censorship can be enabled by modifying the content of shadow flash block. The memory address of the censorship control word is 0x00FF_FDE0. By default, the censorship control word is programmed to be 0x55AA_55AA. This results in a device that is not censored and uses a flash-based password for serial-boot mode. The password is at address 0xFF_FDD8. Take a look at reference manual, Table 8-2 on page 245 (8-3): http://www.freescale.com/files/32bit/doc/ref_manual/MPC5668xRM.pdf
This table shows the state of flash, nexus and serial password for all modes. Important warning here: if you erase the flash and if you don’t restore the data or if you restore wrong data then the chip can be locked forever after power-down or reset.
How to change the shadow flash – it depends on your tools. For example, you can use this procedure: 1. Download whole shadow block into s-record file. 2. Modify the s-record file accordingly. 3. Burn new s-record file into shadow flash.
