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Re: Dependence of software on system frequency
- From: Andrew Lunn <andrew at lunn dot ch>
- To: Miguel J Vega <mserrano at engin dot umich dot edu>
- Cc: ecos-discuss at sources dot redhat dot com
- Date: Tue, 26 Oct 2004 09:40:31 +0200
- Subject: Re: [ECOS] Dependence of software on system frequency
- References: <Pine.LNX.4.58.0410252147220.21311@red.engin.umich.edu>
On Mon, Oct 25, 2004 at 09:52:20PM -0400, Miguel J Vega wrote:
> Hi,
>
> I am attempting to under-clock an MPC555 board. I can manually
> reduce the clock frequency, but I know some ecos software
> depends on the clock, but unfortunately clock frequency is not an option
> in the ecos configuration. In order to properly under-clock the board I
> must know what software would depend on the system frequency. So far I
> have identified some serial module register values that depend on the
> sytem frequency. Does anyone know what else I should check for?
You do have some controls. Take a look at CYGNUM_HAL_RTC_DENOMINATOR,
CYGNUM_HAL_RTC_NUMERATOR, CYGNUM_HAL_RTC_PERIOD &
CYGHWR_HAL_POWERPC_BOARD_SPEED
If you have the eCos clock still ticking at its normal rate you should
not have problems with the rest of the system. If however the main
eCos clock is running at a different rate you should take a look at
the network stack.
Andrew
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