Datasheet

Table Of Contents
Operating Modes
MC9S12DP256 — Revision 1.1
Operating Modes
The user can select any of the three combinations to secure the
microcontroller.
CAUTION:
Check the Flash Specification for more details on the security
configuration.
Operation of the
Secured
Microcontroller
Normal Single
Chip Mode
This will be the most common usage of the secured part. Everything will
appear the same as if the part was not secured with the exception of
BDM operation. The BDM operation will be blocked.
Executing from
External Memory
The user may wish to execute from external space with a secured
microcontroller. This is accomplished by resetting directly into expanded
mode. The internal FLASH and EEPROM will be disabled. BDM
operations will be blocked.
Unsecuring the
Microcontroller
In order to unsecure the microcontroller, the internal FLASH and
EEPROM must be erased. This can be done through an external
program in expanded mode.
Once the user has erased the FLASH and EEPROM, the part can be
reset into special single chip mode. This invokes a program that verifies
the erasure of the internal FLASH and EEPROM. Once this program
completes, the user can erase and program the FLASH security bits to
Table 15 : Security Bits
sec1 sec0 secreq
0 0 1 (secured)
0 1 1 (secured)
1 0 0 (unsecured)
1 1 1 (secured)
Freescale Semiconductor, I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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