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RE: timer
- To: mekala natarajan <mekala_natarajan at yahoo dot com>
- Subject: RE: [ECOS] timer
- From: Gary Thomas <gthomas at cambridge dot redhat dot com>
- Date: Thu, 17 May 2001 07:49:55 -0600 (MDT)
- Cc: ecos-discuss at sources dot redhat dot com
- Organization: Red Hat, Inc.
On 17-May-2001 mekala natarajan wrote:
> Hi,
> I tried running the intr.c(from tests)program HAL
> interrupt API test.
>
> I disabled the provide real time clock option.
>
> This is the output which i get
>
> PASS: Hal interrupt test
> EXIT: OK
>
> The isr routine is not getting called.
It has to be - that's the only way the test can pass.
>
> I am using MBX 860 as my target.
>
What does any of this have to do with your question below?
> Regards,
> mekala
>
>
>
>
>
> --- Gary Thomas <gthomas@cambridge.redhat.com> wrote:
>>
>> On 15-May-2001 mekala natarajan wrote:
>> > Can someone tell me the timer chip(and clock
>> > frequency) that is used in MBX kit.
>> >
>> > (eg.,For i386 pc target, the timer chip is 8254
>> whose
>> > clock frequency is 1193180HZ, from which we derive
>> at
>> > the kernel clock of 10ms.)
>> >
>> > Basically i want to run my application within a
>> time
>> > frame of 2ms(which is less than a tick).Within
>> this
>> > 2ms frame, i need to get the current time at
>> various
>> > points of the frame which will be in terms of
>> > microseconds.But ecos get current time system call
>> > will return time in terms of ticks. For this to
>> happen
>> > i reduced the tick resolution to 500us. But with
>> this
>> > configuration performance is degrading, since most
>> of
>> > time is getting wasted in processing the
>> interrupt.
>> >
>> > Now i don't want to use the kernel clock.
>> >
>> > How can i solve this problem.
>> >
>> > Can i directly access the timer chip and derive
>> the
>> > desired periodicity from this.
>> >
>> > Is this possible?
>> >
>> > If yes.How can i do this?
>> >
>>
>> The HAL_CLOCK_READ() will get you just what you
>> want. It will
>> return the time (in hardware clock ticks) since the
>> last system
>> clock timer interrupt. Thus it is a measure of time
>> within the
>> current "tick" (heartbeat). You can easily convert
>> the value
>> returned into us or ms.
>>
>> Look at 'kernel/current/tests/tm_basic.cxx' for
>> examples of how
>> to use it and how to convert the result into common
> units.
>
>
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