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Boot Assist Module (BAM)
MPC5644A Microcontroller Reference Manual, Rev. 6
622
Freescale Semiconductor
21.3.3
Internal boot mode
This mode of operation is intended for systems that boot from internal flash memory. The internal flash
memory is used for all code and all boot configuration data.
21.3.4
Serial boot mode
This mode of operation is intended to load a user program into internal SRAM, using either the eSCI or
CAN serial interface, then to execute that program. The program can then be used to control the download
of data and erasing/programming of the internal or external flash memory.
21.3.5
Calibration bus boot mode
Calibration bus boot is not supported. External bus boot is supported instead.
21.4
Memory map
The BAM occupies 16 KB of memory space, 0xFFFF_C000 to 0xFFFF_FFFF. The actual code size of the
BAM program is less than 4 KB and starts at 0xFFFF_F000, repeating itself down every 4 kilobytes in the
BAM address space. The CPU starts the BAM program execution at its reset vector from address
0xFFFF_FFFC.
The BAM exits to the user code at 0xFFFF_FFF8 address. The last BAM executed instruction is a BLR.
The link register is preloaded with the user application start address. When booting from internal or
external flash, the start address is taken from next to valid RCHW 32-bit word.When the device boots
serially the start address is set according the serial boot protocol.
shows the BAM address map.
21.5
Functional description
21.5.1
BAM Program flow chart
The BAM program flow chart is shown in
.
Table 21-1. BAM memory map
Address
Description
0xFFFF_C000 – 0xFFFF_EFFF
BAM program mirrored
0xFFFF_F000 – 0xFFFF_FFFF
BAM program
0xFFFF_FFFC
Device reset vector
0xFFFF_FFF8
BAM Last executed instruction
Summary of Contents for MPC5644A
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