PXR40RM Datasheet, PDF (282/1434 Pages) Freescale Semiconductor, Inc – PXR40 Microcontroller

Boot Assist Module (BAM)
9.3.2 Debug Mode
The BAM program is not executed when the MCU exits reset in OnCE debug mode. Before accessing the
MCU resources, use the development tool to initialize the MCU.
9.3.3 Internal Boot Mode
Use this operating mode to boot from internal flash memory, which holds all of the code and configuration
data.
9.3.4 Serial Boot Mode
Use this mode to load a user program into internal SRAM, using the eSCI or CAN serial interface, then to
execute that program. The program can then control
• the download of data, and
• erasing and programming of the internal or external flash memory.
9.3.5 Development Bus Boot Mode
This boot mode is intended for packaged versions of the device that have the development bus pinned out.
The development bus (EBI) boot mode can be used for application code development.
9.4 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 every 4 KB 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. The last instruction the BAM executes is a BLR. The
link register is pre-loaded with the user application start address. The value of the start address depends on
the boot mode:
• Booting from internal or external flash — 32-bit word following a valid RCHW holds the start
address value
• Serial boot — set according to the serial boot protocol
Table 9-1 shows the BAM address map.
Table 9-1. BAM Memory Map
Address
0xFFFF_C000 – 0xFFFF_EFFF
0xFFFF_F000 – 0xFFFF_FFFF
0xFFFF_FFFC
0xFFFF_FFF8
Description
BAM program mirrored
BAM program
MCU reset vector
BAM last executed instruction
PXR40 Microcontroller Reference Manual, Rev. 1
9-2
Freescale Semiconductor