Boot Assist Module (BAM)
PXN20 Microcontroller Reference Manual, Rev. 1
9-2 Freescale Semiconductor
9.1.2 Modes of Operation
The BAM has the following modes of operation:
• Normal mode
• Debug mode
• Internal-boot mode
• Serial-boot mode
9.1.2.1 Normal Mode
In normal operation the BAM responds to all read requests within its address space. The e200z6 core
executes the BAM program after the negation of RESET if the CRP_Z6VEC register value is
0xFFFF_FFFC.
9.1.2.2 Debug Mode
The BAM program is not executed when the MCU comes out of reset in OnCE debug mode. The
development tool must initialize the MCU instead of BAM before starting the user application.
9.1.2.3 Internal-Boot Mode
This mode of operation is for systems that boot from internal memory. The internal flash is used for all
code and all boot configuration data. After the BAM has completed the boot process, user code may enable
the external bus interface if required.
9.1.2.4 Serial-Boot Mode
This mode of operation can load a user program into system RAM using the eSCI or FlexCAN serial
interface, then execute the downloaded program. The user program can then be used to control the
download of data and erasing/programming of the internal or external flash memory.
9.2 Memory Map and Registers
This section provides a detailed description of the BAM memory map.
9.2.1 Module Memory Map
Table 9-1 shows the BAM memory map. The BAM ROM module occupies the last 16 KB of the MCU
memory space; however, only 4 KB is physically present. The upper 4 KB shadows the lower 4 KB. Some
important absolute addresses are presented in Table 9-1.
Table 9-1. BAM Absolute Addresses
Address Comment
0xFFFF_FFFC BAM reset vector—first executed address after the reset
0xFFFF_F000 BAM start address
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