Re: [Gumstix-users] Q: Change GPIO9 from 8kHz to 32kHz...

[<zoi...@ya...>]

--- On Tue, 10/21/08, Dave Hylands <dhy...@gm...> wrote:

> I took a quick look at the PXA270 datasheet, and I only see
> HZ_CLK on
> GPIO9 (as AF1). AF3 seems to be CHOUT.
> 
> CHOUT seems to be a periodic timer output, so presumably
> you could
> reprogram the timer to get anny frequency you want.
> See chapter 22 of the developer's manual.

Hi, Dave...

Thanks!

Yes, in fact the Developer's manual talks about setting registers to change the frequency (for CHOUT0 on GPIO9 which is AF3 out), but I can't seem to access those registers through pxaregs. (E.g. OMCR10 or OSMR10). My rough guess (please note I am a noob) is those registers haven't been mapped in pxaregs yet. (Or maybe, I'm just not reading the results of pxaregs correctly?)

Is there a way to set these regs from userspace so I can get the correct frequency? I'm using linux 2.6.21gum.

The reason I would like userspace is I'm hoping to avoid recompile/reflash of the kernel. I had some issues getting modules to compile with my current stable configuration, and I'm afraid of opening up a new can of worms with kernel/module compile problems, reflashing problems, etc.