MC9S12G FREESCALE [Freescale Semiconductor, Inc], MC9S12G Datasheet - Page 325

• Manufacturer Part Number: MC9S12G
• Description: Ignores external trigger. Performs one conversion sequence and stops.
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

9.1.7
The microcontroller can be unsecured in special modes by erasing the entire EEPROM and Flash memory
contents.
When a secure microcontroller is reset into special single chip mode (SS), the BDM firmware verifies
whether the EEPROM and Flash memory are erased. If any EEPROM or Flash memory address is not
erased, only BDM hardware commands are enabled. BDM hardware commands can then be used to write
to the EEPROM and Flash registers to mass erase the EEPROM and all Flash memory blocks.
When next reset into special single chip mode, the BDM firmware will again verify whether all EEPROM
and Flash memory are erased, and this being the case, will enable all BDM commands, allowing the Flash
options/security byte to be programmed to the unsecured value. The security bits SEC[1:0] in the Flash
security register will indicate the unsecure state following the next reset.
Freescale Semiconductor
•
•
This document is valid for the S12G96 and the S12G128 device. All information related to other devices is preliminary.
The application software previously programmed into the microcontroller has been designed to
have the capability to erase and program the Flash options/security byte, or security is first disabled
using the backdoor key method, allowing BDM to be used to issue commands to erase and program
the Flash options/security byte.
The Flash sector containing the Flash options/security byte is not protected.
Complete Memory Erase (Special Modes)
MC9S12G Family Reference Manual, Rev.1.01
Security (S12XS9SECV2)
325