Basic Booting Process
24-22
ADSP-BF50x Blackfin Processor Hardware Reference
With the
BFLAG_FIRST
flag set, the
ARGUMENT
field functions as the
next-DXE pointer. This is a relative pointer to the next free source address
or to the next DXE start address in a multi-DXE stream.
Direct Code Execution
Applications may want to avoid long booting times and start code execu-
tion directly from 16-bit flash. This feature is called direct code execution.
This is a special case of boot termination that replaces the no-boot/bypass
mode in the ADSP-BF53x Blackfin processors.
An initial boot block header is needed for the processor to fetch and exe-
cute program code from the boot device as early as possible. The safety
mechanisms of the block, such as the header signature and the XOR
checksum, avoid unpredictable processor behavior due to the boot mem-
ory not being programmed with valid data yet. The boot kernel first loads
the first block header and checks it for consistency. If the block header is
corrupted, the boot kernel goes into a safe idle state and does not start
code execution.
If the initial block header checks good, the boot kernel interrogates the
block flags. If the block has the
BFLAG_FINAL
flag set, the boot kernel
immediately terminates and jumps directly to the address stored in the
EVT1
register. To cause the boot kernel to customize the
EVT1
register in
advance, the initial blocks must also have the
BFLAG_FIRST
flag set. The
TARGET ADDRESS
field is then copied to the
EVT1
register. In this way, the
TARGET ADDRESS
field of the initial block defines the start address of the
application.
BYTE COUNT
0x0000 0100
256 bytes of code
ARGUMENT
0x0000 0100
Functions as next-DXE pointer in multi-DXE boot streams
Table 24-5. Header for a Single Block Boot Stream (Cont’d)
Field
Value
Comments
Содержание EZ-KIT Lite ADSP-BF506F
Страница 50: ...Contents l ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 92: ...Development Tools 1 30 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 110: ...Interface Overview 3 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 132: ...Unique Information for the ADSP BF50x Processor 4 22 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 236: ...Internal Flash Memory Control Registers 6 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 342: ...Unique Information for the ADSP BF50x Processor 7 106 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 484: ...Unique Information for the ADSP BF50x Processor 10 60 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 493: ...ADSP BF50x Blackfin Processor Hardware Reference 11 9 Core Timer Unique Information for the ADSP BF50x Processor None ...
Страница 494: ...Unique Information for the ADSP BF50x Processor 11 10 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 506: ...Unique Information for the ADSP BF50x Processor 12 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 544: ...Unique Information for the ADSP BF50x Processor 13 38 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 650: ...Programming Examples 15 56 ADSP BF50x Blackfin Processor Hardware Reference ...
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Страница 972: ...Unique Information for the ADSP BF50x Processor 20 38 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 1194: ...Programming Examples 24 90 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 1256: ...ACM Registers A 50 ADSP BF50x Blackfin Processor Hardware Reference ...
Страница 1264: ...Boundary Scan Architecture B 8 ADSP BF50x Blackfin Processor Hardware Reference ...