Pages: [1]   Go Down
Author Topic: Pin issue  (Read 288 times)
0 Members and 1 Guest are viewing this topic.
Offline Offline
Newbie
*
Karma: 0
Posts: 9
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hi everyone!

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

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

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

Lucky number 13 ????

Logged

Offline Offline
Edison Member
*
Karma: 116
Posts: 2205
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

weak pull-up.
Logged

Global Moderator
Melbourne, Australia
Online Online
Brattain Member
*****
Karma: 511
Posts: 19365
Lua rocks!
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

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.
Logged

http://www.gammon.com.au/electronics

Please post technical questions on the forum - not to me by personal message. Thanks a lot.

Left Coast, CA (USA)
Offline Offline
Brattain Member
*****
Karma: 362
Posts: 17307
Measurement changes behavior
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

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.

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

Lefty
« Last Edit: November 18, 2012, 11:36:55 am by retrolefty » Logged

Pages: [1]   Go Up
Jump to: