Blynk.syncVirtual doesn't work as expected

Need Help With My Project
1

I want to read V1, V2 state from Blynk server when Arduino is on

So I expected the following code work like…

if Blynk connected => printed “BLYNK_CONNECTED()” => Call BLYNK_WRITE(V1) and BLYNK_WRITE(V2) with some print lines => First = false

However, these codes actually call BLYNK_WRITE after first = false.

Thus the serial monitor shows:

[12154] Ready (ping: 209ms).
BLYNK_CONNECTED()
Frist = true
Call V1
Call V2
Frist = false
BLYNK_WRITE(V1)
BLYNK_WRITE(V2)

What’s wrong with my code?

#define BLYNK_PRINT Serial

#include <SPI.h>
#include <Ethernet.h>
#include <BlynkSimpleEthernet.h>

BlynkTimer timer;
//Blynk setting-----------------------------------------------------------------
byte arduino_mac[] = {};
IPAddress arduino_ip ();
IPAddress dns_ip     ();
IPAddress gateway_ip ();
IPAddress subnet_mask();
char auth[] = "";
//Blynk setting-----------------------------------------------------------------

int First = true;
int A;
int B;

void setup()
{
  Serial.begin(9600);
  Blynk.begin(auth, "blynk-cloud.com", 80, arduino_ip, dns_ip, gateway_ip, subnet_mask, arduino_mac);
}

BLYNK_CONNECTED()
{
  Serial.println("BLYNK_CONNECTED()");
  Serial.println("Frist = true");
  Serial.println("Call V1");
  Blynk.syncVirtual(V1); //Call V1
  Serial.println("Call V2");
  Blynk.syncVirtual(V2); //Call V2
  First = false;
  Serial.println("Frist = false");
}


BLYNK_WRITE(V1)
{
  Serial.println("BLYNK_WRITE(V1)");
  A = param.asInt();
  if (First)
  {
    Serial.println("FirstA");
  }
  else
  {
    //Some Code
  }
}

//Wind
BLYNK_WRITE(V2)
{
  Serial.println("BLYNK_WRITE(V2)");
  B = param.asInt();
  if (First)
  {
    Serial.println("FirsB");
  }
  else
  {
    //Some Code
  }
}


void loop()
{
  Blynk.run();
}
2

I don’t think there is anything wrong with your code.

I am pretty sure that ** Blynk.syncVirtual(xx);** will only get called at the next Blynk.run() call which won’t happen until the BLYNK_CONNECTED() function has finished.

4

That’s mean Blynk.syncVirtual(xx); will work when next Blynk.run()? not the location of that code?

If I got it right, I’d have to approach it the other way.

1 Like
5

Yes - I’m pretty sure that how it works.

Maybe a dev can confim/deny this when they see this post?

6

If @JustBertC is correct, then simply add a Blynk.run(); immediately after your Blynk.syncVirtual(xx) commands and it should produce the result you expected.

Pete.

7

I liked this method and tried it but it works like the code above.

BLYNK_CONNECTED()
{
  Serial.println("BLYNK_CONNECTED()");
  Serial.println("Frist = true");
  Serial.println("Call V1");
  Blynk.syncVirtual(V1); //Call V1
  Blynk.run();
  Serial.println("Call V2");
  Blynk.syncVirtual(V2); //Call V2
  Blynk.run();
  First = false;
  Serial.println("Frist = false");
}
8

I liked this method and tried it but it works like the code above.

BLYNK_CONNECTED()
{
  Serial.println("BLYNK_CONNECTED()");
  Serial.println("Frist = true");
  Serial.println("Call V1");
  Blynk.syncVirtual(V1); //Call V1
  Blynk.run();
  Serial.println("Call V2");
  Blynk.syncVirtual(V2); //Call V2
  Blynk.run();
  First = false;
  Serial.println("Frist = false");
}
9

What about this?..

BLYNK_CONNECTED()
{
  Blynk.syncVirtual(V1); //Call V1
  Blynk.syncVirtual(V2); //Call V2
  Serial.println("BLYNK_CONNECTED()");
  Serial.println("Frist = true");
  Serial.println("Call V1");
  Serial.println("Call V2");
  First = false;
  Serial.println("Frist = false");
}
10

This code works just like the first one. Perhaps Blynk.syncVirtual signals Blynk.run to call BLYNK_WRITE instead of calling BLYNK_WRITE.