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'PIC16C74A erasibility after Code Protection'
1997\11\19@143837 by Jim Main

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Can anyone tell me (authoratively) whether the 16C74A is one of the
parts that can't be erased once code protected (UV parts).

Reason I ask is that I can't seem to erase three 16C74A's after my
programmer threw a wobbler and code protected them.

I had a good look at the latest datasheets for the 16C74A and Microchip
don't mention non-erasiblity at all - so what could be the problem??

Any ideas??  Is it just playing hard-to-erase?

Jim
--
Jim Main

1997\11\19@150316 by Santiago

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part 0 988 bytes content-type:text/x-vcard; charset=us-ascii; name="vcard.vcf"In the 123 page of the CD '97, you can see that if the part NO is JW
version, and you have programed the code protention, you can't to erase
this bits.

I sorry.

Regards
Santiago

Jim Main escribi—:
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1997\11\19@155502 by Justin Crooks

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       According to "Pic'n Up the Pace" by David Benson, you've just created
three "rather expensive paperweights"-- I don't know of any way to undo
code protection.  Sorry.

----------
{Quote hidden}

1997\11\19@160949 by Sean Breheny

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At 01:38 PM 11/19/97 -0700, you wrote:
>        According to "Pic'n Up the Pace" by David Benson, you've just created
>three "rather expensive paperweights"-- I don't know of any way to undo
>code protection.  Sorry.

There was a thread some time ago about this and if I recall, some people
said that they were able to erase the part by placing it in the eraser for
a rediculously long time, such as several hours to a day. I've never code
protected a part so I don't know if this is true.

Sean



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1997\11\19@162439 by Matt Bonner

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Jim Main wrote:
>
> Can anyone tell me (authoratively) whether the 16C74A is one of the
> parts that can't be erased once code protected (UV parts).
>
> Reason I ask is that I can't seem to erase three 16C74A's after my
> programmer threw a wobbler and code protected them.
>
> I had a good look at the latest datasheets for the 16C74A and Microchip
> don't mention non-erasiblity at all - so what could be the problem??
>
> Any ideas??  Is it just playing hard-to-erase?

This thread again... :)

MChip's official position is that code-protected devices cannot be
erased.  I have done some playing around and have found that they _can_
be erased.  These are my observations:
1. Some 74As can take many hours to erase (3 or 4).
2. Code-protected parts tend to erase faster if they've been programmed
in the PIC-start plus as opposed to the ProMate II.

My eraser is a 10 year old Spectroline (original tubes).

--Matt

1997\11\19@163035 by Matt Bonner

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I wrote:

> MChip's official position is that code-protected devices cannot be
> erased.  I have done some playing around and have found that they _can_
> be erased.  These are my observations:
>  1. Some 74As can take many hours to erase (3 or 4).
>  2. Code-protected parts tend to erase faster if they've been programmed
> in the PIC-start plus as opposed to the ProMate II.
>
> My eraser is a 10 year old Spectroline (original tubes).
>
I took a quick look back through my notes regarding Point 2: I think
that the ProMate is more vigorous in its blank checking than the
PIC-start plus.  There is no evidence that it programs the device more
"thoroughly".

--Matt

1997\11\19@164537 by ndie Ohtsji [4555]

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I thought the only difference between a "prototype" (PIC-Start Plus) and
a "production" (ProMate) programmer was the verification voltage.
The "prototype" only does a verification at 5VDC while the "production"
verifies at both Vddmin and Vddmax (4.5VDC and 5.5VDC respectfully).

This info is in the programming section of the microchip data sheets for
the part in question.  I only looked at the data sheets for the 16C84 and
16F84 parts.

-Randie
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{Quote hidden}

1997\11\19@170608 by Steve Smith

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You write:-
Can anyone tell me (authoratively) whether the 16C74A is one of the
parts that can't be erased once code protected (UV parts).

Yes its one of them !

However the method of hiding the code protect fuse involves putting an
metalisation layer over it dependant on the thickness of layer determines the
length of time to erase some product will erase if left in the eraser for
several hours. I have personal experance of this left them in the pot for a
weekend and on monday they worked fine. Dont give up just yet .

