Boot Assist Module (BAM)MPC5566 Microcontroller Reference Manual, Rev. 2Freescale Semiconductor 16-5The boot mode determines the following:• Enables or disables internal flash memory• Enables or disables the Nexus port• Compares the password received in serial boot mode to a preset public password or aprogrammable password located in internal flashTable 16-3 summarizes the different boot modes.The 32-bit censorship word, which contains the censorship control and serial boot control fields, is readand interpreted during the boot process. Its value is used in conjunction with the BOOTCFG[0:1] valuesto enable or disable the internal flash memory and the Nexus interface. The censorship word isprogrammed at the factory to contain 0x55AA_55AA, which uses a password in internal flash to activateserial boot mode for an uncensored (public) device.Table 16-3. Boot ModesBOOTCFG[0:1]CensorshipControl0x00FF_FDE0Serial BootControl0x00FF_FDE2Boot Mode NameInternalFlashStateNexusStateSerialPassword00 !0x55AA11 ‘!’ = ‘NOT,’ as in !0x55AA, which means all values except 0x55AA. Do not use 0x0000 or 0xFFFF for the value of thecensorship control or serial boot control words.Any value Internal—Censored Enabled Disabled Flash0x55AA Internal—Public Enabled Enabled Public01 Any value 0x55AA Serial—Flash password Enabled Disabled Flash!0x55AA Serial—Public password Disabled Enabled Public10 !0x55AA Any value External—No arbitration—Censored Disabled Enabled Public0x55AA External—No arbitration—Public Enabled Enabled Public11!0x55AAAny valueExternal—External arbitration—CensoredDisabled Enabled Public0x55AA External—External arbitration—PublicEnabled Enabled Public
