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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
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