And what is the value of rpm whe the problem is happening ?

itoa works, I use it every days

Some debug:

1) when i connect, the flag goes 1 and i control the RGB led;

2)On the app i put 2 char boxes [5], one for the temperature (i read the value no problem) and the other to show RPM of the engine. This second box shows always a flashing "00" and when it starts to generate numbers (rounds of engine) suddenly the connect_flag goes to 0( i need to reenter in the app).

I used your guide to convert from int to char with sprintf, itoa doesn't work.  I see right values in my serial monitor, but not in the app (no RPM, yes temperature).

This is my code, hope it helps:

if (currentmillis - lastmillis <= interval){ 
 detachInterrupt(IR);
 rpm = half_revolutions * ((60000/(currentmillis - lastmillis)));
 //Serial.print(rpm); 
 //Serial.print(" RPM");
 //Serial.print("\n");
 half_revolutions = 0;
 lastmillis = currentmillis;
 attachInterrupt(IR, rpm_fan, FALLING);
  }
sprintf (RemoteXY.giri, "%d", rpm);

ICACHE_RAM_ATTR void rpm_fan(){
  half_revolutions++;
 }

if (RemoteXY.connect_flag != 0) {
  // connection established
}
else {
  // connection off
}

if (??????????????????????)
  {
  RemoteXY.rgb_1_r=random(0,255);
  RemoteXY.rgb_1_g=random(0,255);
  RemoteXY.rgb_1_b=random(0,255);
  RemoteXY.slider=random(0,100);
  }

I tried:

• WiFi.status() != WL_CONNECTED

• !client.connected()

• WiFi.waitForConnectResult() != WL_CONNECTED

• WiFi.localIP().toString() == "0.0.0.0"

Which is the compatible function to use with the RemoteXY library??? I tried calling the WiFi.begin() function too.
Thanks