MC9S08SH32 Datasheet, PDF (56/328 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 4 Memory
Table 4-9. Security States¹
SEC01:SEC00
Description
0:0
secure
0:1
secure
1:0
unsecured
1:1
secure
1 _{SEC01:SEC00 changes to 1:0 after successful backdoor}
key entry or a successful blank check of FLASH.
4.7.3 FLASH Configuration Register (FCNFG)
7
6
5
4
3
2
1
0
R
0
0
0
0
0
0
0
KEYACC
W
Reset
0
0
0
0
0
0
0
0
= Unimplemented or Reserved
Figure 4-7. FLASH Configuration Register (FCNFG)
Table 4-10. FCNFG Register Field Descriptions
Field
Description
5
KEYACC
Enable Writing of Access Key — This bit enables writing of the backdoor comparison key. For more detailed
information about the backdoor key mechanism, refer to Section 4.6, “Security.”
0 Writes to 0xFFB0–0xFFB7 are interpreted as the start of a FLASH programming or erase command.
1 Writes to NVBACKKEY (0xFFB0–0xFFB7) are interpreted as comparison key writes.
4.7.4 FLASH Protection Register (FPROT and NVPROT)
During reset, the contents of the nonvolatile location NVPROT are copied from FLASH into FPROT. This
register can be read at any time. If FPDIS = 0, protection can be increased (that is, a smaller value of FPS
can be written). If FPDIS = 1, writes do not change protection.
7
R
W
Reset
6
5
4
3
2
1
FPS⁽¹⁾
This register is loaded from nonvolatile location NVPROT during reset.
0
FPDIS⁽¹⁾
1 _{Background commands can be used to change the contents of these bits in FPROT.}
Figure 4-8. FLASH Protection Register (FPROT)
MC9S08SH32 Series Data Sheet, Rev. 2
56
Freescale Semiconductor
PRELIMINARY