S912XEG128J2VAL
| Model | S912XEG128J2VAL |
| Description | IC,MICROCONTROLLER,16-BIT,CPU12 CPU,CMOS,QFP,112PIN,PLASTIC |
| PDF file | Total 1327 pages (File size: 7M) |
| Chip Manufacturer | ROCHESTER |
Chapter 27 512 KByte Flash Module (S12XFTM512K3V1)
27.3.2.2
Flash Security Register (FSEC)
Because of an order from the United States International Trade Commission, BGA-packaged product lines and part numbers indicated here currently are not
available from Freescale for import or sale in the United States prior to September 2010: S12XE products in 208 MAPBGA packages
The FSEC register holds all bits associated with the security of the MCU and Flash module.
Offset Module Base + 0x0001
7
6
5
4
3
2
1
0
R
W
Reset
F
KEYEN[1:0]
RNV[5:2]
SEC[1:0]
F
F
F
F
F
F
F
= Unimplemented or Reserved
Figure 27-6. Flash Security Register (FSEC)
All bits in the FSEC register are readable but not writable.
During the reset sequence, the FSEC register is loaded with the contents of the Flash security byte in the
Flash configuration field at global address 0x7F_FF0F located in P-Flash memory (see
Table 27-3)
as
indicated by reset condition F in
Figure 27-6.
If a double bit fault is detected while reading the P-Flash
phrase containing the Flash security byte during the reset sequence, all bits in the FSEC register will be
set to leave the Flash module in a secured state with backdoor key access disabled.
Table 27-10. FSEC Field Descriptions
Field
Description
7–6
Backdoor Key Security Enable Bits
— The KEYEN[1:0] bits define the enabling of backdoor key access to the
KEYEN[1:0] Flash module as shown in
Table 27-11.
5–2
RNV[5:2}
1–0
SEC[1:0]
Reserved Nonvolatile Bits
— The RNV bits should remain in the erased state for future enhancements.
Flash Security Bits
— The SEC[1:0] bits define the security state of the MCU as shown in
Table 27-12.
If the
Flash module is unsecured using backdoor key access, the SEC bits are forced to 10.
Table 27-11. Flash KEYEN States
KEYEN[1:0]
00
01
10
Status of Backdoor Key Access
DISABLED
DISABLED
(1)
ENABLED
11
DISABLED
1. Preferred KEYEN state to disable backdoor key access.
Table 27-12. Flash Security States
SEC[1:0]
00
01
10
11
Status of Security
SECURED
SECURED
(1)
UNSECURED
SECURED
MC9S12XE-Family Reference Manual , Rev. 1.19
Freescale Semiconductor
1029
