Roman,

Your 1 sec timer code is really cool. I think I'd better be off using a
modified
version of your code rather than mess around by directly loading values into
the TMR0 reg.

My application is for a "Smart" UPS based on 16f877 using its PWM output.
So, if it is to work as planned, it must execute the target routine 3200
(50Hz * 2 * 32 times) times.

Won't the Interrupt being called so very often (every 256 cycles)
severely reduce the MIPS available to Non ISR Code ?
I know this is quite a wierd question. But I just asked it out of curiosity.

So as per the calculations given in your page,
Xtal_Freq = 2,000,000 Hz (20 Mhz)
reqd_Freq = 3200 Hz
Therefore, the 24bit value = 1562 (.5 ignored)
(Am I right with it ?)

And can you please tell me a straightforward method to calculate the jitter
?


Thanx a lot!

Jeethu Rao


-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Roman Black
Sent: Saturday, June 23, 2001 1:37 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC]: Timer0 Interrupt Timing


Jeethu Rao wrote:
>
> Vasile,
>         I almost understood your method, but where does the Prescaler
value go?
>         You did'nt write anything about that. Could you please tell me a
more
>         refined version of your algorithm to find out the TMR0 period ?
>
> Thanking you,
> Jeethu Rao
> www.jeethurao


Hi Jeethu, I put the whole procedure and complete
code samples up on this web page:

http://centauri.ezy.net.au/~fastvid/one_sec.htm

The code will run as it is, flashing a led, and
the prescaler setup is clearly shown.
:o)
-Roman

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