Cheers Steve.....

1997\11\19@172206 by Matt Bonner

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Randie Ohtsji [4555] wrote:
>
> I thought the only difference between a "prototype" (PIC-Start Plus) and
> a "production" (ProMate) programmer was the verification voltage.
> The "prototype" only does a verification at 5VDC while the "production"
> verifies at both Vddmin and Vddmax (4.5VDC and 5.5VDC respectfully).

You're right.  I can only surmise that what the PIC-start plus thinks is
blank at 5.0V, the ProMate doesn't when it checks the extremes.  BTW,
when the PIC-start plus reports "erased" (and the ProMate doesn't),
apparently the _program_ space is erased because I can program and use
it again.

This is getting confusing - let's go back to what MChip says.  The
device cannot be erased (even though I've done it).

--Matt

1997\11\19@172827 by Jim Main

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In article <KILLspam347358DC.7B0539D5KILLspamspamsunada.com>, Matt Bonner
<RemoveMEmbonnerTakeThisOuTspamSUNADA.COM> writes
>MChip's official position is that code-protected devices cannot be
>erased.  I have done some playing around and have found that they _can_
>be erased.  These are my observations:
> 1. Some 74As can take many hours to erase (3 or 4).
> 2. Code-protected parts tend to erase faster if they've been programmed

Thanks - I'll give them a good soaking!

What's really hacked me off about this is Microchips failure to put this
in the data sheet (although someone said it was on the CDROM - which I
havent got).

Their latest 16CXX data sheet doesn't mention it at all - which I think
borders on the criminal.  It should be up there in bright shiny red 36
point letters...!  ..still I guess it makes them a few more sales..

I'll let you know if I recover them..

Jim

--
Jim Main

1997\11\19@190528 by wwl

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On Wed, 19 Nov 1997 22:18:32 +0000, you wrote:

>In article <spamBeGone347358DC.7B0539D5spamBeGonespamsunada.com>, Matt Bonner
><TakeThisOuTmbonnerEraseMEspamspam_OUTSUNADA.COM> writes
>>MChip's official position is that code-protected devices cannot be
>>erased.  I have done some playing around and have found that they _can_
>>be erased.  These are my observations:
>> 1. Some 74As can take many hours to erase (3 or 4).
>> 2. Code-protected parts tend to erase faster if they've been programmed
>
>Thanks - I'll give them a good soaking!
>
>What's really hacked me off about this is Microchips failure to put this
>in the data sheet (although someone said it was on the CDROM - which I
>havent got).

Yes it is, surely everyone knows that the phrase ;
"Note : Microchip does not recommend code-protecting windowed
devices"
really means
"WARNING ! You will probably never be able to re-use them",
don't they ? It's even printed in a nice shaded box, just so you know
they mean it!  :-)  


>Their latest 16CXX data sheet doesn't mention it at all - which I think
>borders on the criminal.  It should be up there in bright shiny red 36
>point letters...!
>  ..still I guess it makes them a few more sales..
Maybe, but I suspect incompetence rather than marketing reasons - look
at all the bugs they put in their apnotes especially to teach people
PIC programming the hard way by finding them all :-)
>I'll let you know if I recover them..
>
>Jim

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1997\11\19@235507 by tjaart

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Matt Bonner wrote:
>
> I wrote:
>
> > MChip's official position is that code-protected devices cannot be
> > erased.  I have done some playing around and have found that they _can_
> > be erased.  These are my observations:
> >  1. Some 74As can take many hours to erase (3 or 4).
> >  2. Code-protected parts tend to erase faster if they've been programmed
> > in the PIC-start plus as opposed to the ProMate II.
> >
> > My eraser is a 10 year old Spectroline (original tubes).
> >
> I took a quick look back through my notes regarding Point 2: I think
> that the ProMate is more vigorous in its blank checking than the
> PIC-start plus.  There is no evidence that it programs the device more
> "thoroughly".
>
> --Matt

I think the Promate gives the locations more 'hits' than the Picstart +
when programming. The blank checking is the same on any programmer.

