mc9s08jm16 Freescale Semiconductor, Inc, mc9s08jm16 Datasheet - Page 57

• Manufacturer Part Number: mc9s08jm16
• Description: S08jm 8-bit Usb Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

1
SEC01:SEC00 changes to 1:0 after successful backdoor key entry or a successful blank check of flash.
4.7.3
Bits 7 through 5 may be read or written at any time. Bits 4 through 0 always read 0 and cannot be written.
4.7.4
During reset, the contents of the nonvolatile location NVPROT are copied from flash into FPROT. Bits 0,
1, and 2 are not used and each always reads as 0. This register may be read at any time, but user program
writes have no meaning or effect. Background debug commands can write to FPROT.
Freescale Semiconductor
Background commands can be used to change the contents of these bits in FPROT.
KEYACC
Reset
Reset
Field
5
W
W
R
R
FPS7
Flash Configuration Register (FCNFG)
Flash Protection Register (FPROT and NVPROT)
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
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.
0
0
7
7
1
= Unimplemented or Reserved
FPS6
0
0
6
6
1
This register is loaded from nonvolatile location NVPROT during reset.
Figure 4-7. Flash Configuration Register (FCNFG)
SEC01:SEC00
Table 4-10. FCNFG Register Field Descriptions
Figure 4-8. Flash Protection Register (FPROT)
0:0
0:1
1:0
1:1
KEYACC
MC9S08JM16 Series Data Sheet, Rev. 2
FPS5
0
5
5
1
Table 4-9. Security States
FPS4
0
0
4
4
1
Description
Section 4.6,
FPS3
3
0
0
3
1
Description
Unsecured
Secure
Secure
Secure
“Security.”
FPS2
0
0
2
2
1
FPS1
0
0
1
1
1
Chapter 4 Memory
FPDIS
0
0
0
0
1
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