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My Name is...
04-25-2006, 04:39 AM
Is it possible to make a LED display w/ the BS2 using tri-color LEDs
If it is, then are there any schematics, along with programming help, and what would be necessary to build it.

Thanks.

PJ Allen
04-25-2006, 07:24 AM
Tri-Color... Red, Green, and Blue; Red, Green, 3-lead; Red-Green 2-lead??? What, what, what?

Zoot
04-26-2006, 12:40 AM
I just hooked up a bunch of bi-state red/green LEDs (red/green 2 lead) and it's very cool. This gives you off/red/green. See this thread http://forums.parallax.com/showthread.php?p=582634.

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When the going gets weird, the weird turn pro. -- HST

Paul Baker
04-26-2006, 01:13 AM
It all depends, if you just want 8 colors (black, red, green, blue, yellow, cyan, magenta, white) then its not too hard, you just need enough 595s to connect each of the elements to. If you want more colors, the task become "very difficult" (read impossible) without using additional specialized external components.

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1+1=10

Zoot
04-26-2006, 01:36 AM
You can also try the MAX6956, an I2C chip that drives 20-28 LEDs with current (intensity) and on/off registers for each LED. They're a bit pricier, but if you need like 6-8 shift registers, the price vs. space may balance out. With auto-incrementing register addresses, an I2C LED driver chip may make coding a lot of LEDs easier. DigiKey carries the MAX; both Jameco and Digikey carry lots of interesting LED driver chips for various purposes.

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When the going gets weird, the weird turn pro. -- HST

Paul Baker
04-26-2006, 02:32 AM
Im working on a board using the MAX7313, but it has had it's share of headaches. While the MAX7313 is 1/3rd the price of the MAX6956, it is voltage driven PWM, meaning current limiting resistors. The problem is the Vf of the RGB LEDs he wants to use are around 3.3V for the blue and green elements leaving no headroom for the resistors (the MAX7313 is a 3.3V device), and given the process variation of the LEDs is a variability of 1V Vf and he wants the entire array precisely color matched using enternal means (so loss of programmable color range doesn't happen), we have to use a dual supply of 5V for the LEDs, and driver transistors for each element.

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1+1=10

PJ Allen
04-26-2006, 02:44 AM
Paul Baker,

Are you and My Name Is... PM'ing all these details? Just wondering (I'm not busting you up) because there's only one post from him.

Paul Baker
04-26-2006, 03:27 AM
No no, its not My name is... that Im helping, its another member. Ive been helping him on the project for about 4-5 months now, eventually everything should be posted in the projects forum, its been progressing at a snails pace because I dont have much free time, even though my presence on the forums may speak otherwise.

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1+1=10

Post Edited (Paul Baker) : 4/25/2006 8:30:38 PM GMT