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1  Using Arduino / LEDs and Multiplexing / Re: Changing the digital ports voltage? on: December 04, 2012, 10:59:28 am
Could you invite dhenry to stand next to you?

*ignored*
2  Using Arduino / LEDs and Multiplexing / Re: Changing the digital ports voltage? on: December 04, 2012, 10:22:41 am
Ok, I stand corrected...
3  Using Arduino / LEDs and Multiplexing / Re: Changing the digital ports voltage? on: December 04, 2012, 05:36:49 am
Quote
 So. 5/.025 = 250.

(dhenry) Ohm's law applies to just linear devices. The above calculation reflects your complete lack of understanding about Ohm's law.

It still can be used here, just not the way you did - the resulting current would be considerably less what what you your calculation suggested.

In this case...  Even if you take into account forward voltage drop of a typical 5 mm LED, you still end up with 220 ohms (Or 180 ohms if you went the other way in standard  values).  If you do *not* understand how Ohms law applies to control the amount of current in a simple 5V LED circuit, those who take your advise should do so with *much* suspicion now.

Ohms Law calculation is about the resistor... which is linear... and used to control the current in that section of the circuit... which includes and LED, which for all practical purposes is a unidirectional conductor.  

It is YOU who do not understand. That is clear to me now.

Guys - please stop the flaming... I thought this forum was about helping people interested in using Arduinos in their different projects, not for flaming those who try to help!

@pwillard - I think You too have a reason to review the link posted by Grumpy_Mike. Btw, Your calculation is wrong unless You have different laws of mathematics than the rest of us... 5/0.025 is not equal to 250 - it is equal to 200... And to be honest, if You use a 220 ohm resistor You will end up with a dimly lit led...

@Code - Do not drive the leds directly from an Arduino pin without any current limitation, You may/will end up letting the magic smoke out. Check the specs for Your leds (voltage drop and current needed) and read the link posted by Grumpy_Mike. It is imho a good guide to the correct way to light a standard low power led. Good luck with Your project!

4  Using Arduino / Microcontrollers / Re: Boot loading 168A-PU on: October 30, 2012, 06:34:21 am
Well, if you supply the correct device signature it should work...
5  Using Arduino / Programming Questions / Re: my micro cotroller does nothing after uploading a program on: September 27, 2011, 07:43:12 am
It could be a good idea to include your code in your posting...
6  Using Arduino / LEDs and Multiplexing / Re: Control RGB LED Strip with sharp distance sensor on: July 28, 2011, 06:12:09 am
You need to set the blue and red pins to zero.
7  Using Arduino / Microcontrollers / Re: ISP Bootloader onto ATMEGA328-AU + AVR Pocket Programmer on: July 14, 2011, 05:59:18 am
The signature bytes identifies the device You are trying to program - they shouldn't be confused with the fuse bytes. BTW I got the values from the data sheet You linked to (the row above the one You refered to). I guess You need a new entry in Your config file for AVRDude where You input the correct signature bytes.
8  Using Arduino / Microcontrollers / Re: ISP Bootloader onto ATMEGA328-AU + AVR Pocket Programmer on: July 14, 2011, 04:23:35 am
Try using the signature bytes for the ATmega328 (i.e., 0x1E 0x95 0x14) instead of the signature bytes for ATmega328P.
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