> >> Upon investigation we found that the only reason for this may be the
> >> internal oscillator inaccuracy
> >
> >Can the oscillators be brought into tolerance by programming different
> OSCAL
> >values yourself, or is the available range totally to one side of the
> >specified frequency?
>
> according to datasheets:
> Adjusting CAL5-0 from 000000 to 111111 yields a higher clock speed.
> Note that bits 1 and 0 of OSCCAL are unimplemented and should be written
as
> 0 when modifying OSCCAL for compatibility with future devices.

Yes, I know how OSCCAL is supposed to work.  You said you got a bunch of bad
chips, and I was wondering whether the problem was that the factory
programmed OSCCAL value was incorrect or that the chips couldn't be made to
oscillate at the correct frequency regardless of the OSCCAL value.

> I guess OSCCAL is just register with set of resistors connected to it's
> outputs, which connetcs in parallel to the main internal resistor for the
> oscillator when '1' is written in the correspondign bit. When you write
'1'
> total resistor value goes lower and increase the frequency.

Possibly.

> Tsvetan
> ---
> PCB prototypes for $26 at http://run.to/pcb (http://www.olimex.com/pcb)
> Development boards for PIC, AVR and MSP430  (http://www.olimex.com/dev)

Do you guys do more than two layers boards yet?  That has kept me from
trying you out a few times now.


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