char red_led_state = LOW;
long red_led_previous_millis = 0;
int red_led_interval = 2000;

void setup() 
{
  Serial.begin(9600);
  delay(5000);
}

void loop() 
{
   long current_millis = millis();

   if (current_millis - red_led_previous_millis >= red_led_interval)
   {
    red_led_previous_millis = current_millis;

    int adcRes = analogRead(A5);
    
    char str[4];
    sprintf(str, "%d", adcRes);

    // use client.publish() to send the str here
    
   }
}