RGB LED

pootintootin

So, a friends and I are trying to program a single RGB LED to work with ColorPAL for a competition coming up on the 29th. We can get the ColorPAL to work flawlessly but we can't so much as turn on the LED. It doesn't short circuit because the light still comes on and the LED we are using is https://www.parallax.com/product/28085. Any help would be much appreciated.

DaveJenson

Check that same page for the documentation and examples...

tomcrawford

Sorry, that part cannot be driven with BS-2. Takes a prop.

You could drive a "bare" RGB led with three DACs using a BS2.

kwinn

tomcrawford wrote: »

Sorry, that part cannot be driven with BS-2. Takes a prop.

You could drive a "bare" RGB led with three DACs using a BS2.

Check the note at the bottom of the page for an explanation of why the BS2 will not work with the WS2812. A Propeller Mini would be a good choice for this project.

Buck Rogers

tomcrawford wrote: »

Sorry, that part cannot be driven with BS-2. Takes a prop.

You could drive a "bare" RGB led with three DACs using a BS2.

That amazing part, yes to the Prop.

However it is indeed possible to drive one via the BS2. Ask Google carefully about it.

tomcrawford

Well, I googled very carefully and think Buck Rogers may be suggesting WS2801. I didn't find any integrated with LEDs but it is worth looking for.

Buck Rogers

tomcrawford wrote: »

Well, I googled very carefully and think Buck Rogers may be suggesting WS2801. I didn't find any integrated with LEDs but it is worth looking for.

Close but no smelly burning object that makes some of us look for burning brush.... In fact I meant an ordinary RGB LED and a BS2. A fellow named Fox had a site up where he claimed he did BS2 related consulting and had it there. And I found it then using Google. Gone now the site is.

tomcrawford

I got to thinking a little more about this; why wouldn't PWM (Pulse Width Modulation) work just fine. Use an Op Amp in follower configuration for each channel (R,G,B) to keep the cap from discharging too quickly.

The attitude attached diagram shows what I did. The voltage at the output of the op amp is linear wrt input values from 100 to 180 or so, giving a range of 80 steps which is way more than the eye can see (at least my eye).