SRI512 Memory mapping
Doc ID 13263 Rev 5 19/47
4.4 System area
This area is used to modify the settings of the SRI512. It contains 3 registers:
OTP_Lock_Reg, Fixed Chip_ID and ST Reserved. See Figure 18 for a map of this area.
A Write_block command in this area will not erase the previous contents. Selected bits can
thus be set from 1 to 0. All bits previously at 0 remain unchanged. Once all the 32 bits of a
block are at 0, the block is empty and cannot be updated any more.
Figure 18. System area
4.4.1 OTP_Lock_Reg
The 16 bits, b31 to b16, of the System area (block address 255) are used as
OTP_Lock_Reg bits in the SRI512. They control the write access to the 16 blocks 0 to 15 as
follows:
● When b16 is at 0, block 0 is write-protected
● When b17 is at 0, block 1 is write-protected
● When b18 is at 0, block 2 is write-protected
● When b19 is at 0, block 3 is write-protected
● When b20 is at 0, block 4 is write-protected
● When b21 is at 0, block 5 is write-protected
● When b22 is at 0, block 6 is write-protected
● When b23 is at 0, block 7 is write-protected
● When b24 is at 0, block 8 is write-protected
● When b25 is at 0, block 9 is write-protected
● When b26 is at 0, block 10 is write-protected
● When b27 is at 0, block 11 is write-protected
● When b28 is at 0, block 12 is write-protected
● When b29 is at 0, block 13 is write-protected
● When b30 is at 0, block 14 is write-protected
● When b31 is at 0, block 15 is write-protected.
The OTP_Lock_Reg bits cannot be erased. Once write-protected, the blocks behave like
ROM blocks and cannot be unprotected. After any modification of the OTP_Lock_Reg bits, it
is necessary to send a Select command with a valid Chip_ID to the SRI512 in order to load
the block write protection into the logic.
Block
Address
255
MSb 32-bit Block LSb
Description
OTP
OTP_Lock_Reg ST Reserved
Fixed Chip_ID
(Option)
ai12374b
0
b31 b16 b15 b14 b8 b7 b0
