have installed?



Thanks for the answer.

  1. Where di I find that?
  2. The Blynk library installed is 1.3.2
  3. Device is connected to the same network.
  4. There is NO error on the serial monitor or when i compiles or during downloading to
    the ESP32.

As I mention in my first mail, everything is working fine before I compile withe those 2 lines
OneWire oneWire(oneWireBus);
DallasTemperature sensors(&oneWire);

No errors during compiling.

Stops here
char auth = “k6jj6ZbDT3m7xxxxxxxxVyn3g3VrLske”; // replace this with your auth token
char ssid = “Altiboxxxxxxx”; // replace this with your wifi name (SSID)
char pass = “xxxxxx”; // replace this with your wifi password
bool Connected2Blynk = false;

Nothing is happening after that on the serial monitor.


  1. unless you’ve renamed it, the version number is contained in the name of your local server .jar file, something like server-0.41.xx.jar

  2. if you’re using Blynk Legacy with a local server then you should be running version 0.6.1 of the Blynk C++ library.

  3. I was asking about your local server .log files, not your serial monitor

  4. your response doesn’t answer my question.

What sort of device are you running your local server on?



I’m not an expert on this, but I,m using Blynk because this w
as the only one I found I could use everywhere without any local server.

On my ESP32 I connect to the local Wifi I have in my house, program the ESP on a windows PC.

Then I can connect to the Blynk app version 3.6.6 (1), server (fra

Using to display on the PC.

Tested this outside the range of my home WiFi.

Sorry, if this is not what you are asking for.


So, your intention is NOT to use Blynk legacy local server, but to use Blynk IoT connected to the server?

In that case, you have two big problems with the sketch you posted at the beginning of this topic….

Issue 1
You are instructing the sketch to connect to a local server on your own network, at IP address….

Issue 2
Your sketch is missing the BLYNK_TEMPLATE_ID and BLYNK_TEMPLATE_NAME declarations from the beginning of your sketch.



This is correct.

Below is a code that works very vell. as long I remove the lines for the DS18B20 sensor.
( I have tested this on a program, not connecting to Blynk and it works well).
I have a relay connect on V8 , so when I press the OFF button in the app the relay close.
Also I want to connect a magnetic switch and se if the garage port is open or closed. Want to have the widgets LED (V9) to be green or red depending on the status of the port.
The last ting is not working yet.
If I do not get the ds18B20 to work I have to find another sensor.
(Going to use a SHT-21 sensor instead of the BME280)

Also I need to do some cleanup in the program.

#define BLYNK_TEMPLATE_NAME "Weather Station"
#define BLYNK_GREEN     "#23C48E"
#define BLYNK_RED       "#D3435C"
//#define MagSwitch_PIN 32
#define SD_CS 5
/* Comment this out to disable prints and save space */
#define BLYNK_PRINT Serial

#include <WiFi.h>             // Library for the WiFi interface
#include <RTClib.h>           // Library for the DS3231 RTC module
#include <Wire.h>             // Library for the I2C interface
#include <WiFiClient.h>
#include <BlynkSimpleEsp32.h>
#include "Arduino.h"
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>
#include <LiquidCrystal_I2C.h>  // Library for the 12C 20x4 LCD module
// #include "FS.h"                 // Libraries for the microSD card
#include "SD.h"                 // Libraries for the microSD card
#include <SPI.h>                // Libraries for the microSD card
#include <OneWire.h>            // Libraries for the DS18B20
#include <DallasTemperature.h>  // Libraries for the DS18B20
//#include "DHT.h"
//#include "SI114X.h"
//#include "BMP085.h"

// Save reading number on RTC memory
RTC_DATA_ATTR int readingID = 0;   //
File myFile;

Adafruit_BME280 bme; // I2C 0x76
BlynkTimer timer;

// const int CS = 5;      // SD card
const int oneWireBus = 4; // GPIO where the DS18B20 is connected to
int pin = 26;             // Relay
int MagSwitch = 32;
WidgetLED led1(V9);   // Virutal pin V9 for Widget LED

//OneWire oneWire(oneWireBus);     // Setup a oneWire instance to communicate with a OneWire device
//DallasTemperature sensors(&oneWire);  // Pass our oneWire reference to Dallas Temperature sensor

// float temperature; // parameters
// float DallastemperatureC;
// float humidity;
// float pressure;
// float mbar;
// float altitude;
// float uv;
// float visible;
// float ir;

LiquidCrystal_I2C lcd(0x27, 20, 4); // create LCD with I2C address 0x27, 20 characters per line, 4 lines
RTC_DS3231 rtc;                     // create rtc for the DS3231 RTC moduke, address is fixed at 0x57

