[ECOS] RE: Re: How to set clock related options?

[Savin Zlobec]

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



-- 
Before posting, please read the FAQ: http://sources.redhat.com/fom/ecos
and search the list archive: http://sources.redhat.com/ml/ecos-discuss