AVR-Chat

I don't have a Tiny13 data sheet in front of me, but I
would expect some timing restrictions, like there are for
disabling the watchdog. You MAY need to write to the Change
Enable bit, then within a specific time window, write the
new clock config. The data sheet ought to be pretty
explicit about the procedure.

Jim

On Mon, 20 Nov 2006 22:47:54 -0700
 "Cat C" <catalin_cluj@hotmail.com> wrote:
> I don't know much about your specific case, and you don't
> say quite enough, 
> but if:
> 
> 0x80;  // enable the Clock Prescaler Change Enable bit
> and
> 0x02;  // system clock divide by 4
> 
> Maybe you want:
> CLKPR=0x82
> 
> Cat
> 
> ----Original Message Follows----
> From: "Richard Cooke" <rcooke@digitalwavelength.com>
> Reply-To: AVR-Chat@yahoogroups.com
> To: AVR-Chat@yahoogroups.com
> Subject: [AVR-Chat] How do you change the clk speed?
> Date: Tue, 21 Nov 2006 05:23:08 -0000
> 
> Hi Folks,
> 
> I'm working on the ATtiny13 with the AVR Dragon and the
> latest version
> of AVR Studio (4.12 SP4).  I guess I don't understand how
> to change
> the clock frequency correctly.  I read the manual and I
> thought that
> if I used:
> 
> CLKPR=0x80;  // enable the Clock Prescaler Change Enable
> bit
> CLKPR=0x02;  // system clock divide by 4
> 
> Isn't this the proper way to change the clock?  I'm
> measuring the
> current and I see no change.  I'm running the chip at 5V
> and according
> the the spec sheet I should measure a little over 1ma at
> 1.2MHz.
> 
> Any ideas?
> 
> Thanks,
> 
> Richard Cooke
> 
> 
> 
> 
> 
> Yahoo! Groups Links
> 
> 
> 
>
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