I am reading the spead of trains down to a nats arse, using the onboard free running timer on the 7300 to measure the time between counter readings. I read the counter "about" every second using usleep() to wait for the next interval, but use the free running timer to determine the EXACT time between the readings, then calulate the speed.
Go to http://groups.yahoo.com/, sign up for an account if needed, and search the archive for: "free running timer". You might find the answer to other questions this way too.
I used the code posted to the group to make the free running timer work.
Don.
On 7/13/06, Ira Hoffman <> wrote:
Thanks. I couldn't find the pin mapping in the docs.
I am using the XDIO api that is provided...nice job, Michael!
I was wondering how people were tying measurements to accurate timing.
Is there an easy and accurate way to determine the delta t between
counter readings? Is there a better way than using gettimeofday?
-Ira.
On Thu, 2006-07-13 at 14:09 -0700, Michael Schmidt wrote:
> >
> > Also, the manual does not indicate which pin does what function for
> > the quad counter. Any ideas? Which pin is chan a, b, index, etc.
> >
>
> DIO6 and DIO7 are the quadrature counter pins.
> DIO5 is the index pin.
>
> On page 35 of the TS-7300 manual
> (http://www.embeddedarm.com/Manuals/ts-7300-manual-rev1.1.pdf
) there
> is a
> diagram showing the relationship of the DIO pin names (e.g. DIO5) to
> actual
> pins on the DIO header.
>
> This url might be helpful to you in programming the XDIO pins:
> http://www.embeddedarm.com/epc/xdio.htm
>
> > Thanks,
> > Ira
> >
>
> Regards,
>
> Michael
>
>
>
>
>
-- Dr. Don W. Carr J. G. Montenegro 2258 Guadalajara, Mexico +52-333-630-0704 +52-333-836-4500 ext 2930
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