How do I set PWM speed?

Forum 2005-2010 (read only) Hardware Troubleshooting
1

I hear default is around 30kHz, I need mine to be 1/16th of the clock speed, which is 16MHz.

Also, can I change this with just the USB arduino board and an ATMEGA168? I don't want to buy a dedicated burn programmer.

Thanks, I tried searching for a while but found nothing on PWM speed...

(The reason I ask is that I need to clock a chip synchronously with the arduino clock at 1MHZ and CD4024 can't work that fast.)

2

You can set the PWM frequency as fast as half the clock speed, but it requires some fiddling with low-level registers. You can do it all in the setup() routine, but figuring out the exact commands isn't easy. You'll need to read the ATmega168 datasheet sections on timers. Sorry I can't offer more specific advice, but feel free to ask more questions and I'll see what I can do.

3

No, thanks man, I eventually think I had something, but I forgot to actually write an analogOut() when testing, and Apparently, I disabled an interrupt, so now I can't load new code in unless I reburn the bootloader on through ISP.

APPARENTLY, that is. I don't know very much at all about uCs and how they work, but I have a wiring board that I might try it on.

I deleted the actual code, but it would have worked mostly fine (didn't have the right prescale, but I can multiply freq with PLL). Anyway, if you know of a simple fix, I'd love to hear it but as it looks now, I'm going to be buying a parallel to ISP cable.

Thanks for the help!

4

I jsut lost my post, but I do have a question:

Where can I go to larn about those commands that set specific bits in the registers. I'd be comfortable doing it in ASM if I knew how. Do you know of any places I could go to learn about that?

5

You want the ATmega8 or ATmega168 processor manual. They cover all of it in detail. You can find them on Atmel's site.. .products, microcontrollers, avr, mega...