MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
Freescale Semiconductor 13-35
Table 13-17 shows the encoding of the BOOTCFG signals in conjunction with the value stored in the
Censorship word in the shadow row of internal flash memory. The table also shows: the name of the boot
mode; whether the internal flash memory is enabled or disabled; whether the Nexus port is enabled or
disabled; whether the password downloaded in serial boot mode is compared with a fixed public password
or compared to a user programmable flash password.
The FBIU returns a bus error if an access is attempted while flash access is disabled. Flash access is any
read, write or execute access.
13.4.2.6.3 FLASH_BIUAPR Modification
Censorship logic prevents modification of the access protection register (FLASH_BIUAPR) bit fields
associated with all masters except the core according to the logic presented in Table 13-18.
Table 13-17. Flash Access Disable Logic
BOOTCFG
1
[0:1]
1
BOOTCFG[0:1] bits are located in the SIU_RSR.
Censorship
Control
0x00FF_FDE0
(Upper Half)
Serial Boot
Control
0x00FF_FDE2
(Lower Half)
Boot Mode Name
Internal
Flash
State
Nexus
State
2
2
The Nexus port controller is held in reset when in censored mode.
Serial
Password
00 !0x55AA Don't care Internal—Censored Enabled Disabled Flash
0x55AA Internal—Public Enabled Enabled Public
01 Don't care 0x55AA Serial—Flash Password Enabled Disabled Flash
!0x55AA Serial—Public Password Disabled Enabled Public
10 !0x55AA Don't care External—No Arbitration—
Censored
Disabled Enabled Public
0x55AA External—No Arbitration—Public Enabled Enabled Public
11 !0x55AA Don't care External—External Arbitration—
Censored
Disabled Enabled Public
0x55AA External—External Arbitration—Public Enabled Enabled Public
’!’ = ’NOT’ Meaning any value other than the value specified
Table 13-18. PFBAPR Modification Logic
BOOTCFG
1
Censorship Control Word
EXTM
2
PFBAPR Bitfields
Writable
[0] [1] Upper Half Lower Half
0 0 0x55AA 0xXXXX 0 Yes
0 0 !0x55AA 0xXXXX 0 Yes
1 0 0x55AA 0xXXXX 0 Yes
1 0 !0x55AA 0xXXXX 0 Yes
1 1 0x55AA 0xXXXX 0 Yes
1 1 !0x55AA 0xXXXX 0 Yes
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