Because it is the programming rather than the erasing that degrades the
parts, I rather use a Picstart + on the expensive JW's.

--
Friendly Regards

Tjaart van der Walt
tjaartEraseMEspam.....wasp.co.za
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1997\11\20@105838 by Matt Bonner

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Tjaart van der Walt wrote:
> I think the Promate gives the locations more 'hits' than the Picstart +
> when programming. The blank checking is the same on any programmer.
>
> Because it is the programming rather than the erasing that degrades the
> parts, I rather use a Picstart + on the expensive JW's.

The makes sense.  I have my PICstart Plus hooked up to my development PC
and the ProMateII attached to a DOS machine for production programming.
The windowed parts which I had the most trouble erasing (I persevered
and they finally _did_ erase), were ones that I had to recall from the
production department due to the last-minute discovery of a bug. :-0

The code-protected JWs made on my development PC took maybe an hour to
erase.  The parts from the ProMate took about 4.

--Matt

1997\11\20@144157 by Ian Cameron

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I have four 16C63 JW devices, and three of them are now in a state
where my PicStart + says the configuration bits are not blank.

Two of them were programmed for code protection, and another one
seemed to go after I experimented with ISP for the first time...

I tried leaving these in a UV eraser for ages, but I still can't get
them blank.  I think the tube was probably too weak though, as it
eventually went *really* dim in the end.  I was resting this handheld
eraser on a bit of sheet metal, and now there's a nice shadow where
the PIC's were sitting, surrounded by a light patch where the plastic
coating on the metal was exposed :-]

The tubes on the other eraser which I usually use (a drawer type)
must be a bit low too, since people on this list have said in the
past that 5 mins should erase a JW part, but it always took about 15
mins for me...

Maybe if I can get the UV tubes replaced, I will eventually get these
parts going again ?

Cheers, Ian.

1997\11\21@143819 by Robin

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>
>MChip's official position is that code-protected devices cannot be
>erased.  I have done some playing around and have found that they _can_
>be erased.  These are my observations:
> 1. Some 74As can take many hours to erase (3 or 4).
> 2. Code-protected parts tend to erase faster if they've been programmed
>in the PIC-start plus as opposed to the ProMate II.
>
>My eraser is a 10 year old Spectroline (original tubes).

I have erased a protected 16C64 (or 65?) in max 30 minutes (if I remeber right).
My programmer is a PIC-Start and the eraser was a Spectroline PE-140T/F.

ciao from Italy

Roberto Marchini
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1997\11\22@041612 by Jim Main

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In article <EraseME199711211901.UAA28313spaminrete.it>, Robin <RemoveMErobinEraseMEspamEraseMEINRETE.IT>
writes
>>
>>MChip's official position is that code-protected devices cannot be
>>erased.  I have done some playing around and have found that they _can_
>>be erased.  These are my observations:
>> 1. Some 74As can take many hours to erase (3 or 4).
>> 2. Code-protected parts tend to erase faster if they've been programmed
>>in the PIC-start plus as opposed to the ProMate II.
>>
>>My eraser is a 10 year old Spectroline (original tubes).
>
>I have erased a protected 16C64 (or 65?) in max 30 minutes (if I remeber
right).
>My programmer is a PIC-Start and the eraser was a Spectroline PE-140T/F.
>

Umm - it's now been over 24 hours in the eraser, and all three 74A's are
still protected...

The chips I have are all rev B - could the protection have been stepped
up between revisions?

Either that, or my eraser's not strong enough (Stag SE1T 15W tube).

Jim

--
Jim Main

1997\11\24@121456 by engelec

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Ian Cameron wrote:

> I have four 16C63 JW devices, and three of them are now in a state
> where my PicStart + says the configuration bits are not blank.
>
>

There are a few more things left to try before replacing the tube.1. if
you have variable transformer make ac 110 to ac130. this is for old tubes
only
2. make sure pic window is sitting right under the uv light
3. put ideational lens top of pic window

if still did not erase in 4-5 hours then replace the unit get more
powerful one.

Andre.

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