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'[PIC]: How to erase 12c508a??'
2001\01\26@095822 by Mg

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Hello Pic-rs!
Anyway to erase a 12c508A?? Some other numbers on the chip are 04/PHBW and
9915.

The reason I'm asking is I've got a few of these little fellas. I've
programmed 2 of them, needed to change the code on one of them, and the
erase command is greyed out, ie: i cant use it. I'm using the September 2k
release of P16PRO and I've also tried to use the latest version of PICALL,
(I have a parallel programmer). The erase command is greyed out for all
12c50X devices... can't any of these devices be erased??

I read about Microchips OTP devices but I would have thought that Microchip
would release some flash 12c50X? - ie: erasable 12c50X devices..

I bought my 12c fellas under the impression I could erase them! I debug code
by trial and error - code the chip, wack it in the circuit, and see if it
works..

I'm fully thinking I've missed something here..<GRIN>

Thanks guys!
-Mg

PS: The piclist has been my night time reading for many many months now! And
no I don't mean it helps me to fall asleep! :) I've finally broken my
silence! yeehaa!

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2001\01\26@100700 by Martin Hill

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Hi Mg,
 As far as I know there are no flash 508 parts, if there are, they will
be a 12F508.  I also do my development in the same way.  What
you need is the windowed part /JW which can be erased using UV.
Be careful to note the calibration value stored in the chip before
erasing.  If your part doesn't have a window then they are otp I'm
afraid.  I used to use windowed 16C76, then changed to 16F876
flash parts.  Soooo much quicker, also means I can solder onto the
board and just use the icsp.

Martin

{Quote hidden}

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2001\01\26@100717 by Bob Ammerman

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The PIC 12C508A is OTP unless it is a "JW" package type.

OTP == One time programmable.

Time to go buy some more chips. You'll need the $$$ "JW" type for
development.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

{Original Message removed}

2001\01\26@133728 by Olin Lathrop

face picon face
> Anyway to erase a 12c508A??

Not unless it's a UV erasable part.  These end in a JW suffix and have a
very obvious quartz window.


*****************************************************************
Olin Lathrop, embedded systems consultant in Devens Massachusetts
(978) 772-3129, .....olinKILLspamspam.....embedinc.com, http://www.embedinc.com

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2001\01\26@153259 by uter van ooijen & floortje hanneman

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> > Anyway to erase a 12c508A??
>
> Not unless it's a UV erasable part.  These end in a JW suffix and have a
> very obvious quartz window.

Grind the plastic top layer away (without hurting the die or the wires) and
make your own el-cheapo JW?

More serious: to conserve time-consuming erase-cycles (and to reserve a
second life for OTPs) when you have an application that takes only a small
part of the code area note that the erased state is al 1's (XORLW 0xFF) and
that all 0's is a NOP. So start with

goto application
xorlw 0xFF
xorlw 0xFF
 xorlw 0xFF
xorlw 0xFF
xorlw 0xFF
xorlw 0xFF
application:

Next time, replace the goto by a NOP and the first xorlw by a goto
application, where your application starts juts beyond the previous
application.

Wouter

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2001\01\26@183432 by mike

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On Sat, 27 Jan 2001 00:49:46 +1000, you wrote:

>Hello Pic-rs!
>Anyway to erase a 12c508A?? Some other numbers on the chip are 04/PHBW and
>9915.
>
>The reason I'm asking is I've got a few of these little fellas. I've
>programmed 2 of them, needed to change the code on one of them, and the
>erase command is greyed out, ie: i cant use it. I'm using the September 2k
>release of P16PRO and I've also tried to use the latest version of PICALL,
>(I have a parallel programmer). The erase command is greyed out for all
>12c50X devices... can't any of these devices be erased??
No.
>I read about Microchips OTP devices but I would have thought that Microchip
>would release some flash 12c50X? - ie: erasable 12c50X devices..
There's no point  - they do windowed UV-eraseable JW parts for
development. As the 12C's are aimed at high volume ultra low-cost
apps, most of which are unlikely to require field updates, the extra
cost of doing a flash version  isn't justified.
>I bought my 12c fellas under the impression I could erase them! I debug code
>by trial and error - code the chip, wack it in the circuit, and see if it
>works..
>
>I'm fully thinking I've missed something here..<GRIN>
Yes - you should have bought a couple of JW parts!
>Thanks guys!
>-Mg
>
>PS: The piclist has been my night time reading for many many months now! And
>no I don't mean it helps me to fall asleep! :) I've finally broken my
>silence! yeehaa!

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2001\01\27@020536 by Mg

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Thanx everyone for your help!
It would benefit me to have a 12f508 on the market. I wouldnt have to bother
about UV erasing the thing and I would develop the code on the flash part
and then use an OTP part for the final device. Or I could just emulate the
code first, modify it, wack it on a 16f84, see if it works and then wack the
code on the OTP device. Hmmm I can hold my breath and wait/hope for a 12f508
or I can do the latter!

Wouter: Just for the sake of it (ie: killing time), I'll try converting it
to a JW part tonight! If it works I'll put my entry in for the lotto! Will
exposing the internals of the chip wreck it, as in exposure to air?
The last method of yours is quite a good idea!

Thanx again everybody!
-Mg
{Original Message removed}

2001\01\27@094246 by mike

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On Sat, 27 Jan 2001 17:07:00 +1000, you wrote:

>Thanx everyone for your help!
>It would benefit me to have a 12f508 on the market. I wouldnt have to bother
>about UV erasing the thing and I would develop the code on the flash part
>and then use an OTP part for the final device. Or I could just emulate the
>code first, modify it, wack it on a 16f84, see if it works and then wack the
>code on the OTP device. Hmmm I can hold my breath and wait/hope for a 12f508
>or I can do the latter!
>
>Wouter: Just for the sake of it (ie: killing time), I'll try converting it
>to a JW part tonight! If it works I'll put my entry in for the lotto! Will
>exposing the internals of the chip wreck it, as in exposure to air?
Air exposure  is OK, but the main problem is getting that last bit of
plastic off without also taking the top off the silicon, or breaking
the bond wires. A chemical approach would probably be better.

