mc9s12xs128 Freescale Semiconductor, Inc, mc9s12xs128 Datasheet - Page 231

• Manufacturer Part Number: mc9s12xs128
• Description: Hcs12 Microcontrollers 16-bit Automotive Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

SEC[1:0] = ‘10’. All other combinations put the device in a secured mode. The recommended value to put
the device in secured state is the inverse of the unsecured state, i.e. SEC[1:0] = ‘01’.
7.1.4
By securing the device, unauthorized access to the EEPROM and Flash memory contents can be prevented.
However, it must be understood that the security of the EEPROM and Flash memory contents also depends
on the design of the application program. For example, if the application has the capability of downloading
code through a serial port and then executing that code (e.g. an application containing bootloader code),
then this capability could potentially be used to read the EEPROM and Flash memory contents even when
the microcontroller is in the secure state. In this example, the security of the application could be enhanced
by requiring a challenge/response authentication before any code can be downloaded.
Secured operation has the following effects on the microcontroller:
Freescale Semiconductor
Operation of the Secured Microcontroller
Please refer to the Flash block guide for actual security configuration (in
section “Flash Module Security”).
SEC[1:0]
S12XS Family Reference Manual, Rev. 1.10
00
01
10
11
Table 7-4. Security Bits
NOTE
Security State
0 (unsecured)
1 (secured)
1 (secured)
1 (secured)
Security (S12XS9SECV2)
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