Joe,
     This is what I don't know how to do. I believe that I can do the=20
rest of it. At least I think I can, I think I can, I think I can.
Thanks,
rich!

On 7/18/2014 3:42 AM, IVP wrote:
>> Do I use a timer or do I setup a set of delay loops
> The simplest way is to let the timer, eg TMR1, free-run and generate
> interrupts which can be counted
>
> 1s at 20MHz crystal is 5,000,000 cycles. Using a 16-bit timer this
> means 5,000,000 / 65,536 =3D 76 overflow interrupts
>
> Plus (5,000,000 - (76 x 65,536)) =3D 19,264 more cycles
>
> A RAM counter is incremented every interrupt, and at the 76th the
> timer is loaded with - 19,264. The next interrupt is the 5,000,000
> count. It will actually be a few less than this as you have to account
> for the time taken to load the value.
>
> You can also take off a few for the s/w to react to that 77th interrupt
> and set/unset the pin
>
> If you used a 19.6608MHz then there would be no need for a load,
> as (19,660,800 / 4) is exactly divisible by 65,536 =3D 75 interrupts
>
> Joe

--=20
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