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Implementation of Dynamic Sector Protection scheme (DYB) in FL-S SPI NOR Flash - KBA232759

ArunKumarChoul
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Implementation of Dynamic Sector Protection scheme (DYB) in FL-S SPI NOR Flash - KBA232759

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Dynamic Protection Bits are volatile and unique for each sector and can be individually modified. By issuing the DYB Write command, a DYB is cleared to ‘0’ or set to ‘1’, thus placing each sector in the protected or unprotected state respectively. This feature allows software to easily protect sectors against inadvertent changes, yet does not prevent the easy removal of protection when changes are needed. The DYBs can be set or cleared as often as needed as they are volatile bits.

Every sector in the main flash array has an associated volatile dynamic protection bit (DYB). When the bit is ‘0’, the sector is protected from program and erase operations. When the bit is ‘1’, the sector is in unprotected state. This bit is written to and read from the flash in the form of a one-byte data, which is held in DYB Access Register (DYBAR).

If the DYBAR value associated with a particular sector is 0x00, the particular sector is protected from program and erase operations by DYB. If the DYBAR value associated with a particular sector is 0xFF, the particular sector is not protected from program and erase operations by DYB.

Table 1. DYB Access Register (DYBAR)

ArunKumarChoul_0-1618486320399.png


The DYBAR value can be read using the DYB Read (0xE0) command. The DYBAR value can be written using the DYB Write (0xE1) command.

Please note that the protection scheme only protects the sector against program and erase; read operations are not impacted.

The dynamic sector protection scheme can be executed in the following way:

  1. Drive CS# LOW.
  2. Send the WREN command.
  3. Drive CS# HIGH.
  4. Drive CS# LOW.
  5. Send the DYBWR command.
  6. Send the 32-bit address selecting location zero within the desired sector.
  7. Send the data byte (00h for protecting, FFh for unprotecting).
  8. Drive CS# HIGH.

DYBAR is a volatile register; it is reset to the default value after a power cycle or reset.

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‎Apr 15, 2021 04:36 AM
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