>
> Please can anyone tell me if windowed PIC's can be erased by any old UV
> eraser, or do they need something particularly powerful?
>
> Is it easy to damage a windowed PIC in such a way that it cannot be
> erased?
>
> Thanks,
>
> Richard D.
>I don`nt think that a old erease can damage the pic.
>You can`t erase the pic, if the pic was protected, when was programated
>Francisco
>"Richard D." wrote:
>
> Please can anyone tell me if windowed PIC's can be erased by any old UV
> eraser, or do they need something particularly powerful?
>
> Is it easy to damage a windowed PIC in such a way that it cannot be
> erased?
>
> Thanks,
>
> Richard D.
Some PIC's (not all) apparently have the protect shielded from the UV so they
cannot be reprogrammed if you do erase them. These ones can certainly be erased
however, they just become useless because you cannot reprogram them.
I think you will find that to erase any UV erasable chip you will need a
fluorescent tube with no filter on it. The ones used for "black light" for
checking banknotes and the like have the required UV for erasing filtered out.
It is easy to damage a PIC so it is erased so it cannot be programmed - leave it
in the sun for a while on a summers day! I had an EPROM where this occurred, and
the shape of the window was such it became a lens and focussed the suns rays
onto the chip and destroyed it. The other way to destroy chips is to use the
wrong programming voltage, or put the voltage on the wrong pin.
> Yeah, it's trivially easy: To render a newer PIC unerasable,
> just enable its Code-Protection.
Nit: that doesn't make it unreasable, more like un-reprogrammable. A UV
eraseable part with the code protect set becomes useless (even for its
original purpose) in a UV eraser, rather than staying unerased.
<x-flowed>Why is that, why will the pic become useless after code protection, who
would like to do such a thing with a uv erasable pic? I can't see anything
positive with that, if you program it and by an accident enables the code
protection then your expensive pic is lost... Did Microchip plan that when
they constructed the chip?
>From: William Chops Westfield <billwKILLspamCISCO.COM>
>Reply-To: pic microcontroller discussion list <.....PICLISTKILLspam.....MITVMA.MIT.EDU>
>To: EraseMEPICLISTspam_OUTTakeThisOuTMITVMA.MIT.EDU
>Subject: Re: Erasing PIC's
>Date: Fri, 12 May 2000 12:43:22 PDT
>
> > Yeah, it's trivially easy: To render a newer PIC unerasable,
> > just enable its Code-Protection.
>
>Nit: that doesn't make it unreasable, more like un-reprogrammable. A UV
>eraseable part with the code protect set becomes useless (even for its
>original purpose) in a UV eraser, rather than staying unerased.
>
>BillW
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> Why is that, why will the pic become useless after code protection,
> who would like to do such a thing with a uv erasable pic? I can't
> see anything positive with that, if you program it and by an
> accident enables the code protection then your expensive pic is
> lost... Did Microchip plan that when they constructed the chip?
Johan:
Yes, Microchip planned it that way. In their older PICs, the copy-
protect bit was erasable, which allowed unscrupulous people to defeat
the code-protection. The newer PICs shield the code-protection
memory cells from UV in order to prevent that.
Windowed and non-windowed PICs contain the same silicon, so Microchip
can't make "development" versions of the PICs that don't contain that
copy-protection feature.
Does that mean if you "pry" the top off an OTP,
you'd see a uv part in the middle? Not that all
the wirebonds would hold, but you'd see the UV
EPROM, right?
> Does that mean if you "pry" the top off an OTP,
> you'd see a uv part in the middle? Not that all
> the wirebonds would hold, but you'd see the UV
> EPROM, right?
>
> -W
>
> {Original Message removed}
MITVMA.MIT.EDU> wrote:
