Re: [ECOS] cyg_flash_program_mask

[Andrew Dyer <amdyer at gmail dot com>]

On Tue, Feb 15, 2011 at 23:46, Andrew Lunn <andrew@lunn.ch> wrote:
> On Tue, Feb 15, 2011 at 12:47:49PM -0600, Andrew Dyer wrote:
>> You have to be very careful doing this. ?At least some NAND flash
>> parts have restrictions on how many 'partial page program' cycles you
>> can do. ?For the part I am using, the restriction is 4 for normal
>> memory pages, and 8 for the one time programmable area.
>
> Hi Andrew
>
> So for the none one-time blocks, after 4 partial writes you need to do
> an erase, before you can do more partial rights? Or are you saying
> only 4 ever?
>
> What part is this?

This is a recent Micron 2Gb large page NAND (I don't have the
datasheet handy, but I believe it was the M60A generation).  The
limitation is that you can do 4 partial writes and then you must do an
erase.

If you search for 'partial page NAND' you'll get a series of hits from
different vendors.  The link below is for a conference presentation
from Micron.  In the section about bit disturb they explain what's
happening to prevent unlimited writing.

http://www.broadbandreports.com/r0/download/1507743~59e7b9dda2c0e0a0f7ff119a7611c641/flash_mem_summit_jcooke_inconvenient_truths_nand.pdf


As another data point, the link below discusses limitations in doing
this with a Spansion NOR multiple bit/cell NOR flash:

http://www.spansion.com/Support/AppNotes/BitFieldProgMirrorBit_AN_A1_e.pdf

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