System Operating Details
3-44
Table 3-15. External Memory Boot Table for 32-Bit Boot Download (Continued)
Word Address
(16-bit word)
Contents
2nd word of 2nd section to transfer
.....
N2th word of 2nd section to transfer
.....
Number of elements of the last section to transfer = NL
Most significant word of destination address for the last section. Can be 0, 1, or 2.
Least significant word of destination address for the last section. Can be from
0000h to FFFFh.WA
1st word of last section to transfer
2nd word of last section to transfer
.....
NLth word of last section to transfer
0000h to indicate the end of source program
3.10.4.3
Bootloader Description
When the MPU releases the DSP subsystem from reset, if pins
BOOT_MOD[3:0] = 0000, then the address 0xFFFF00 is mapped into external
memory space. If pins BOOT_MOD[3:0]
≠
0000, then the address 0xFFFF00
maps to internal ROM that has vector to the bootloader at 0xFF800. At this
point the bootloader starts to execute. It checks to see if the DSP subsystem
in is SAM. If not, it keeps checking indefinitely. As soon as it is in SAM, it does
the following initialization:
-
Setup stack pointer (stack size is set to 0x20, default stack mode is fast
dual stack)
-
Disable interrupts globally
-
Mask off interrupts
-
Setup EMIF
After this is done, the bootloader starts to check the BOOT_MOD[3:0] bits of
the DSP_BOOT_CONFIG register. Depending on the bit combination, it then
boots the DSP subsystem.