SEC[0:1] bits setting in FSEC of S12XHY

[OliverTian]

Hi,
 In S12XHY, if application would like to secure the BDM, SEC[1:0] in FSEC (0x7F_FF0F) could be set to 00/01/11, as manual says. If code downloaded through CyclonePro, all the function could be as manual described. But if used 3rd party tools to program the code into flash and read out flash data through bootloader, all the codes are same as design, but D-Flash operation was blocked when SEC[1:0] = 00/11. 

There is a note for SEC[1:0] and 01 is the 'preferred SEC state to set MCU to secured state'.

Could you explain the difference for SEC[1:0] to be set as 00/11 and 01?

Thanks

Oliver

[iggi]

Oliver,

Additionally, pay attention on cumulative writes to Flash memory. A flash memory location has to be erased before any write. Find more details in this document https://community.nxp.com/docs/DOC-93803 

Also, there seems to be a bug on S12XHY and S12XS demo boards when using backdoor access key and security feature, but the actual problem was that after setting SEC bit to secure state, the MCU didn't get secured after reset.

Regards,

iggi

[iggi]

Hi Oliver,

interesting what you found. We use pemicro programmers as well and didn't know that there can be a problem with 3rd party tools.

Also i am not sure why the '01' is preferred SEC state.

I will investigate this. We'll see if anybody else have some feedback about this subject.

Regards,

iggi