S70FS01GS datasheet(44/141 Pages) CYPRESS

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S70FS01GS

Document Number: 002-03833 Rev. *C

Page 44 of 141

7.5

OTP Address Space

Each FS-S Family memory device has a 1024 byte One Time Program (OTP) address space that is separate from the main Flash

array. The OTP area is divided into 32, individually lockable, 32 byte aligned and length regions.

In the 32 byte region starting at address zero:



The 16 lowest address bytes are programmed by Cypress with a 128 bit random number. Only Cypress is able to program

zeros in these bytes. Programming ones in these byte locations is ignored and does not affect the value programmed by

Cypress. Attempting to program any zero in these byte locations will fail and set P_ERR.



The next 4 higher address bytes (OTP Lock Bytes) are used to provide one bit per OTP region to permanently protect each

region from programming. The bytes are erased when shipped from Cypress. After an OTP region is programmed, it can

be locked to prevent further programming, by programming the related protection bit in the OTP Lock Bytes.



The next higher 12 bytes of the lowest address region are Reserved for Future Use (RFU). The bits in these RFU bytes

may be programmed by the host system but it must be understood that a future device may use those bits for protection of

a larger OTP space. The bytes are erased when shipped from Cypress.

The remaining regions are erased when shipped from Cypress, and are available for programming of additional permanent data.

Refer to Figure 7.1, OTP Address Space on page 44 for a pictorial representation of the OTP memory space.

The OTP memory space is intended for increased system security. OTP values, such as the random number programmed by

Cypress, can be used to “mate” a flash component with the system CPU/ASIC to prevent device substitution.

The configuration register FREEZE (CR1V[0]) bit protects the entire OTP memory space from programming when set to “1”. This

allows trusted boot code to control programming of OTP regions then set the FREEZE bit to prevent further OTP memory space

programming during the remainder of normal power-on system operation.

Figure 7.1

OTP Address Space

32 Byte OTP Region 31

32 Byte OTP Region 30

32 Byte OTP Region 29

32 Byte OTP Region 3

32 Byte OTP Region 2

32 Byte OTP Region 1

32 Byte OTP Region 0

16 Byte Random Number

Lock Bits 31 to 0

Reserved

Region 0 Expanded View

When programmed to 0,

each lock bit protects its

related 32 byte OTP region

from any further program-

...

Byte 0h

Byte 10h

Byte 1Fh

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