Lpc2000

I'm in a similar boat as I'm porting code from an environment where I
 keep pointers into a flash buffer in EEPROM.  I double buffered the pointers
 so that the unit could survive random poweroffs and pick up where it left
 off.  On the LPC with only flash this is not acceptable due to:
  o erase is on a sector basis which on the 2138 is 4K or 32K
  o it takes 400ms to do an erase which you don't want to do every second
 I looked over the Philips program and also found some useful references:
  http://groups.yahoo.com/group/lpc2000/message/2681
  http://groups.yahoo.com/group/lpc2000/message/8586
 I'm not using the Philips code but it acted as another reference.  There is
 no getting around the physical constraints of the LPC flash but it is good
 to know what you can do with it.  In my case I need to write 32 bytes
 of data every second.  Even tho the spec sheet says 256 bytes is the minimum
 you can still play around inside that and the details are in the above messages.
 For me to write 32 bytes, I copy out 256 bytes aligned to a ram buffer, change
 the 32 bytes I want to record (must be all FF's to do this) and then write back
 the 256 bytes.  Only the 32 bytes I changed are affected in the flash.  To get
 around using pointers into the flash,  I'm using a sentinal marker every 4K
 bytes that has a unique sequence number.  So upon bootup, I scan through
 the flash looking for the sentinel markers and take the latest one and scan
 forward for empty flash and then start there.  As I'm recording in wraparound
 fashion, if I get to the end of a sector, then I erase the next sector for the next
 second.  From the end of flash I wrap to the beginning of the flash space I'm
 using.  I also need to reserve an area of Flash for keeping boot parameters
 but those change infrequently so I can just keep a 4K block for that purpose
 (even though I need less than 100 bytes of config data!).

 Rob

--- In lpc2000@yahoogroups.com, "shergtu" <shergtu@...> wrote:
>
> --- In lpc2000@yahoogroups.com, "Bruce Paterson" <bruce.paterson@> 
> wrote:
> 
> > Woah, haven't heard of that one !  The Philips example (in the files
> > area) to emulate Eeprom using flash has the potential to do many 
> many
> > writes (marching onwards through the flash) without an erase. Where 
> did
> > you find out that information ? Certainly the Philips program should
> > have a re-programming counter if this is indeed the case. Can
> > phillips_apps (Robert) confirm ?
> > I haven't experienced any issues so far with many reprograms without
> > erase on the lab units. (Field units at present would typically not
> > experience many changes).
> > 
> > Cheers,
> > Bruce
> 
> Bruce,
> 
> Wow, I didn't even realize until now there was sample code along 
> those lines (EEPROM emulation).  I just downloaded the .zip file & 
> will take a look.
> 
> When I get to the point where I have some interesting/meaningful 
> results of my own to report, I'll post back to the group.
> 
> Thanks,
> Dan
>