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2001\01\27@103118 by dre Domingos F. Souza

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>Grind the plastic top layer away (without hurting the die or the wires) and
>make your own el-cheapo JW?

       And use a 2-mega-bucks microscope to see if you have brushed the die? :o)

>More serious: to conserve time-consuming erase-cycles (and to reserve a
>second life for OTPs) when you have an application that takes only a small
>part of the code area note that the erased state is al 1's (XORLW 0xFF) and
>that all 0's is a NOP. So start with

       Better: Build an ICD.


--------------8<-------Corte aqui-------8<--------------

       All the best!!!
       Alexandre Souza
       KILLspamxandinhoKILLspamspaminterlink.com.br
       Linux User #85093

--------------8<-------Corte aqui-------8<--------------

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2001\01\27@110936 by Bob Ammerman

picon face
> Thanx everyone for your help!
> It would benefit me to have a 12f508 on the market. I wouldnt have to
bother
> about UV erasing the thing and I would develop the code on the flash part
> and then use an OTP part for the final device. Or I could just emulate the
> code first, modify it, wack it on a 16f84, see if it works and then wack
the
> code on the OTP device. Hmmm I can hold my breath and wait/hope for a
12f508
> or I can do the latter!
>
> Wouter: Just for the sake of it (ie: killing time), I'll try converting it
> to a JW part tonight! If it works I'll put my entry in for the lotto! Will
> exposing the internals of the chip wreck it, as in exposure to air?
> The last method of yours is quite a good idea!

Chips are encapsulated to protect them from damage caused by the slow
infiltration of contaminants. If you manage to open up the chip without
physically damaging the lead frame, bonding wires or die it will probably
work, for a while at least.

Anybody's guess on the definition of 'a while'.

Bob Ammerman
RAm Systems
(contract development of high performance, high function, low-level
software)

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2001\01\27@112559 by Spehro Pefhany

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At 11:05 AM 1/27/01 -0500, you wrote:

>Chips are encapsulated to protect them from damage caused by the slow
>infiltration of contaminants. If you manage to open up the chip without
>physically damaging the lead frame, bonding wires or die it will probably
>work, for a while at least.

Decapsulation can be done fairly easily, it involves some nasty chemicals
that are not available at retail. If anyone is interested, a web search
will yield some procedures. There are also small machines that will do
this automatically. The cost of the chemicals would probably be about
$100 from a lab supply outfit, and there would be hazmat shipping and
disposal considerations.

>Anybody's guess on the definition of 'a while'.

I don't think there would be any problem, at least in a dry environment.
The chip itself is passivated with a glass layer, so its only the aluminum
bonding wires to worry about corrosion on.

Best regards,

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2001\01\27@130814 by rottosen

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Bob Ammerman wrote:
{Quote hidden}

Many (!) years ago our company's product used many fusible link PROMs.
Did I say it was a long time ago?. As is normal, the design changed and
these one-time-programmable parts became worthless. They of course were
still good. We removed the metal lid of one by filing it off. This left
the bond wires and die completely undamaged. Every once in a while we
would take the opened part and compare its program to an unopened part.
We did this for months and every time the part was still good. We must
have lost interest before the opened PROM failed because I don't
remember it ever going bad.

Because of our success with the PROM, we decided to open a CCD shift
register digital memory chip. Once the chip was open, we plugged it into
a system to see if it still worked. This chip was used in a TV image
memory so we were able to shine light on the chip and see changes in the
picture!

Next, we decided that we wanted to see the insides of a Motorola MC6800
microprocessor. Most of the parts we had were in plastic packages and
couldn't be opened. One of the engineers had a sample in his drawer that
he used as a test replacement when he suspected a bad microprocessor.
This part was in a metal lidded ceramic package. We convinced the owner
that he could no longer trust part since he had used it so much. :-)

We opened it up and passed it around for everyone to admire. After it
had been oohed and aahed over by many people, someone suggested that we
plug it into a circuit to see if it still worked. It didn't. :-(
It was pointed out that with all the handling that maybe one of the bond
wires had been damaged. So, one of the technicians looked at the part
under a stereo microscope. He saw 2 bond wires bent and shorted
together. He then proceeded to use a stripped 30ga. wire-wrap wire as a
crowbar to straighten out the damaged bond wires!

When we put the repaired chip back into the circuit it still didn't
work. :-(  But wait... It was exposed to the room lights. When we cast a
shadow over the die it DID work!

Is this a detailed enough answer for you Bob???


-- Rich




>
> Bob Ammerman
> RAm Systems
> (contract development of high performance, high function, low-level
> software)
>
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2001\01\28@171017 by Tony Nixon

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picon face
Mg wrote:
>
> Thanx everyone for your help!
> It would benefit me to have a 12f508 on the market. I wouldnt have to bother
> about UV erasing the thing and I would develop the code on the flash part
> and then use an OTP part for the final device. Or I could just emulate the
> code first, modify it, wack it on a 16f84, see if it works and then wack the
> code on the OTP device. Hmmm I can hold my breath and wait/hope for a 12f508
> or I can do the latter!

Future products guide lists the 8 pin 18F0x0 and 18F0x2 chips - based on
the 18Cxxx series - upto 10 MIPs. I've already got something in mind -
when they arrive??

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Tony

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