RGb LED Controller - Electronic Circuits Projects Diagrams Free

wcavanagh · 9th January 2004, 12:12 PM

I wonder if someone can help a poor man. I want to colour cycle a RGB LED smoothly through thounds of colours, it will be used to light up a lod etched in glass, so random colours would be great. I have been told PWM is what i need, I have a PICKit1 and a PicstarPlus programmer from Microchip. I am very new to this and just dont know where to start, I have some PIC12F675 Chips. Anyone recomend anything? PLEASE.......

Rescyou · 9th January 2004, 02:41 PM

What language are you programming in and what speed are you going to run the 675 at?

Resc.

wcavanagh · 9th January 2004, 02:51 PM

Going to use ASM as that seems to be all i can do with MPLAB, going to use the internal 4Meg clock

Rescyou · 9th January 2004, 03:20 PM

4mhz will work for 3-channels ok if you use the correct methods for pwm, as for ASM I can't help you on that.

Resc.

**Nigel Goodwin** · 9th January 2004, 03:37 PM

Quote:

Originally Posted by Rescyou

4mhz will work for 3-channels ok if you use the correct methods for pwm, as for ASM I can't help you on that.

Resc.

If he's got the PICKit1 (as he said), it comes with a Lite version of a C compiler - if that helps?.

TheAnimus · 9th January 2004, 09:57 PM

the best way would be to use a TMR0 interupt, then devide it down depending on what value you should have in a file register for each LED.

The TMR0 registrer at 4mhz u might want to use as a global biasing, at the end of the ISR add a value to the TMR0 register.

Thats a pritty rough outline, but it should work fine, you might find a lot of tweaking is needed to get nice linear values (odds are PWM won't provide a smooth change of light intensity with standard linear values)

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9th January 2004, 12:12 PM	(permalink)
wcavanagh	RGb LED Controller I wonder if someone can help a poor man. I want to colour cycle a RGB LED smoothly through thounds of colours, it will be used to light up a lod etched in glass, so random colours would be great. I have been told PWM is what i need, I have a PICKit1 and a PicstarPlus programmer from Microchip. I am very new to this and just dont know where to start, I have some PIC12F675 Chips. Anyone recomend anything? PLEASE....... __________________ ------- Regards, William Cavanagh

9th January 2004, 02:41 PM	(permalink)
Rescyou	Questions What language are you programming in and what speed are you going to run the 675 at? Resc.

9th January 2004, 02:51 PM	(permalink)
wcavanagh	Going to use ASM as that seems to be all i can do with MPLAB, going to use the internal 4Meg clock __________________ ------- Regards, William Cavanagh

9th January 2004, 03:20 PM	(permalink)
Rescyou	Info 4mhz will work for 3-channels ok if you use the correct methods for pwm, as for ASM I can't help you on that. Resc.

9th January 2004, 09:57 PM	(permalink)
TheAnimus	the best way would be to use a TMR0 interupt, then devide it down depending on what value you should have in a file register for each LED. The TMR0 registrer at 4mhz u might want to use as a global biasing, at the end of the ISR add a value to the TMR0 register. Thats a pritty rough outline, but it should work fine, you might find a lot of tweaking is needed to get nice linear values (odds are PWM won't provide a smooth change of light intensity with standard linear values)