[ECOS] at91Arm7sek running without the pll

[ECOS] at91Arm7sek running without the pll

[Tobias Nielsen]

I have been sitting for some time to try to figure out a way to
completely skip the PLL AND at the same time use the main oscillator
bypass feature. I can see that the usage of the PLL is more or less
directly coded in to a macro in the header:

hal/arm/at91/at91sam7s/current/include/hal_platform_setup.h

But if i want to completely bypass that feature and follow the
instructions in the datasheet that states OSCBYPASS should be set to 1
and MOSCEN must be set 0 - i have absolutely no idea on how to put
that functionality in to the system without hacking a lot of code that
i in principle have no knowledge about...

Do anyone know how to make that bypass?
-- 
Yours kindly

Tobias Nielsen

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Re: [ECOS] at91Arm7sek running without the pll

[Andrew Lunn]

On Mon, Feb 25, 2008 at 03:47:26PM +0100, Tobias Nielsen wrote:
> I have been sitting for some time to try to figure out a way to
> completely skip the PLL AND at the same time use the main oscillator
> bypass feature. I can see that the usage of the PLL is more or less
> directly coded in to a macro in the header:
> 
> hal/arm/at91/at91sam7s/current/include/hal_platform_setup.h
> 
> But if i want to completely bypass that feature and follow the
> instructions in the datasheet that states OSCBYPASS should be set to 1
> and MOSCEN must be set 0 - i have absolutely no idea on how to put
> that functionality in to the system without hacking a lot of code that
> i in principle have no knowledge about...
> 
> Do anyone know how to make that bypass?

It will be a little bit messy.

Why do you need to turn the PLL off? Can you live with the PLL simply
multiplying by 1 and dividing by 1?

            Andrew

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Re: [ECOS] at91Arm7sek running without the pll

[Tobias Nielsen]

Nope, i have a situation where the the external components to drive
the PLL is not connected - therefore i have to run without the PLL

2008/2/25, Andrew Lunn <andrew@lunn.ch>:
> On Mon, Feb 25, 2008 at 03:47:26PM +0100, Tobias Nielsen wrote:
>  > I have been sitting for some time to try to figure out a way to
>  > completely skip the PLL AND at the same time use the main oscillator
>  > bypass feature. I can see that the usage of the PLL is more or less
>  > directly coded in to a macro in the header:
>  >
>  > hal/arm/at91/at91sam7s/current/include/hal_platform_setup.h
>  >
>  > But if i want to completely bypass that feature and follow the
>  > instructions in the datasheet that states OSCBYPASS should be set to 1
>  > and MOSCEN must be set 0 - i have absolutely no idea on how to put
>  > that functionality in to the system without hacking a lot of code that
>  > i in principle have no knowledge about...
>  >
>  > Do anyone know how to make that bypass?
>
>
> It will be a little bit messy.
>
>  Why do you need to turn the PLL off? Can you live with the PLL simply
>  multiplying by 1 and dividing by 1?
>
>
>             Andrew
>


-- 
Yours kindly

Tobias Nielsen

-- 
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Re: [ECOS] at91Arm7sek running without the pll

[Andrew Lunn]

On Mon, Feb 25, 2008 at 05:05:38PM +0100, Tobias Nielsen wrote:
> Nope, i have a situation where the the external components to drive
> the PLL is not connected - therefore i have to run without the PLL
> 
> 2008/2/25, Andrew Lunn <andrew@lunn.ch>:
> > On Mon, Feb 25, 2008 at 03:47:26PM +0100, Tobias Nielsen wrote:
> >  > I have been sitting for some time to try to figure out a way to
> >  > completely skip the PLL AND at the same time use the main oscillator
> >  > bypass feature. I can see that the usage of the PLL is more or less
> >  > directly coded in to a macro in the header:
> >  >
> >  > hal/arm/at91/at91sam7s/current/include/hal_platform_setup.h
> >  >
> >  > But if i want to completely bypass that feature and follow the
> >  > instructions in the datasheet that states OSCBYPASS should be set to 1
> >  > and MOSCEN must be set 0 - i have absolutely no idea on how to put
> >  > that functionality in to the system without hacking a lot of code that
> >  > i in principle have no knowledge about...
> >  >
> >  > Do anyone know how to make that bypass?
> >
> >
> > It will be a little bit messy.
> >
> >  Why do you need to turn the PLL off? Can you live with the PLL simply
> >  multiplying by 1 and dividing by 1?

