On Fri, Jul 18, 2014 at 03:47:44AM -0500, Richard R. Pope wrote:
>      Less than 1 percent would be worst case. If 1ppm could be achieved=20
> that would be great but I don't know if that is possible. I'm not going=20
> to use it for calibration work.

But what is your crystal accuracy?

On Fri, Jul 18, 2014 at 04:12:37AM -0500, Richard R. Pope wrote:
> James,
>      My HP gets 1ppb of course I don't expect any thing close to that.=20
> Like I said 1ppm would be great. OK, no resonator. A crystal is no=20
> problem. Timers sound better but more difficult. And it is the timer=20
> that I don't how to setup to get my one second pulse on demand.

A timer is a counter.  Unlike a software counter, it counts by itself.

So your software would load a reset value into the counter, reset the
counter, enable the interrupt, wait for the interrupt, and when the
interrupt occurs generate the pulse.

Some timers have to be reset, some timers have an autoloading reset
value.  The datasheet for the part will tell you.

>      The reset pulse is easy. Just output the high for one or two=20
> instruction cycles. The part that I'm not getting is how to wait for=20
> whatever amount of time that corresponds to the wishes of the user for=20
> the length of time to display the reading. Sometimes when I am using my=20
> HP freq counter I like to have a very fast display refresh. At other=20
> times I want the count to stay up for a much longer time period before=20
> it is refreshed.
>      The reset pulse of 20ns or longer occurs when the display should be=
=20
> refreshed. Then the one second pulse is output to open the count gate.=20
> Now we wait for a certain length of time so that the user can read the=20
> display and then we output the reset pulse and open the counting gating=20
> and do this over and over. But how? I know what I want to do and the=20
> order to do them in but I don't know how. I know that the configuration=20
> fuses have to be set, then setup the ADC, setup the timer or timers, and=
=20
> finally enter the loop. Is that it?

Not sure what you want an ADC for, sorry.  Maybe I missed something.

--=20
James Cameron
http://quozl.linux.org.au/
--=20
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