NXP Semiconductors MPC5566 - Single Bus Master or Multiple Bus Masters

Boot Assist Module (BAM)
MPC5566 Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 16-9
16.3.2.2.2 Single Bus Master or Multiple Bus Masters
External boot mode has two options for booting:
• External boot with no arbitration — Use this mode for single-master systems where the MCU is
the only bus master, therefore no arbitration of the external bus is necessary. Refer to
Section 16.3.2.2.3, “Configure the EBI for External Boot—Single Master with no Arbitration.”
• External boot with external arbitration — Use this mode for multi-master systems where more than
one bus master uses the external bus and bus arbitration is handled external to the MCU. Refer to
Section 16.3.2.2.4, “Configure the EBI for External Boot with External Arbitration Mode.”
In a multi-master system where both masters boot from the same external bus memory, configure one
master to use external boot with no arbitration mode, and configure all other masters to boot using external
boot with external arbitration mode. The EBI configuration differs for these modes.
The boot modes are specified by the BOOTCFG[0:1] value. Refer to the following section for more
information:
Section 12.4.2.10, “Bus Operation in External Master Mode”
16.3.2.2.3 Configure the EBI for External Boot—Single Master with no Arbitration
The BAM program configures:
• Chip select CS[0] as a 16-bit port starting at base address 0x2000_0000 with:
— no burst
— 15 wait states
—8MB
• EBI for no external master (clears EXTM bit)
• Enables the EBI for normal operation
• Configures the following EBI signals:
— ADDR[8:31]
— DATA[0:15]
—WE
[0]
—OE
—TS
—CS[0]
16.3.2.2.4 Configure the EBI for External Boot with External Arbitration Mode
NOTE
Some signals listed in this section are not implemented on all device
packages. Refer to Chapter 12, “External Bus Interface (EBI),” for more
information.
To use external boot mode with external arbitration, the BAM program must also configure the following
bits in addition to the bits set for External Boot with no Arbitration mode: