Datasheet

Chapter 4 Memory
MC9S08LC60 Series Data Sheet: Technical Data, Rev. 4
Freescale Semiconductor 47
Nonvolatile FLASH registers, shown in Table 4-4, are located in the FLASH memory. These registers
include an 8-byte backdoor key which optionally 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 (SEC01:SEC00) to the unsecured state (1:0).
4.3 RAM
The MC9S08LC60 Series includes static RAM. The locations in RAM below 0x0100 can be accessed
using the more efficient direct addressing mode, and any single bit in this area can be accessed with the bit
manipulation instructions (BCLR, BSET, BRCLR, and BRSET). Locating the most frequently accessed
program variables in this area of RAM is preferred.
0x185D–
0x1861
Reserved
— — — — — — — —
0x1862 LCDCLKS SOURCE DIV16 CLKADJ5 CLKADJ4 CLKADJ3 CLKADJ2 CLKADJ1 CLKADJ0
0x1863 LCDSUPPLY LCDCPEN LCDCPMS CPCADJ1 CPCADJ0 HDRVBUF
BBYPASS VSUPPLY1 VSUPPLY0
0x1864 LCDBCTL
BLINK 0 0 0 BLKMODE BRATE2 BRATE1 BRATE0
0x1865 LCDCMD
LCDIF 0 0 0 LCDDRMS 0 LCDCLR BLANK
0x1866–
0x186F
Reserved
— — — — — — — —
Table 4-4. Nonvolatile Register Summary
Address
Register
Name
Bit 7 6 5 4 3 2 1 Bit 0
0xFFB0–
0xFFB7
NVBACKKEY
8-Byte Comparison Key
0xFFB8–
0xFFBC
Reserved
— — — — — — — —
0xFFBD NVPROT FPS7 FPS6 FPS5 FPS4 FPS3 FPS2 FPS1 FPDIS
0xFFBE NVICGTRM
1
1
Freescale Semiconductor provides a factory trim to set the FIRG to 243 kHz. If user code changes the value of the NVICGTRM
register, the factory trim value will be lost. User code should save the content of NVICGTRM before any mass erase operation.
NVTRIM
0xFFBF NVOPT KEYEN FNORED
0 0 0 0 SEC01 SEC00
Table 4-3. High-Page Register Summary (continued)
Address Register Name Bit 7 6 5 4 3 2 1 Bit 0