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AT25DF021 Folha de dados(PDF) 16 Page - ATMEL Corporation |
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AT25DF021 Folha de dados(HTML) 16 Page - ATMEL Corporation |
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16 / 41 page ![]() 16 3677D–DFLASH–04/09 AT25DF021 Essentially, if the SPRL bit of the Status Register is in the logical “0” state (Sector Protection Registers are not locked), then writing a 00h to the first byte of the Status Register will perform a Global Unprotect without changing the state of the SPRL bit. Similarly, writing a 7Fh to the first byte of the Status Register will perform a Global Protect and keep the SPRL bit in the logical “0” state. The SPRL bit can, of course, be changed to a logical “1” by writing an FFh if software-lock- ing or hardware-locking is desired along with the Global Protect. If the desire is to only change the SPRL bit without performing a Global Protect or Global Unpro- tect, then the system can simply write a 0Fh to the first byte of the Status Register to change the Table 9-2. Valid SPRL and Global Protect/Unprotect Conditions WP State Current SPRL Value New Write Status Register Byte 1 Data Protection Operation New SPRL Value Bit 7 6 5 4 3 2 1 0 00 0 x 0 0 0 0 x x 0 x 0 0 0 1 x x 0 x 1 1 1 0 x x 0 x 1 1 1 1 x x 1 x 0 0 0 0 x x 1 x 0 0 0 1 x x 1 x 1 1 1 0 x x 1 x 1 1 1 1 x x Global Unprotect – all Sector Protection Registers reset to 0 No change to current protection. No change to current protection. No change to current protection. Global Protect – all Sector Protection Registers set to 1 Global Unprotect – all Sector Protection Registers reset to 0 No change to current protection. No change to current protection. No change to current protection. Global Protect – all Sector Protection Registers set to 1 0 0 0 0 0 1 1 1 1 1 0 1 x x x x x x x x No change to the current protection level. All sectors currently protected will remain protected and all sectors currently unprotected will remain unprotected. The Sector Protection Registers are hard-locked and cannot be changed when the WP pin is LOW and the current state of SPRL is 1. Therefore, a Global Protect/Unprotect will not occur. In addition, the SPRL bit cannot be changed (the WP pin must be HIGH in order to change SPRL back to a 0). 10 0 x 0 0 0 0 x x 0 x 0 0 0 1 x x 0 x 1 1 1 0 x x 0 x 1 1 1 1 x x 1 x 0 0 0 0 x x 1 x 0 0 0 1 x x 1 x 1 1 1 0 x x 1 x 1 1 1 1 x x Global Unprotect – all Sector Protection Registers reset to 0 No change to current protection. No change to current protection. No change to current protection. Global Protect – all Sector Protection Registers set to 1 Global Unprotect – all Sector Protection Registers reset to 0 No change to current protection. No change to current protection. No change to current protection. Global Protect – all Sector Protection Registers set to 1 0 0 0 0 0 1 1 1 1 1 11 0 x 0 0 0 0 x x 0 x 0 0 0 1 x x 0 x 1 1 1 0 x x 0 x 1 1 1 1 x x 1 x 0 0 0 0 x x 1 x 0 0 0 1 x x 1 x 1 1 1 0 x x 1 x 1 1 1 1 x x No change to the current protection level. All sectors currently protected will remain protected, and all sectors currently unprotected will remain unprotected. The Sector Protection Registers are soft-locked and cannot be changed when the current state of SPRL is 1. Therefore, a Global Protect/Unprotect will not occur. However, the SPRL bit can be changed back to a 0 from a 1 since the WP pin is HIGH. To perform a Global Protect/Unprotect, the Write Status Register command must be issued again after the SPRL bit has been changed from a 1 to a 0. 0 0 0 0 0 1 1 1 1 1 |
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