NXP Semiconductors MPC5644A Reference Manual page 624

Boot Assist Module (BAM)
TLB
Region
entry
0 Peripheral Bridge B
1 Internal Flash
2
3 Internal SRAM
4 Peripheral Bridge A
1
This device has only a single peripheral bridge, but to match the memory map of other devices in the MPC5500
family the peripherals are mapped to appear as if they are on two different peripheral bridges.
The MMU regions are mapped with logical address the same as physical address except for the external
bus interface (EBI). The logical EBI address space is mapped to physical address space of the internal
Flash memory. This allows code, written to run from external memory, to be executed from internal Flash.
After the MMU configuration, the BAM program checks the BOOTCFG field of the reset status register
(SIU_RSR) and the appropriate boot sequence is started as shown in
Depending on the values stored in the censorship word and serial boot control word in the shadow row of
the internal Flash memory, the internal Flash memory can be enabled or disabled, the Nexus port can be
enabled or disabled, the password received in the serial boot mode is compared with the fixed public
password or compared to a user programmable password in the internal Flash memory.
Censorship
BOOTCFG control
[0:1] 0x00FF_FDE
0
!0x55AA
00
0x55AA
01 Any value
624
Table 21-2. MMU configuration for internal flash boot
Logical
base address
1
and BAM 0xFFF0_0000
0x0000_0000
EBI 0x2000_0000
0x4000_0000
1
0xC3F0_0000
Table 21-3. Boot modes
Serial boot
control
0x00FF_FDE
2
1
Internal—Censored
Any value
Internal—Public
0x55AA Serial—Flash password
!0x55AA Serial—Public password
MPC5644A Microcontroller Reference Manual, Rev. 6
Physical
base address
0xFFF0_0000
0x0000_0000
0x0000_0000
0x4000_0000
0xC3F0_0000
Table
Internal
Boot mode name
Enabled Disable
Enabled Enabled
Enabled Disable
Size Attributes
1 MB Guarded
Big endian
Global PID
16 MB Not guarded
Big endian
Global PID
16 MB Not guarded
Big endian
Global PID
256 KB Not guarded
Big endian
Global PID
1 MB Guarded
Big endian
Global PID
21-3.
Nexus Serial
Flash
state password
state
Flash
d
Public
Flash
d
Disable Enabled Public
d
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