esp_NANO

void setup()
{
  Serial.begin(115200);  //
}
void loop()
{
  recivestrfromserial();
}
//>>>>>>>>>>>>>>>>>>> my Programs

void Program_vPin5(String strvPin) {
}
//etc ...

void Program_vPin29(String strvPin) {
}

//from APP to NANO   >>>>>>>>>>>>>>>>
// equivalent BLYNK_WRITE(VPin)

void Blynkwrite(String str2) {
  byte pin2;
  String strdata2;
  if (str2.charAt(0) != 'V') pin2 = 199; else {
    String istr = str2.substring(1, str2.indexOf(':')); // nr vPin
    pin2 = istr.toInt();
    strdata2 = str2.substring(str2.indexOf(':') + 1); // if nr vPin typ int
  }
  switch (pin2 + 1) { // Jump to program recived vPin
    case 5: Program_vPin5(strdata2);  break;
    // etc....
    case 30: Program_vPin29(strdata2);  break;
   // case 200:   Serial.println("ERROR - no V");  break; //Program for error
    default: ;
  }
}

// equivalent   Blynk.virtualWrite(VPin, Data);

void BlynkvirtualWrite (byte vPin, String z) {
  String  str1 = 'v' + String(vPin) + ':' + z;
  sendstrtoserial(str1);
}

// ....................................... recive string from serial

bool  stringComplete = false;
String inputString = "";
byte licznikodbioru = 0;

void recivestrfromserial () {
  if (stringComplete) {
    Blynkwrite(inputString);
    inputString = "";
    stringComplete = false;
    licznikodbioru = 0;
  }
}

void serialEvent() { //odbiór string z Serial
  // Serial.println("odbior");
  while (Serial.available()) {
    licznikodbioru++;
    char inChar = (char)Serial.read();
    inputString += inChar;
    if (inChar == '\n') {
      stringComplete = true;
    }
    if (licznikodbioru > 50) inputString = "";
  }
}

// ................................. send string to serial
void sendstrtoserial (String toserial) {
  Serial.println(toserial);
}