Built in and rx, tx leds

Other Hardware LEDs and Multiplexing
1

Hi! I uploaded to my mega 2560 the blink example and it made blink the BUILTIN led. But when I tried it slightly the same way it made blink the rx led and the delay function didn't work well.
I mean when I set the led HIGH and made a 1000 delay it didn't waited.
Why is that?

int num = 0;

void blink(int num) {
  int count = 1;
  for( ; ; ) {
    if(count == num) {
      Serial.println("END");
      digitalWrite(LED_BUILTIN, HIGH);
      delay(1000);
      digitalWrite(LED_BUILTIN, LOW);
      break;
    }
    else {
      Serial.println("ON GOING");
      digitalWrite(LED_BUILTIN, HIGH);
      delay(150);
      digitalWrite(LED_BUILTIN, LOW);
      count++;
    }
  }
}
void setup() {
  pinMode(LED_BUILTIN, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  blink(5);
}
2

If you look at a schematic for the Mega 2560, you'll see that while the LED_BUILTIN led is hooked up to the Mega, the Rx and Tx LEDs are not. They are connected to the 16u2.

3

The delay of 1000 works. Make it 10000 and count the 10 seconds.

4

@botond500
Are you sure the RX is blinking?
Wouldn't it be TX?
The TX will blink because you use the serial.

2 Likes
5

If you're talking about that code, try the following:

 for( ; ; ) {
    if(count == num) {
      Serial.println("END");
      digitalWrite(LED_BUILTIN, HIGH);
      delay(1000);
      digitalWrite(LED_BUILTIN, LOW);
      delay(1000);
      break;
    }
    else {
      Serial.println("ON GOING");
      digitalWrite(LED_BUILTIN, HIGH);
      delay(150);
      digitalWrite(LED_BUILTIN, LOW);
      delay(150);
      count++;
    }

​​

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6

I tried it first but it didn't work.

7

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