S71WS256NC0BAWE32 SPANSION [SPANSION], S71WS256NC0BAWE32 Datasheet - Page 68

• Manufacturer Part Number: S71WS256NC0BAWE32
• Description: Stacked Multi-Chip Product (MCP)
• Manufacturer: SPANSION [SPANSION]

13.2
13.3
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Customer Secured Silicon Sector
Secured Silicon Sector Entry/Exit Command Sequences
The Customer Secured Silicon Sector is typically shipped unprotected (DQ6 set to “0”), allowing
customers to utilize that sector in any manner they choose. If the security feature is not required,
the Customer Secured Silicon Sector can be treated as an additional Flash memory space.
Please note the following:
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 re-
gion until the system issues the four-cycle Exit Secured Silicon Sector command sequence.
See Command Definition Table [Secured Silicon Sector Command Table, Appendix
Table 15.1
The Secured Silicon Sector Entry Command allows the following commands to be executed
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.
The following are C functions and source code examples of using the Secured Silicon Sector
Entry, Program, and exit commands. Refer to the Spansion Low Level Driver User’s Guide
(available soon on www.amd.com and www.fujitsu.com) for general information on Spansion
Flash memory software development guidelines.
Software Functions and Sample Code
Once the Customer Secured Silicon Sector area is protected, the Customer Indicator Bit is
permanently set to “1.”
The Customer Secured Silicon Sector can be read any number of times, but can be pro-
grammed and locked only once. The Customer Secured Silicon Sector lock must be used with
caution as once locked, there is no procedure available for unlocking the Customer Secured
Silicon Sector area and none of the bits in the Customer Secured Silicon Sector memory space
can be modified in any way.
The accelerated programming (ACC) and unlock bypass functions are not available when pro-
gramming the Customer Secured Silicon Sector, but reading in Banks 1 through 15 is avail-
able.
Once the Customer 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 mem-
ory array at sector 0.
Read customer and factory Secured Silicon areas
Program the customer Secured Silicon Sector
for address and data requirements for both command sequences.
A d v a n c e
S71WS-Nx0 Based MCPs
I n f o r m a t i o n
S71WS-N_01_A4 September 15, 2005