[ECOS] Time problem: Clock running slow

[Iris Lindner]

Hi everyone,
we just encountered a problem with our clock: It is running slow with 
approximately 24 seconds per hour.

Some information: We use a PowerPC MPC8347 and its RTC (hardware wallclock). 
As far as I could see there is an optimization for reducing i2c actions: Once 
at startup the RTC is read in get_current_time() (with get_hw_seconds()). 
Afterwards get_current_time() always returns the result of this first read 
out plus cyg_current_time()-result.
This leads to a correct time at booting, but from then on the mentioned delay 
of 24 sec per hour.

The real-time clock constants are: numerator=1 000 000 000, denominator=1000, 
period=66500 (so 1 tick = 1 ms). (And I've verified the chip's I/O bus speed 
as well as the basic core speed.)

Could there be a problem with these constants? Or perhaps interrupts 
disturbing the clock interrupt?
Thanks in advance for any help / idea / comment!!
cu
Iris

-- 
Iris Lindner
Software Development

Industrial Print and Apply Labelling

www.Logopak.com

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