//SI114X SI1145 = SI114X(); // initialise sunlight sensor
//BMP085 myBarometer; // initialise pressure sensor

char auth[] = "xxxxxxxxxxxxxxxxxx"; // replace this with your auth token
char ssid[] = "xxxxxxxxxxxx"; // replace this with your wifi name (SSID)
char pass[] = "xxxxxxxxxxx"; // replace this with your wifi password
bool Connected2Blynk = false;

//DHT dht(DHTPIN, DHTTYPE); // initialise dht sensor

/*void sendSensor() // function to read sensor values and send them to Blynk
  humidity = dht.readHumidity();
  temperature = dht.readTemperature();
  if (isnan(humidity) || isnan(temperature))
    Serial.println("Failed to read from DHT sensor!");

void setup()
  //rtc.begin ();         // Initialize the RTC 24H format
  lcd.init();           // Initialize the LCD
  //sensors.begin(); // Start the DS18B20 sensor
  Serial.println("ESP32_WS_Relay_BLYNK 221223");
  /*Serial.println("Beginning Si1145!");
    while (!SI1145.Begin())
    Serial.println("Si1145 is not ready!");
    Serial.println("Si1145 is ready!");

  // Initializ the RTC
  if (! rtc.begin()) {
    Serial.println("Couldn't find RTC");
    while (1);

  // Initialize SD card (F("save SRAM memory by moving the constant string from SRAM to FLASH memory"))
  Serial.println(F("Initializing SD card..."));
  if (!SD.begin(SD_CS)) {
    Serial.println(F("Error, SD Initialization Failed!"));
    while (1);
  Serial.println(F("SD card INITIALIZED."));

  if ( SD.exists("/Log.txt") == 0) { // test if file with name 'Log.txt' already exists
    Serial.println(F("Log.txt doesn't exist. Creating Log.txt file..."));
    // create a new file by opening a new file and immediately close it
    File myFile ="/Log.txt", FILE_WRITE);
  // recheck if file is created or not
  if ( SD.exists("/Log.txt"))
    Serial.println(F("Log.txt exists on SD Card."));
    Serial.println(F("Log.txt doesn't exist on SD Card."));

  File myFile ="/Log.txt", FILE_WRITE);   // create (&open) file Log.txt
  if (myFile) {
    // if the file opened okay, write to it:
    // write some texts to 'Log.txt' file
    myFile.println("Reading ID  |   DATE    |    TIME  ; TEMPERATURE ; HUMIDITY ; AVERAGE Hum ; DewPoint ; Temp. box");
    myFile.println("            (dd-mm-yyyy)|(hh:mm:ss);     degC    ;     %    ;      %      ;   degC   ;   degC");
    myFile.close();   // close the file
    Serial.println("Success, data written to Log.txt");
  } else {
    Serial.println("Error, couldn't not open Log.txt");

  pinMode(pin, OUTPUT); // Initialise digital pin 26 as an output pin

  pinMode(MagSwitch, INPUT);  // Where Magnetic Switch is connected 32 as input pin


  Blynk.begin(auth, ssid, pass);
  Serial.print("RSSI: ");

  timer.setInterval(2000L, getBME280Readings); // sendSensor function will run every 2000 milliseconds
  timer.setInterval(3000L, PortStatus); // Check if Magnetic Switch is open or closed
  timer.setInterval(10000L, ESP32TimeAndDate); // Print ESP32 Time and date
  timer.setInterval(300000L, LogDateAndTime);  // Save to SD card every hour 1t=3600000

  lcd.init();           // Initialize the LCD
  lcd.setCursor(1, 0);
  lcd.print("IP: ");
  lcd.setCursor(1, 0);
  lcd.print("IP: ");
  lcd.setCursor(1, 1);
  lcd.print("RSSI: ");
  // lcd.setCursor(1, 2);
  // lcd.print("Temp: ");
  // lcd.print(bme.readTemperature(), 2);
  // lcd.setCursor(9, 2);
  // lcd.print("\xC2\xB0");
  // lcd.print("C");

  bool status;

  // default settings
  // (you can also pass in a Wire library object like &Wire2)
  status = bme.begin(0x76);  // I2C Adress of BME280
  if (!status) {
    Serial.println("Could not detect a BME280 sensor, Fix wiring Connections!");
    while (1);

  int pinValue = param.asInt(); // assigning incoming value from pin V8 to a variable
  Serial.print("V8 Buttom value is: ");
  digitalWrite(pin, HIGH); // Set digital pin 26 HIGH
  delay (500);
  digitalWrite(pin, LOW);  // Set digital pin 26 LOW

void LogDateAndTime () {
  String dataString = "";

