Problem on programming 16F506

[brutus]

Hi,
I've read a thread ( http://www.ccsinfo.com/forum/viewtopic.php?t=43815 ) about some problems with 16F506. I have the same problem: at the address 0x3FF I get 0x00, and while programming I get this message in MpLab:

ICDWarn0044: Target has an invalid calibration memory value (0x0). Continue?

According to me is a problem connected with the internal oscillator.
Does anyone knows what shoul be the right value at the address memory 0x3FF value?

I'm using MpLab IDE 8.60 + ICD2 or PIKkit3

Any suggestion?

Thanks,
C

[Ttelmah]

For the calibration value, There is no 'right value'. It varies from chip to chip.

This value is programmed at the factory, and _must_ be read from the chip, and written back each time the chip is programmed. Page 22 in the data sheet. Programmers normally have an option to 'preserve calibration value' (or some similar wording), that does this automatically.

Unfortunately, if you program a chip _without_ using this option, the value will have been destroyed.

Some programmers (Mach-X for example), have an option to calculate the value for you. They load a value, test how fast the clock runs, then adjust the value to get the speed right. Otherwise, you are going to have to do this yourself. Start with 0x0c0000, which will set the chip to it's centre frequency. Then test using a stopwatch and a long delay, and adjust the last two bytes to increase of decrease the frequency.

Best Wishes

[brutus]

Thanks,
I supposed it. I'm not sure why it was 0. In any case for me is not important a perfect calibration, in my application I don't need a great precision.
The problem is that also setting it to a default value (0x0c0000) it doesn't seem to work at all...the oscillator seems blocked.

Claudio.

[PCM programmer]