mc9s08sh8mwjr Freescale Semiconductor, Inc, mc9s08sh8mwjr Datasheet - Page 45

• Manufacturer Part Number: mc9s08sh8mwjr
• Description: S08sh 5-volt 8-bit Microcontrollers With Sci, Spi, I2c, Adc And Analog Comparators
• Manufacturer: Freescale Semiconductor, Inc

0xFFAE
0xFFAF
0xFFB0 –
0xFFB7
0xFFB8 –
0xFFBB
0xFFBC
0xFFBD
0xFFBE
0xFFBF
Nonvolatile FLASH registers, shown in
include an 8-byte backdoor key, NVBACKKEY, which can be used to gain access to secure memory
resources. During reset events, the contents of NVPROT and NVOPT in the nonvolatile register area of the
FLASH memory are transferred into corresponding FPROT and FOPT working registers in the high-page
registers to control security and block protection options.
Provided the key enable (KEYEN) bit is 1, the 8-byte comparison key can be used to temporarily
disengage memory security. This key mechanism can be accessed only through user code running in secure
memory. (A security key cannot be entered directly through background debug commands.) This security
key can be disabled completely by programming the KEYEN bit to 0. If the security key is disabled, the
only way to disengage security is by mass erasing the FLASH if needed (normally through the background
debug interface) and verifying that FLASH is blank. To avoid returning to secure mode after the next reset,
program the security bits (SEC) to the unsecured state (1:0).
Freescale Semiconductor
Address
NVFTRIM
NVTRIM
NVBACKKEY
Reserved
Reserved for stor-
age of 250 kHz
ICGTRM value
NVPROT
Reserved for stor-
age of 243 kHz
ICGTRM value
NVOPT
Register Name
KEYEN
Bit 7
—
—
—
0
Table 4-4. Nonvolatile Register Summary
MC9S08SH32 Series Data Sheet, Rev. 2
FNORED
—
—
—
6
0
Table
PRELIMINARY
4-4, are located in the FLASH memory. These registers
—
—
—
5
0
0
8-Byte Comparison Key
FPS
—
—
—
4
0
0
TRIM
—
—
—
3
0
0
—
—
—
2
0
0
—
—
—
1
0
Chapter 4 Memory
SEC
FTRIM
FPDIS
Bit 0
—
—
—
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