EEPROM pages


Joined Feb 24, 2006
It is hard to answer your question without reference to a specific part. As you know in a RAM you can typically read and write individual words(bytes). In an EEPROM or Flash memory you typically want to write in blocks because you must erase an entire block in order to write a single word(byte). Blocks can be any convenient size; they are not restricted to 256 bytes. Since read operations are more frequent than write operations this is usually not a problem.

The usual strategy to change a single byte is:

  1. Read an entire block(page) of EEPROM into RAM
  2. Erase the entire block(page)
  3. Write the data from RAM back to the EEPROM with a change to the desired word(byte)
  4. Turn on Write Enable
  5. Send the Write Command
  6. Wait for the write operation to complete
Depending on the actual chip the, order of operations may be slightly different or there may be other steps that are required.