Boot Assist Module (BAM)
MPC5510 Microcontroller Family Reference Manual, Rev. 1
Freescale Semiconductor
32-3
Preliminary
32.2.2
Register Descriptions
The BAM module does not have any registers.
32.3
Functional Description
32.3.1
BAM Program Resources
The BAM program uses/initializes these MCU resources:
•
The BOOTCFG field in the reset status register (SIU_RSR) determines the boot mode
•
The location and value of the reset configuration halfword (RCHW) determines the location of the
boot code and the boot configuration options
•
FlexCAN_A and eSCI _A modules for serial boot mode
•
FlexCAN_A message buffers RAM for stack and global variables during serial boot mode
•
The DISNEX bit in the SIU_CCR register to determine if the Nexus port is enabled
The BAM program:
•
Configures the e200z1 MMU to allow access to all available MCU address space (internal flash,
EBI, peripheral bridge, and SRAM) without address translation
•
Configures FlexCAN_A and eSCI_A when performing serial boot mode
•
Uses the eDMA during serial boot mode.
32.3.2
BAM Program Operation
If the CRP_Z1VEC register remains in its POR state, the BAM code is executed after the negation of reset
and before user code starts. To prevent the execution of the BAM code upon exiting sleep mode, change
the value of the CPR_Z1VEC register before entering the sleep mode. See
,” in
Chapter 5, “Clock, Reset, and Power Control (CRP)
,” for more detail
about the CRP_Z1VEC register.
The BAM reads the status of the BOOTCFG bit from the reset status register (SIU_RSR) and the
appropriate boot sequence is started (see
). The BOOTCFG bit reflects state of the BOOTCFG
pin during the MCU reset.
shows the boot mode selection depending on BOOTCFG bit in the SIU_RSR, how the value
stored in the Censorship word in the shadow row of internal flash memory effects whether the internal
flash memory is enabled or disabled, whether the Nexus port is enabled or disabled, and whether the
password downloaded in serial boot mode is compared to a fixed public password or to a user program-
Table 32-1. BAM Absolute Addresses
Address
Comment
0xFFFF_FFFC
BAM reset vector—first executed address after the reset
0xFFFF_F000
BAM start address