Re: [oopic] Common Anode RGB Leds

Let me add to what Richard was saying.

You can use any of the IO lines and the oPWML objects. They have about
a 500Hz PWM clock and 16 levels, which should be fine for your work as a
rule. When you use PWM on the common anode units remember to reverse
what you expect - IOW, a PWM of 14 would be dim or off and a PWM value
of 1 would be bright. I'd start with 1K limiting resistors and drop
down until you get to what you want, making sure that you don't exceed
20mA on the IOline. You should measure the voltage across the LED to
see what it drops to know what resistor values you need for the max
current allowed.

DLC

jim_three_uk wrote:
> Hi,
>
> I've recently been given a bunch of flux-type RGB LEDs which I planed
> to use in a small lighting project controlled with my OOPIC-R via PWM.
> The problem is that the LED's are common anode, and I was expecting
> common cathode. Is there any way to make use of these LEDs without
> having to build any circuitry external to the oopic-r? I'm only
> planning on running four of these RGB leds, (4x3 colours, 12 LEDs in
> total) not a very big array. The oopic-r would (as you can probably
> guess) simply fade between R, G and B over time. I'm pretty much a
> beginning with the electronics side of engineering, but from reading
> round I've found that to control common anode LED arrays (seven segment
> displays or RGB LEds) you have to sink the current coming from the
> cathodes. Is the OOPIC-R able to do this through its signal pins?
>
> cheers
>
> Jim
>
>
>
>
>
> Yahoo! Groups Links
>
>
>

--
------------------------------------------------------
Dennis Clark ooPIC Tech Support
www.oopic.com
------------------------------------------------------

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