RGB LED driver, Any comments?

[paxmowa]

Dude! You're so right.

Lack of sleep makes pax go crazy.

Thanks a bunch, i'll rework it after some sleep... or coffee...

Steve

[keithdoxey]

Dude! You're so right.
Steve

Apart from when I am wrong!!!

PORT D
PNP collector to +5V feeding emitter to common Anode
Take the base to 0V via resistor to turn on an LED

Should read

PORT D
PNP *EMITTER* to +5V feeding *COLLECTOR* to common Anode
Take the base to 0V via resistor to turn on an LED


That'll teach me to reply in a hurry before dashing out to collect the kids from school
DOH !!!!

[paxmowa]

Thanks for the efford Keith.

After a bit of sleep and with a cleared head I made up this:

Updated:


Swapped PNP and NPN transistors around, replaced BC547 by BD139.

It aint finished yet i guess.

I checked the specs for the RGB leds and green and blue chips are rated 3.5 to 3.8 volts, red chip is GaAlAs rated at 1.85 to 2.2 volts. The 3.3 volts from the voltage regulator is to high for the red chip and to low for the blue and green. Will prolly go to 5V supply and put resistors in series with each chip.

Anyways, thanks again for the help so far,
Steve

UPDATE:
This is the third version, added resistors in series with each led chip, this should be almost complete i think. Now only add the PIC16F777 and power supply.

[paxmowa]

hmmm, I figure there's also the voltage drop over the transistors. about 0.6 volt each.

So the resistors for blue and green should be 10 ohm and for the red should be something like 82 ohm.

Getting there... slowly, but getting there none the less.

Steven

[charudatt]

Hello PAX / Other,

I am trying a very similar project in which I send a byte (actually 3 bytes for R-G-B) information for each of the color LED via the RS232 Port to form a Colour Combination.

I am plannig to go about using 3 12F629 for each of the LED's. I am having some problem of communicating the PIC's with the RS232.

Can anyone share some code samples for the RGB LED out here ?

regards

[peu]

Im using a single 12F683 (or 12F675) for controlling the RGB channels and I still have space for an extra potentiometer (for sweep speed) and 2 buttons.



For PWMing I use PWM instead HPWM, of course if you have 3 HPWM is a little easier, but not much...

you share a common ground and use a 7805 regulator for the pic, then you can power the regulator and the leds with any value from 5-24V (+ after the resistors)

I drive luxeon leds without problem

Have fun

[ERIK]

Hey Peu, I'm working on pretty much the same thing with a 12F675 PWMing to 3 Mosfets. Everything is working well except I'm finding when I PWM from GP2 and GP4 the MOSFETs don't really pulse they pretty much just stay on, or switch off when the cycle gets low enough. I'm not sure why, I've poked the ANSEL and CMCON, but it seems maybe the output voltage on those pins is a little different or something. Anyone have any ideas what might be going on? I see you are driving your green channel with GP2, does that work fine for you?

[eduman]

I am a new user.Where is the asm or hex code for this cicuit.
Thank you very much.