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*From*: AbdullahKhateeb Khan <khateeb4u at yahoo dot com>*To*: ecos-discuss at ecos dot sourceware dot org*Date*: Thu, 8 Dec 2005 23:33:33 -0800 (PST)*Subject*: [ECOS] Over-riding Real Time Clock

-- MY target system is an Intel Pentium-4 processor with a 2.4 GHz clock. My Host platform is an i386 based system. The default settings of RTC clock constants for i386 based system are Real-time clock numerator = 1000000000 Real-time clock denominator = 100 Real-time clock Period = 11932 In other words the clock frequency equals to 100Hz. This settng gives me a clock output such that the clocks drifts 20msec after 200sec. I have few questions regarding this - How can we minimize the RTC clock drift? - What will be the values of "Clock Hardware Initialization Value", "Clock Resolution numerator", "Clock Resolution Denominator" to configure the above mentioned Intel Pentium-4 processor for 2.4GHz clock I have used Over ride default clock setting option available in eCos Configuration tool to change the clock frequency. I got the following results for different Clock Hardware Initialization Value. Experiment #1: Clock Hardware Initialization Value=5966 Denominator = 1000,000,000 Numerator = 100 Resultant Clock frequency = 200Hz Experiment #2: Clock Hardware Initialization Value=11932 Denominator = 1000,000,000 Numerator = 100 Resultant Clock frequency = 100Hz Experiment #3: Clock Hardware Initialization Value=11932 Denominator = 1000,000,000 Numerator = 60 Resultant Clock frequency = 100Hz Experiment #4: Clock Hardware Initialization Value=23864 Denominator = 1000,000,000 Numerator = 100 Resultant Clock frequency = 50Hz I didnot observe any noticeable effect of Numerator and Denominator setting in changing the clock frequency. Why is it so? Only one parameter ("Clock Hardware Initialization Value") changes the clock frequency. If u see the above mentioned results then its clear that the Numerator value (100 or 60) does not change the resultant clock frequency i.e 100Hz. I have experienced the same problem while generating the 50Hz or 200Hz clock frequency i.e 'The value of Numerator and Denominator does not help in changing the clock frequency'. Thanx, Any help would be much appreciated. Regards, Abdullah __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss

**Follow-Ups**:**Re: Over-riding Real Time Clock***From:*Gary Thomas

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