Page-mode EEPROM - may I write a singe byte?

Discussion in 'Embedded Systems and Microcontrollers' started by atferrari, Jun 19, 2009.

  1. atferrari

    Thread Starter AAC Fanatic!

    Jan 6, 2004
    I am currently trying to use this page-mode EEPROM

    Accoding to what I understood, every time a "write" order is issued, an internal Write Cycle executes the writing of a full page (128 bytes) with the contents of an internal buffer.

    My questions:

    a) While not explicitly said, it seems that I could write just one byte if desired. Am I wrong? If not, how should I do that?

    b) During the byte load cycle, let's say that I pass a value of H'33' for the first ten bytes in the buffer. Will the rest of the buffer acquire a value of 0 or H'FF'?
    After completing the writing, that page in the EEPROM would have the first ten bytes = H'33'. And the rest of that page?

    c) Or it is that I must compulsory give the 128 values, even if they are 0s for the write cycle to proceed?

    The flow diagram is ambiguous (at least for me) because it seems that I could write some of the bytes in the target page.

    Anyone with experience on this modality?
  2. n9352527

    AAC Fanatic!

    Oct 14, 2005
    a) You can load a single byte to the page buffer, but the rest of the page buffer will be loaded with the default value of 0xFF. The subsequent erase (erase before write is always performed) and write sequences will write the one byte and the rest of 127 bytes of 0xFF to the EEPROM memory.

    If you want to change just one single byte, then you have to read the whole page to an external buffer, change the single byte, then write the content of the buffer back to the EEPROM's page buffer and commence the write sequence.

    b) See above. In short 0xFF.

    c) No.
  3. atferrari

    Thread Starter AAC Fanatic!

    Jan 6, 2004
    Crystal clear now. Gracias!!