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Haplo
Joined: 06 Sep 2003
Posts: 659
Location: Sydney, Australia
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| Flash... |
 Posted: Thu Dec 18, 2003 6:46 pm |
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| A simple but interesting question...how many times can I rewrite a cell in the flash of PIC16F87x before it fails? The datasheet says 10000 times, but what is the value for a good practice? |
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Steve H.
Guest
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| Posted: Fri Dec 19, 2003 9:22 am |
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| Good practice for a commercial product is not to go over the minimum endurance during the life of the product. If it's a project for you - then go for the max, you can always burn another chip, right? |
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Haplo
Joined: 06 Sep 2003
Posts: 659
Location: Sydney, Australia
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| Posted: Fri Dec 19, 2003 4:34 pm |
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| Thanks. What is the minimum endurance for writing to the flash? Anyone knows the figure? |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Fri Dec 19, 2003 9:36 pm |
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I know that I could probably find it in the datasheet if I were to look  |
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Haplo
Joined: 06 Sep 2003
Posts: 659
Location: Sydney, Australia
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| Posted: Sat Dec 20, 2003 12:54 am |
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I never post any questions here before I make sure the answer is not in the datasheet
Take PIC16F876 for example. Nowhere in the datasheet it mentions the maximum number of writes to the flash. However, in the datasheet of PIC16F876A it says that value is 10,000 for PIC16f876 (and 100,000 for PIC16F876A). Unfortunately it doesn't mention any 'recommended' values anywhere. Anyone out there wo may know about this? Thanks. |
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Gerd
Joined: 15 Dec 2003
Posts: 6
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| Posted: Sat Dec 20, 2003 9:11 am |
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Hi Haplo,
I could never find a minmum or recommended values for PIC's. It is a normally difficult to get valus for most Flash memorys.
In the last years I always used 10% of maximum rating, this is maybe a little overcautious, but it worked for me. |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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| Posted: Sat Dec 20, 2003 9:28 am |
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From the datasheet:
| Quote: |
The PIC16F87X devices do not automatically verify the
value written during a write operation. Depending on
the application, good programming practice may dictate
that the value written to memory be verified against
the original value. This should be used in applications
where excessive writes can stress bits near the specified
endurance limits.
only a full erase of the entire device will disable code
protection.
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Take a look at page 158 of this pdf:
http://www.microchip.com/download/lit/pline/picmicro/families/16f87x/30292c.pdf
Look under the minimum column for Program Flash Memory
[/quote] |
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Haplo
Joined: 06 Sep 2003
Posts: 659
Location: Sydney, Australia
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| Posted: Sat Dec 20, 2003 4:05 pm |
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| Thanks. That value (1000) is the minimum, not the recommended. But I think I'll stick to that. |
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