Boot Assist Module (BAM)MPC5644A Microcontroller Reference Manual, Rev. 6626 Freescale SemiconductorFigure 21-3. Serial boot flash passwordA valid serial password must be always programmed, regardless the boot mode used. This providescapability to “rescue” the part using the serial boot mode, if the flash content becomes corrupted forwhatever reason.21.5.3 Reset configuration half word (RCHW)The Reset Configuration Half Word defines boot options and has to be programmed by the user topredefined locations in the internal flash or at the beginning of the external flash device. The next 32-bitword after the RCHW has to be programmed with a starting address of the user application. The BAMprogram uses this location to fetch the address, where it passes control to.Table 21-6 provides possible RCHW locations in the internal flash. When booting from the external flashdevice, the RCHW should reside in the very first 16-bit half word of the flash.Figure 21-4 shows the fields of the RCHW.Figure 21-4. Reset configuration half wordFlash Password @ 0x00FF_FDD8 - 0x00FF_FDDF63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 481 1 1 1 1 1 1 0 1 1 1 0 1 1 0 1Serial Boot Password (0x00FF_FDD8) - 0xFEED (Factory Default)47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 321 1 1 1 1 0 1 0 1 1 0 0 1 1 1 0Serial Boot Password (0x00FF_FDDA) - 0xFACE (Factory Default)31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 161 1 0 0 1 0 1 0 1 1 1 1 1 1 1 0Serial Boot Password (0x00FF_FDDC) - 0xCAFE (Factory Default)15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 01 0 1 1 1 1 1 0 1 1 1 0 1 1 1 1Serial Boot Password (0x00FF_FDDE) - 0xBEEF (Factory Default)BOOT_BLOCK_ADDRESS0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15SWT WTE PS0 VLE 0 1 0 1 1 0 1 0Boot Identifier = 0x5A
