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RE: Re: How to set clock related options?
- From: Savin Zlobec <savin at elatec dot si>
- To: caocangmou at sina dot com
- Cc: ecos-discuss at sources dot redhat dot com
- Date: Thu, 25 Sep 2003 15:55:35 +0200
- Subject: [ECOS] RE: Re: How to set clock related options?
- References: <3F72E930.2000101@elatec.si>
Savin Zlobec wrote:
caocangmou wrote:
But, I got a configuration from template(Akizuki H8/3068) :
Real-time clock numerator : 1000000000
Real-time clock denominator : 100
Real-time clock base prescale : 8192 Real-time
clock period :10
OSC/Clock Frequency :20000000
It seems not the case .What does period really mean?
CYGNUM_KERNEL_COUNTERS_RTC_PERIOD which defaults to
CYGNUM_HAL_RTC_PERIOD is
used to initialize you system clock hardware. Ecos tick is usually
implemented with a hw timer which gives
periodic interrupts. The CYGNUM_HAL_RTC_PERIOD is calculated so that
you get an interrupt every
10ms (the default) and it depends on your timer hardware. Changing the
tick requires setting the
CYGNUM_HAL_RTC_NUMERATOR, CYGNUM_HAL_RTC_DENOMINATOR and
CYGNUM_HAL_RTC_PERIOD (if it is not automatically calculated from the
previous two - look how it is
calculated in cdl - it can only depend on your frequency - in that
case it is probably set to 10ms).
I just realized that what I said about the hw timer it is not entirely
correct. The timer should only be able to generate
an interrupt after a desired amount of time. The kernel takes care of
the periodic aspect by resetting the timer with
HAL_CLOCK_RESET in ISR.
savin
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