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RE: Re: How to set clock related options?


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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