Document Number: 002-00886 Rev. *B
S29GL01GP
S29GL512P
S29GL256P
S29GL128P
10.2
Customer Lockable Secured Silicon Sector
The Customer Lockable Secured Silicon Sector is always shipped unprotected (DQ7 set to “0”), allowing customers to utilize that
sector in any manner they choose. If the security feature is not required, the Secured Silicon Sector can be treated as an additional
Flash memory space.
Please note the following:
Once the Secured Silicon Sector area is protected, the Secured Silicon Sector Indicator Bit is permanently set to “0.”
The Secured Silicon Sector can be read any number of times, but can be programmed and locked only once. The Secured
Silicon Sector lock must be used with caution as once locked, there is no procedure available for unlocking the Secured Silicon
Sector area and none of the bits in the Secured Silicon Sector memory space can be modified in any way.
The accelerated programming (ACC) and unlock bypass functions are not available when the Secured Silicon Sector is enabled.
Once the Secured Silicon Sector is locked and verified, the system must write the Exit Secured Silicon Sector Region command
sequence which return the device to the memory array at sector 0.
10.3
Secured Silicon Sector Entry/Exit Command Sequences
The system can access the Secured Silicon Sector region by issuing the three-cycle Enter Secured Silicon Sector command
sequence. The device continues to access the Secured Silicon Sector region until the system issues the four-cycle Exit Secured
Silicon Sector command sequence.
See
[Secured Silicon Sector Command Table, Appendix
through
for address and data requirements for both command sequences.
The Secured Silicon Sector Entry Command allows the following commands to be executed
Read customer and factory Secured Silicon areas
Program the customer Secured Silicon Sector
After the system has written the Enter Secured Silicon Sector command sequence, it may read the Secured Silicon Sector by using
the addresses normally occupied by sector SA0 within the memory array. This mode of operation continues until the system issues
the Exit Secured Silicon Sector command sequence, or until power is removed from the device.
Software Functions and Sample Code
The following are C functions and source code examples of using the Secured Silicon Sector Entry, Program, and exit commands.
Refer to the
Cypress Low Level Driver User’s Guide
www.cypress.com
) for general information on Cypress Flash
memory software development guidelines.
Note
Base = Base Address.
/* Example: SecSi Sector Entry Command */
*( (UINT16 *)bas 0x555 ) = 0x00AA; /* write unlock cycle 1 */
*( (UINT16 *)bas 0x2AA ) = 0x0055; /* write unlock cycle 2 */
*( (UINT16 *)bas 0x555 ) = 0x0088; /* write Secsi Sector Entry Cmd */
Secured Silicon Sector Entry
(LLD Function = lld_SecSiSectorEntryCmd)
Cycle
Operation
Byte Address
Word Address
Data
Unlock Cycle 1
Write
Base + AAAh
Base + 555h
00AAh
Unlock Cycle 2
Write
Base + 555h
Base + 2AAh
0055h
Entry Cycle
Write
Base + AAAh
Base + 555h
0088h
