Re: [ts-7000] Re: T3 timer use on TS-7200

You need to be able to catch the interrupt from the timer when it expires. The only way is with a driver of some kind. Polling the timer registers is not reliable especially if the countdown is very short.

--- On Mon, 7/27/09, tseredynski <> wrote:

From: tseredynski <>
Subject: [ts-7000] Re: T3 timer use on TS-7200
To:
Received: Monday, July 27, 2009, 2:22 PM

 

Hi,

Thanks for the response. Why exactly do I need to use a kernel driver? I'm not very familiar with them, and I don't usually like to use things that I don't understand well. I'm currently trying with T4 instead of T3 and it's showing more promise of being reliable... but I'm not done yet.

But I'd really like to know why I'm unable to make use of the timer with pure C programming. Thanks.

--- In .com, Jim Jackson <> wrote:
>
>
> You really need to use a kernel driver for this.
> For an example, check our Phil's ADC kernel module - it's in the file
> section of the group. It uses one of the timers to schedule when to
> read the ADC.
>
> On Fri, 24 Jul 2009, tseredynski wrote:
>
> > Hello,
> >
> > I'm trying to use the T3 timer on my Ts-7200 to execute a function at a constant 4khz rate (every 0.25 ms), but I'm running into trouble.
> >
> > I'm trying to do so by loading the appropriate value to the timer, and then constantly polling the T3 value, and waiting for it to hit 0. However, a few problems occur. First of all, it doesn't seem like my program can poll the value fast enough to catch the 0. The clock hits zero, and resets before my program can even get the value.
> >
> > It also seems that every couple of milliseconds (~5ms) I get a large delay. I checked this part by using printf() to display values as fast as it could and I'd usually get gaps of about 20 clock counts, however every couple of milliseconds I'd get a gap that was much larger (a couple hundred clock counts). Also, while trying to print values as fast as possible, it would usually print 20 values per cycle but every couple of cycles it would print closer to 30.
> >
> > This makes me think that there might be processes running on the board with higher priority than my program.
> >
> > Does anyone have some advice? Can I use the timer like I'm trying to, or do I need to try to use the interrupt request generated by the timer? (I don't know how to do this atm, so advice regarding that would be appreciated)
> >
> > Thank you!
> >
> >
>

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