Lpc2000

Hi Al,

even changing some bits from 1 to 0 would generate a wrong reading.
The LPC2000 devices have an error correction  ECC mechanism build in.
 This is part of the flash and will be written the first time (after
erasing) the block of 128-bits is programmed. Any changes thereafter
will result in reading garbage because the ECC mechanism will try to
correct anything changed after the initial write.

The idea was to write one 128-bit block after the other, NOT writing
the same 128-bit block several times. This is possible 16 times within
a 4k block. So 16 writes to 16 different sections of 128-bit each
within a 4k block, then erase the 4k block.

Hopefully this clarifies this issue a little more. 


--- In lpc2000@yahoogroups.com, onestone <onestone@b...> wrote:
> Flash bits can only be written to '0'. They erase to a '1' state. 
> Therefore unless you are only changing a couple of bits to '0' you MUST 
> erase flash everytime before reprogramming it.
> 
> Al
> 
> Leighton Rowe wrote:
> 
> > 
> > Concerning Philips Apps' post on Partial Flash Programming I
> > understand lpc flash memory can be updated 128 bits (minimum) at a
> > time, and that a each 4K area can be written 16 times (max).
> > 
> > (http://groups.yahoo.com/group/lpc2000/message/2681)
> > 
> > However, I'm currently having trouble updating 128-bit (quadword
> > aligned) locations in flash memory. The first write always
> > show up OK (as long as the location has all 1's), but on the 2nd
> > write (on the same location) results in some bit(s) not displaying
> > correctly.
> > 
> > Is it possible for me to re-write a 128-bit (quadword aligned) flash
> > locations? Or must I erase the flash location first? I can do the
> > second question, but I'm a little confused about how often flash
> > bits can change without an erase.
> > 
> > best regards,
> > Leighton
> > 
> > 
> > 
> > 
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