Olin Lathrop wrote:
> Gonzalo Jiminez wrote:
>>> This sounds more like the code protection config bits are getting
>>> set for some other reason.  Can you bulk erase the "wasted" chips?
>>
>> No, it keeps it's program but I can not re write it anymore... :(
>
> Now it sounds like something is wrong with your programmer.  There is
> nothing a properly functioning programmer can do to an F PIC that
> can't be reversed with a bulk erase, which is also something a
> properly functioning programmer should be able to do.

There is a guy on comp.arch.embedded basically complaining of the same
type of problem with a 16F628.  It seems that when he puts a certain
combination in the config bits, it breaks the chip.  I cut and pasted
his post below.

------------------------------------------------------------------------
-------------

I tried to program PIC16F628 Configuration word with x3F10:
Program Memory Protection OFF
Data Code Protection OFF
LVP OFF
BODEN OFF
MCLRE OFF
!PWRTE OFF
WDTE OFF
INTRC osc.; I/O function on both RA6 and RA7
and apparently something broke.  Programming failed at addr x0000
and now the chip cannot be programmed, regardless of the value of
_CONFIG.  That chip and programmer worked fine the day before and
have worked fine for many months.  Programmer diags. show nothing
wrong.  Indeed, I was able to burn other programs into other 628's
- _CONFIG != x3F10 - but one try with that value killed those chips
too.  Subsequently erasing these chips proceeds w/o incident and
programmer tells me they're erased, but they refuse to accept
programming.

I know about the 628's HVP problem regarding RB4 and wired that pin
to Vss through 2K long ago.

I find nothing in the book of words that warns of lethal or unsupported
combinations of _CONFIG arguments.  Did I miss something?

------------------------------------------------------------------------
------------------------------------------

Didn't some of the 'A' model chips shuffle the config bits around, or
reverse their polarity?  I seem to recall seeing something to this
effect somewhere.

michael brown

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