Can this setup hurt the digital pin ?

Forum 2005-2010 (read only) Hardware Interfacing
1

Hello everyone,

I need to know if this setup can damage arduino digital pin:

http://www.minasambiente.com.br/media/images/common/ardpin.jpg

This way the led will blink when the digital pin is set as LOW.

I know this is not the usual manner to blink a led. I have in here some numeric digital display that share the positive pole and you control the segments by hooking them to ground. So this is the type of setup I will need to use to use the display.

The display data sheet: http://kr.ic-on-line.cn/IOL/datasheet/a-503ga_815894.pdf A-503G-A is the model I'm using.

It's possible to use some ordinary shift register to control the display?

Appreciate any clue/suggestion.

Cheers,

Rodrigo

2

I know this is not the usual manner to blink a led.

It isn't?

Have a look at the AVR's current source and sink capabilities.

3

Hello AWOL,

Maybe it is and Im just not awared.
The way I knew to blink a led is by making it blink when digital pin is set as HIGH.

And thinking a little more about the scheme, the led is an diode so no drain when pin is set to HIGH.. I suppose. Didnt think about it lately. Im just returning to my amateur electronics after 1+ year... must put brain to work again.

Very thanks for the reference !

Rodrigo

4

It's exactly how you power common anode LEDs.
The AVR pins can source or sink a maximum (absolute - don't go near) of 40mA, up to a per-chip limit of about 200mA.
Your 1kohm resistor will keep the current (and the brightness) down.