Shop OBEX P1 Docs P2 Docs Learn Events
any free space in the propellers EEPROM I can use? — Parallax Forums

any free space in the propellers EEPROM I can use?

PotatoPotato Posts: 18
edited 2010-02-17 00:53 in Propeller 1
Is there an area in the 24LC256 on board Propeller EEPROM which I may use for small amount of data storage?

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2010-02-16 06:27
    The Spin compiler / assembler allocates memory from location zero upwards. When the program is running in hub RAM, the stack starts at the end of the program and goes upward. Everything from the end of the program to the end of the 1st 32K of EEPROM is set to zero when a new program is downloaded to EEPROM. Generally it's safe to use the end of the 1st 32K of the EEPROM for data storage between program downloads. If you need for data to survive past program downloads, you'll have to replace the 24LC256 with a larger EEPROM like a 24LC512. In that case, the 2nd and subsequent 32K segments are unaffected by program downloads.
  • MagIO2MagIO2 Posts: 2,243
    edited 2010-02-16 12:39
    You can use the .... is it called "view info" ... in the propeller tool. If you view info for the top object, it shows you how much memory-space is used by the whole program. There are red and yellow sections which are needed and the blue one filled up with zeros is the stack area. The same address in EEPROM can be considered as free to use memory. But you should use it top down, because with each change you might have to move the pointer if you use it bottom up.
  • localrogerlocalroger Posts: 3,452
    edited 2010-02-16 13:01
    It's F8. Don't forget you do need to leave some room for the stack just past the end of the program and data memory, and it does get overwritten when you F11 / redownload.

    Also, protoboards come with a surface mount 24LC512 pre-installed. And any platform that has an 8-pin DIP socket for the EEPROM can easily be refitted with a 24LC512 (digikey has 'em, they're under $2).
  • hinvhinv Posts: 1,255
    edited 2010-02-16 14:16
    is there any larger compatible parts out yet?
  • Don MDon M Posts: 1,654
    edited 2010-02-16 15:05
    24lc1025
  • PavelPavel Posts: 43
    edited 2010-02-17 00:53
    24LC512 is pin by pin compatible and requires no changes in the wiring. 24LC1025 will work as well but make sure to tie the A2 pin high, otherwise the chip does not work.
Sign In or Register to comment.