Difference 12c674 12ce674

Hi NG,

does anyone know whats the difference between these two PIC processors. I can't find any info about the 12c674 on Microchip's website, but i have both of these.... There must be a difference in the configuration word, since 12ce... programs correctly, but 12c... programs, but is codeprotected afterwards.

BTW: the missing "e" 12c674 might imply that the 12c674 does not have EEPROM memory on chip, but in fact it has, and it's working!

Thanks a lot, Wolfgang

Reply to
Wolfgang Mahringer
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No, it isn't.

Sorry, should have mentioned i talking about windowed devices....

My programmer complains about not erased devices.

Thanks, Wolfgang

Reply to
Wolfgang Mahringer

You need to erase the device with a UV eraser. see google "UV eraser" The CE just means it has EEPROM, make sure you save the Oscillator Calibration Value before you erase it!!

Phil

Reply to
Phil

Sorry Phil, you missed the point.

I have two chips, one 12C674 and one 12CE674, both in windowed DIP package. Programming works fine with the CE type, the C can be programmed and verified, but as soon as the configuration word is programmed, the device is code protected. Thats why I think, there must be a difference in the config bits.

Both devices definitely *have* EEPROM on chip. I tried to access it (it works fine on both), and on the windowed devices you can actually *see* the extra chip through the window.

The Microchip Homepage does not show a 12C674 type, only 12CE674.

Greetz, Wolfgang

Reply to
Wolfgang Mahringer

For a resistor, if it doesn't fit within the 1%tolerance, it goes into the

2%, and if it fails the 2% it goes into the cheaper 5% bin.

For a CPU, if it fails to run at 8mhz, it may qualify okay as a 4mhz CPU.

The C and CE may be the same, but the C did not meet all the specs of the CE, therefore it got downgraded to only qualifying as C.

This is just a reasonable guess so don't take it as fact. ;-)

Reply to
Amused

Hmm I recall that behaviour on some old 16C74.

On that 12C674, after UV erasure all program memory bytes read FF and after programming ONLY the program memory, I CAN read back the correct code. It is only after setting the config word, that all bytes read as 00. Very weird. Maybe this chip is defective anyway.

Thanks, Wolfgang

Reply to
Wolfgang Mahringer

OK, but then Microchip would list these device numbers, wouldn't they?

Greetz, Wolfgang

Reply to
Wolfgang Mahringer

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