  DateTime now =;

  if ( < 10) {
    dataString += String("0");
  dataString += String(, DEC);
  dataString += ".";
  if (now.month() < 10) {
    dataString += String("0");
  dataString += String(now.month(), DEC);
  dataString += ".";
  dataString += String(now.year(), DEC);
  dataString += " ";
  if (now.hour() < 10) {
    dataString += String("0");
  dataString += String(now.hour(), DEC);
  dataString += ":";
  if (now.minute() < 10) {
    dataString += String("0");
  dataString += String(now.minute(), DEC);
  dataString += ":";
  if (now.second() < 10) {
    dataString += String("0");
  dataString += String(now.second(), DEC);
  dataString += ";";
  dataString += readingID;
  dataString += ";";
  dataString += String(bme.readTemperature(), 2);
  dataString += ";";
  //dataString += String(sensors.getTempCByIndex(0), 2);
  //dataString += ";";

  Serial.print (F("DataString "));
  File myFile ="/Log.txt", FILE_WRITE);   // open file Log.txt

void ESP32TimeAndDate () {
  DateTime now =;
  Serial.print("ESP32 RTC Date Time: ");
  Serial.print(, DEC);
  Serial.print(now.month(), DEC);
  Serial.print(now.year(), DEC);
  Serial.print ("  ");
  Serial.print(now.hour(), DEC);
  Serial.print(now.minute(), DEC);
  Serial.println(now.second(), DEC);

  delay(1000); // delay 1 seconds

void getBME280Readings()
  float temperature = bme.readTemperature();
  float pressure = bme.readPressure() / 100.0F;
  float humidity = bme.readHumidity();
  //float altitude = bme.readAltitude(SEALEVELPRESSURE_HPA);
  if (isnan(humidity) || isnan(temperature))
    Serial.println("Failed to read from BME280 sensor!");
  double DewPoint = (243.04 * (log(humidity / 100) + (17.625 * temperature) / (243.04 + temperature ))) / (17.625 - log(humidity / 100) - ((17.625 * temperature ) / (243.04 + temperature )));
  //float DallastemperatureC  = sensors.getTempCByIndex(0);

  //pressure = myBarometer.bmp085GetPressure(myBarometer.bmp085ReadUP()); // read pressure value in pascals
  //mbar = pressure / 100; // convert millibar to pascals
  //visible = SI1145.ReadVisible(); // visible radiation
  //ir = SI1145.ReadIR(); // IR radiation
  //uv = SI1145.ReadUV(); // UV index

  Blynk.virtualWrite(V0, temperature); // send all the values to their respective virtual pins
  Blynk.virtualWrite(V1, pressure);
  Blynk.virtualWrite(V2, humidity);
  Blynk.virtualWrite(V3, DewPoint);
  //Blynk.virtualWrite(V4, DallastemperatureC);
  //Blynk.virtualWrite (V4, altitude);
  //Blynk.virtualWrite(V5, visible);
  //Blynk.virtualWrite(V6, ir);
  //Blynk.virtualWrite(V7, uv);

// **********************************

void PortStatus()
  int value = digitalRead(MagSwitch);
  if (value == HIGH) {
    //Serial.println("Button is pressed");
    //BLYNK_WRITE (V9)
    //Blynk.setProperty(V9, "color", "#23C48E");  // BLYNK GREEN
    //Blynk.virtualWrite(V9, "color", "#23C48E");
    //Blynk.notify("Switch Pressed"); // This notification will be sent to Blynk App,,notification%20will%20be%20sent%20to%20Blynk%20App%20%7D
  else {
    //Serial.println("Button is not pressed");
    //Blynk.setProperty(V9, "color",  "#D3435C");  // BLYNK RED
// *******************************

// ***********CheckBlynk**********
void CheckBlynk()
  if (!Blynk.connected())
    Serial.println("Restarting ESP32 ... ");
    Serial.print("RSSI: ");
    // Blynk.connect();
// ******END CheckBlynk**********

void loop()

  // PortStatus();
  // ESP32TimeAndDate();;;


Hi Pete

Do you have a solution on this problem?
As I mention earlier the program I have attached in the previous answer works without any problem when I remove the 2 lines for the DS18B20.


TBH I gave up after realising that you’d posted irrelevant code which you said worked fine, but couldn’t have done unless you were running a legacy local server (which you aren’t).



Sorry for that you think is a irrelevant code.
Do not see what is irrelevant ? and I’m disappointed that you did not answer after my last post.
It is clear there is a problem with the Dallas sensor with blynk.
This is the last time I post something and ask for help.


The first sketch you posted, which you said…

Is a sketch which could only work with a Blynk legacy local server running on
You don’t have a legacy local server, so that original sketch could never “work well”.

It took quite a few painful post to get to the position where I realised that this want actually the sketch you were using, and when you posted your actual sketch it was significantly different in structure and functionality.
Having wasted time analysing why your first sketch wasn’t working I didn’t feel like delving in to your second sketch, especially as a quick glance flagged-up some rather weird stuff that would take quite some time and follow-up questions to understand.