Arduino UNO clone TX LED

Using Arduino Programming Questions
1

Hi there,

I'm using a Uno clone board.
This board had been working for me quite some time now.
Today I've loaded a test sketch below; and noticed that the Serial TX LED is blinking when I'm I rotate the Encoder.
Furthermore I noticed the "L" led is fully lit (always), after uploading a blank sketch.
Then I uploaded a the test blink sketch and the "L" LED is blinking.
Next while the test sketch is running, I grounded (with a jumper wire) the Arduino pin 2 (INT0), and saw the TX led lit for few seconds and goes off.

For my understanding so far these are all strange behaviors.
Anyone have an idea why this is happening?

/* Encoder Library - Basic Example
 * http://www.pjrc.com/teensy/td_libs_Encoder.html
 *
 * This example code is in the public domain.
 */

#include <Encoder.h>

// Change these two numbers to the pins connected to your encoder.
//   Best Performance: both pins have interrupt capability
//   Good Performance: only the first pin has interrupt capability
//   Low Performance:  neither pin has interrupt capability
Encoder myEnc(2, 3);
//   avoid using pins with LEDs attached

void setup() {
}

long oldPosition  = -999;

void loop() {
  long newPosition = myEnc.read();
  if (newPosition != oldPosition) {
    oldPosition = newPosition;
  }
}

Encoder CLK -> INT0
Encoder DT -> INT1

image
image779×673 112 KB

2

Obviously you don't have an UNO clone but a board that claims to be UNO compatible. An original Arduino UNO won't blink any LEDs given above code and wiring.

Post a link to the schematics of your so called "UNO" board as we cannot use the schematics of a real UNO (because that one doesn't show the strange behavior).

1 Like
3

Thanks for your kind reply.
After burning the UNO boot loader, things went back to normal.
Very strange.

4

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