12f629 config settings

[dhouston]

As the PIC is being manufactured, a laser is used to trim the RC components to establish the nominal frequency of the internal oscillator. The final step is to test it and write a calibration offset value to the highest location in memory. The Define OSCCAL instruction fetches that factory calibration value and plugs it into the OSCCAL register.

AS long as you do not erase the value, this can be done each time the chip starts up. The melLabs programmers can be set so the calibration value does not get erased. If it does get erased, you can set OSCCAL by measuring the frequency and inputting the necessary offset. To do this you need to configure for the internal oscillator with clock out.

You should perform the calibration whenever using time critical functions like RS232.

[Dennis]

Thanks again Dave that explains it perfectly :-)

Are there fast methods to determine the oscal as well as the current fuse setting of the pic by command line or otherwise ?

Dennis

[dhouston]

No. The configuration word is only accessible during programming. See section 9.1 of the datasheet.

Why would you need to see the OSCCAL value? Just make sure you have set the programmer so it does not erase the last word and use the Define to load it into the OSCCAL register. It would behoove you to actually read and digest the manual and datasheet before asking so many meaningless questions.