Then i suggest you add CDL control of this. A new option say

CYGBLD_HAL_ARM_AT91_PLL_BYPASS

So that CYGNUM_HAL_ARM_AT91_CLOCK_SPEED is calculated correctly, you
want some requires statements in the CYGBLD_HAL_ARM_AT91_PLL_BYPASS
option. Something like

cdl_option CYGBLD_HAL_ARM_AT91_PLL_BYPASS {
    display  "Bypass the PLL"
    flavor bool
    default_value 0

    requires CYGNUM_HAL_ARM_AT91_PLL_MULTIPLIER == 2
    requires CYGNUM_HAL_ARM_AT91_PLL_DIVIDER == 1

    description "
       The PLL requires external components which not all targets have.
        Enabling this option bypasses the PLL."
}

Then in hal_platform_setup.h add the necassary code inside #ifdefs.

     Andrew

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Re: [ECOS] at91Arm7sek running without the pll

[Tobias Nielsen]

Oki, i will try to work with it a bit then... - thx

2008/2/25, Andrew Lunn <andrew@lunn.ch>:
> On Mon, Feb 25, 2008 at 05:05:38PM +0100, Tobias Nielsen wrote:
>  > Nope, i have a situation where the the external components to drive
>  > the PLL is not connected - therefore i have to run without the PLL
>  >
>  > 2008/2/25, Andrew Lunn <andrew@lunn.ch>:
>  > > On Mon, Feb 25, 2008 at 03:47:26PM +0100, Tobias Nielsen wrote:
>  > >  > I have been sitting for some time to try to figure out a way to
>  > >  > completely skip the PLL AND at the same time use the main oscillator
>  > >  > bypass feature. I can see that the usage of the PLL is more or less
>  > >  > directly coded in to a macro in the header:
>  > >  >
>  > >  > hal/arm/at91/at91sam7s/current/include/hal_platform_setup.h
>  > >  >
>  > >  > But if i want to completely bypass that feature and follow the
>  > >  > instructions in the datasheet that states OSCBYPASS should be set to 1
>  > >  > and MOSCEN must be set 0 - i have absolutely no idea on how to put
>  > >  > that functionality in to the system without hacking a lot of code that
>  > >  > i in principle have no knowledge about...
>  > >  >
>  > >  > Do anyone know how to make that bypass?
>  > >
>  > >
>  > > It will be a little bit messy.
>  > >
>  > >  Why do you need to turn the PLL off? Can you live with the PLL simply
>  > >  multiplying by 1 and dividing by 1?
>
>
> Then i suggest you add CDL control of this. A new option say
>
>  CYGBLD_HAL_ARM_AT91_PLL_BYPASS
>
>  So that CYGNUM_HAL_ARM_AT91_CLOCK_SPEED is calculated correctly, you
>  want some requires statements in the CYGBLD_HAL_ARM_AT91_PLL_BYPASS
>  option. Something like
>
>  cdl_option CYGBLD_HAL_ARM_AT91_PLL_BYPASS {
>     display  "Bypass the PLL"
>     flavor bool
>     default_value 0
>
>     requires CYGNUM_HAL_ARM_AT91_PLL_MULTIPLIER == 2
>     requires CYGNUM_HAL_ARM_AT91_PLL_DIVIDER == 1
>
>     description "
>        The PLL requires external components which not all targets have.
>         Enabling this option bypasses the PLL."
>  }
>
>  Then in hal_platform_setup.h add the necassary code inside #ifdefs.
>
>
>      Andrew
>


-- 
Yours kindly

Tobias Nielsen

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