Sean Alcorn - Avion SYD wrote:
>
> Hi guys,
>
> Well I've achieved my next milestone. I keyed in a few lines of code
> today and had an LED flashing nicely at approximately 1Hz.


Me too :-)

 However just
> as I hit the program button, I realised I may have done one thing
> wrong. I did not open the Program/Verify window of MPLAB. If I had, I
> would have noticed that "Calibration Memory" was checked.
>
> I know this is bad news for a JW Part - unless you record the factory
> setting. Does this apply to EEPROM parts also?
>
> The data sheet says;

I've got my programmer working with these things, and the spec says to
read OSCAL abd bangap values before erasing and restore them afterwards.
The programmer is responsible for maintaining the data, although it
would be wise to read these and store them just in case.

> Also, writing to the OSCCAL register appears to be different to the
> PIC12C508 and PIC12C671 parts. The data sheet now says;
>
> bsf     STATUS, RP0     ;Bank 1
> call    3FFh            ;Get the cal value
> movwf   OSCCAL          ;Calibrate
> bcf     STATUS, RP0     ;Bank 0
>
> Am I mistaken, or did the PIC12C508 and PIC12C671 basically powerup at
> the end of it's memory and effectively do a movlw   [calibration value]
> - then your first instruction simply needed to be a MOVWF   OSCCAL -
> did it not?

The 12C50x powers up at last memory, the 12C6xx at first.

12C50x has movlw OSCCAL
12C6xx has retlw OSCCAL

> It's interesting that there is no Window > Calibration Data option when
> I have PIC12F675 selected in MPLAB v5.70.40, however when I change to
> any of the 12C series, I can open a dialogue box called "Calibration
> Contants" by selecting Calibration Data from the Windows menu. How is
> is possible to read (and therefore record) the factory set calibration
> data for a PIC12F675 or is it simply not necessary?

Just read the chip. and note the data.

--
Best regards

Tony

mICros
http://www.bubblesoftonline.com
mailto:sales@bubblesoftonline.com

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