Re: [avr-chat] 32768 Hz clock

[Vikas Yadav]

At 512 interrupts per second when you chip clock is at 1mhz (the lowest) might loose interrupts while processing the IVR. Also, in the IVR you cannot calculate the time! just modify the seconds global variable and let your infinite loop in your primary thread do the calculation and even rendering to LCD or 7 segment. IVR has to be light weight in order to provide maximum performance.

My first clock was sampling enough to only call my IVR every second. i don't even need to be called faster than that!

I certainly wish to know how to get a millisecond precession though but the sampling bits don't allow me to do so i suppose.

Regards,

Vikas

Royce Pereira wrote:

Hi Bill,

I did try your suggestion of overflowing TCNT2 & dividing the interrupts by 128, and it worked!
But like you said without the caps, there is an error of 1 sec/hour.

So- what are the recommended values of capacitors to be used?

Many Thanks,

--Royce.

On Sun, 23 Apr 2006 05:49:21 +0530, Bill Rochat <address@hidden> wrote:

claims that you don't need external capacitors when ASSR is selected,
however, without them, there is a time error of about 1 second each hour.

I notice that you interrupt 512 per sec.  Any particular reason??  I just
let the counter overflow TCCR2=0x08. That occurs 128 per sec.

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