ST SPC560P34 - Table 451. Censorship Configuration and Truth Table

RM0046 Boot Assist Module (BAM)
Doc ID 16912 Rev 5 833/936
Table 451 shows all the possible modes of censorship. The red shaded areas are to be
avoided as these show the configuration for a device that is permanently locked out. If you
wish to enable censorship with a private password there is only one valid configuration — to
modify the CW field in both NVSCI0,1 registers so they match but do not equal 0x55AA.
This will allow you to enter the private password in both serial and flash boot modes.
The flow charts in Figure 493 and Figure 494 provide a way to quickly check what will
happen with different configurations of the NVSCI0,1 registers as well as detailing the
correct way to enter the serial password. In the password examples, assume the 64-bit
Table 451. Censorship configuration and truth table
Boot configuration
Serial
censorship
control word
(NVSCIn[SC])
Censorship
control word
(NVSCIn[CW])
Internal
flash
memory
state
Nexus
state
Serial
password
JTAG
password
FAB
pin
state
Control options
0 (flash
memor
y boot)
Uncensored
0xXXXX AND
NVSCI0 ==
NVSCI1
0x55AA AND
NVSCI0 ==
NVSCI1
Enabled Enabled
N/A
Private flash
memory password
and censored
0x55AA AND
NVSCI0 ==
NVSCI1
!0x55AA AND
NVSCI0 ==
NVSCI1
Enabled
Enabled
with
password
NVPWD1,0
(SSCM
reads flash
memory
(1)
)
Censored with no
password access
(lockout)
!0x55AA !0X55AA
Enabled Disabled N/A
OR
NVSCI0 != NVSCI1
1
(serial
boot)
Private flash
memory password
and uncensored
0x55AA AND
NVSCI0 == NVSCI1
Enabled Enabled
NVPWD0,1
(BAM reads
flash
memory
(1)
)
Private flash
memory password
and censored
0x55AA AND
NVSCI0 ==
NVSCI1
!0x55AA AND
NVSCI0 ==
NVSCI1
Enabled Disabled
NVPWD1,0
(SSCM
reads flash
memory
(1)
)
Public password
and uncensored
!0x55AA AND
NVSCI0 !=
NVSCI1
0X55AA AND
NVSCI0 !=
NVSCI1
Enabled Enabled
Public
(0xFEED_F
ACE_CAFE
_BEEF)
Public password
and censored
(lockout)
!0x55AA
Disabled Disabled
Public
(0xFEED_F
ACE_CAFE
_BEEF)
OR NVSCI0 != NVSCI1
= Microcontroller permanently locked out
= Not applicable
1. When the SSCM reads the passwords from flash memory, the NVPWD0 and NVPWD1 password order is swapped, so you
have to submit the 64-bit password as {NVPWD1, NVPWD0}.