Datasheet

Chapter 4 Memory Map and Register Definition
MC9S08QD4 Series MCU Data Sheet, Rev. 6
36 Freescale Semiconductor
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).
The ICS factory-trimmed value will be stored in 0xFFAE (bit-0) and 0xFFAF. Development tools, such as
programmers can trim the ICS and the internal temperature sensor (via the ADC) and store the values in
0xFFAD–0xFFAF.
4.4 RAM
The MC9S08QD4 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.
The RAM retains data when the MCU is in low-power wait, stop2, or stop3 mode. At power-on or after
wakeup from stop1, the contents of RAM are uninitialized. RAM data is unaffected by any reset provided
that the supply voltage does not drop below the minimum value for RAM retention (V
RAM
).
Table 4-4. Nonvolatile Register Summary
AddressRegister NameBit 7654321Bit 0
0xFFAA –
0xFFAC
Reserved
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0xFFAD Reserved for
ADCRL of AD26
value during ICS
trim
ADR7 ADR6 ADR5 ADR4 ADR3 ADR2 ADR1 ADR0
0xFFAE Reserved for
ADCRH of AD26
value during ICS
trim and ICS Trim
value “FTRIM”
ADR9 ADR8
— — — — —FTRIM
0xFFAF Reserved for
ICS Trim value
“TRIM”
TRIM
0xFFB0 –
0xFFB7
NVBACKKEY
8-Byte Comparison Key
0xFFB8 –
0xFFBC
Reserved
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
0xFFBD NVPROT FPS FPDIS
0xFFBE Unused
— — — — — — — —
0xFFBF NVOPT KEYEN FNORED
0 0 0 0 SEC01 SEC00