MC9S12XD256MAL Datasheet, PDF (1230/1348 Pages) Freescale Semiconductor, Inc – Freescale’s Scalable Controller Area Network

Chapter 30 Security (S12X9SECV2)
Table 30-1. Features Availability in Unsecure and Secure Modes
Unsecure Mode
Secure Mode
NS SS NX ES EX ST NS SS NX ES EX ST
Flash Array Access
✔ ✔ ✔¹ ✔¹ ✔¹ ✔¹ ✔ ✔ — — — —
EEPROM Array Access ✔ ✔ ✔ ✔ ✔ ✔ ✔ ✔ — — — —
NVM Commands
✔² ✔ ✔² ✔² ✔² ✔ ✔² ✔² ✔² ✔² ✔² ✔²
BDM
✔ ✔ ✔ ✔ ✔ ✔ — ✔³ — — — —
DBG Module Trace
✔ ✔ ✔ ✔ ✔ ✔——————
XGATE Debugging
✔ ✔ ✔ ✔ ✔ ✔——————
External Bus Interface — — ✔ ✔ ✔ ✔ — — ✔ ✔ ✔ ✔
Internal status visible
multiplexed on
external bus
———✔ ✔————✔ ✔—
Internal accesses visible — — — — — ✔ — — — — — ✔
on external bus
1 _{Availability of Flash arrays in the memory map depends on ROMCTL/EROMCTL pins and/or the state of}
the ROMON/EROMON bits in the MMCCTL1 register. Please refer to the S12X_MMC block guide for
detailed information.
2 _{Restricted NVM command set only. Please refer to the FTX/EETX block guides for detailed information.}
3 _{BDM hardware commands restricted to peripheral registers only.}
30.1.2 Modes of Operation
30.1.3 Securing the Microcontroller
Once the user has programmed the Flash and EEPROM, the chip can be secured by programming the
security bits located in the options/security byte in the Flash memory array. These non-volatile bits will
keep the device secured through reset and power-down.
The options/security byte is located at address 0xFF0F (= global address 0x7F_FF0F) in the Flash memory
array. This byte can be erased and programmed like any other Flash location. Two bits of this byte are used
for security (SEC[1:0]). On devices which have a memory page window, the Flash options/security byte
is also available at address 0xBF0F by selecting page 0x3F with the PPAGE register. The contents of this
byte are copied into the Flash security register (FSEC) during a reset sequence.
7
6
0xFF0F KEYEN1 KEYEN0
5
NV5
4
NV4
3
NV3
2
NV2
Figure 30-1. Flash Options/Security Byte
1
SEC1
0
SEC0
1232
MC9S12XDP512 Data Sheet, Rev. 2.21
Freescale Semiconductor