MC9S12XF512 Datasheet, PDF (135/1300 Pages) Freescale Semiconductor, Inc – S12X Microcontrollers

Chapter 5
Security (S12XFSECV2)
Revision History
Version
Number
01.00
02.00
02.01
Revision
Date
26 Sep
2003
27 Aug
2004
21 Feb
2007
Effective
Date
26 Sep
2003
08 Sep
2004
21 Feb
2007
Author
Initial Release
Description of Changes
reviewed and updated for S12XD architecture
added S12XE, S12XF and S12XS architectures
5.1 Introduction
This specification describes the function of the security mechanism in the S12XF chip family (SEC).
5.1.1 Features
The user must be reminded that part of the security must lie with the application code. An extreme example
would be application code that dumps the contents of the internal memory. This would defeat the purpose
of security. At the same time, the user may also wish to put a backdoor in the application program. An
example of this is the user downloads a security key through the SCI, which allows access to a
programming routine that updates parameters stored in another section of the Flash memory.
The security features of the S12XDF chip family (in secure mode) are:
• Protect the content of non-volatile memories (Flash, EEPROM)
• Execution of NVM commands is restricted
• Disable access to internal memory via background debug module (BDM)
• Disable access to internal Flash/EEPROM in expanded modes
• Disable debugging features for the CPU and XGATE
Table 5-1 gives an overview over availability of security relevant features in unsecure and secure modes.
MC9S12XF - Family Reference Manual, Rev.1.18
Freescale Semiconductor
137