Pin issue

Projects Programming
1

Hi everyone!

Every pin on my arduino works fine but when i set this

pinMode(13, INPUT);
digitalWrite(13, HIGH);

the tiny LED on the board near TX/RX LEDs is dimmed on..

Lucky number 13 ????

2

weak pull-up.

3

As dhenry is trying to explain, doing that turns on the internal pull-up, which effectively connects the on-board LED to 5V via about a 50K resistor.

4

That shows how efficient modern day leds can be where even 100 micro-amps can generate some light!

Lefty