Non-Secure Write Protection - STMicroelectronics SPC572L series Reference Manual

Flash Memory Programming and Configuration
Table 326. Sample low and mid address space flash block bit mapping(Continued)
Start Address End Address
0x0040_0000 0x0040_3FFF
1. There are multiple sets of LOCKn registers, i.e., the flash module's LOCK0–-3 registers and PASS module's
PASS_LOCK0–3_PG0–3, but all use the same mapping of register bits to flash blocks. The same mapping applies the the
flash module's SEL0–3 registers.
2. The DCF record DATA bit refers to the DATA[31:0] field contained in DCF records created during OEM configuration
activities. The DCF records related to flash blocks are used to implement password-secured write protection, password-
secured read protection, tamper detection, and debug port enable/disable as a permanent part of the device configuration.
3. The Read Lock group pertains to protecting code and data blocks from being read by debuggers. This type of protection is
implemented using DCF records and the PASS_LOCK3_PG0–3 registers.
4. The Boot Assist Flash (BAF) is one time programmable and the majority of it is programmed in the factory. The BAF
handles the initial start up of the device.
5. This block is searched to determine the boot location (if it contains the boot header).
6. One time programmable.
Referring to
selects the following blocks for erase:
Start Address End Address
0x00FC_C000 0x00FC_FFFF
Note: The mappings of SELn register bits to flash blocks vary with different microcontrollers. See
the flash memory section in the Device Configuration chapter of this reference manual for
the mappings specific to the SPC572Lx microcontroller.
31.2

Non-secure write protection

Non-secure write protection refers to the chip's ability to lock individual flash blocks against
programming and erase operations. This level of protection is intended to provide protection
against accidental changes to code and data. Although similar in function, this is not
associated with the built-in register protection (REG_PROT) feature included with many of
the chip's modules. The non-secure write protection feature detailed here applies only to
embedded flash memory.
Implementing non-secure write protection is almost identical to selecting specific flash
blocks for an erase operation—the only difference is the register used. To provide non-
658/2058
LOCKn
Size
(1)
(KB)
Register
16 0 LOCK0
Example 12. Selecting blocks for erase
Table 326, writing the value 0x0030_0000 to the SEL0 register
Size LOCKn
(KB) Register
16 1 LOCK0
DocID027809 Rev 4
LOCKn
LOCKn DCF
Register Field Record
Bit DATA
(2)
Bit
TSLOCK 31
LOCKn
LOCKn DCF
Register Field Record
Bit DATA
Bit
LOWLOCK[4] 20
RM0400
Read
Lock Bloc
Description
group k No.
(3)
0 32 UTEST
(Figure 286)
Read
Bloc
Lock Description
k No.
group
1 4 Code Flash
(6)
4