VisualDSP++ 4.5 Loader and Utilities Manual - Analog Devices

Loader/Splitter for Blackfin Processors
ADSP-BF561/BF566 Processor Initialization Blocks
The initialization block or a second-stage loader utility must be used to
initialize the SDRAM memory of the ADSP-BF561/BF566 processor
before any instructions or data are loaded into it.
The initialization blocks are identified by a bit in the flag word of the
10-byte block header. When the boot ROM encounters the initialization
blocks in the boot stream, it loads the blocks and executes them immediately.
The initialization blocks must save and restore registers and return
to the boot ROM, so the boot ROM can load the rest of the blocks. For
more details, see
“ADSP-BF531/BF532/BF533/BF534/BF536/BF537/BF538/ BF539
Blocks, Block Headers, and Flags” on page 2-33.
Both the initialization block and second-stage loader utility can be used to
force the boot ROM to load a specific .dxe file from the external memory
device if the boot ROM stores multiple executable files. The initialization
block can manipulate the R0 or R3 register, which the boot ROM uses as
the external memory pointers for flash/PROM or SPI memory boot,
respectively.
After the processor returns from the execution of the initialization blocks,
the boot ROM continues to load blocks from the location specified in the
R0 or R3 register, which can be any .dxe file in the boot stream. This
option requires the starting locations of specific executables within external
memory. The R0 or R3 register must point to the 10-byte count header,
as illustrated in “ADSP-BF53x and ADSP-BF561/BF566 Multi-Application
(Multi-DXE) Management” on page 2-51.
VisualDSP++ 4.5 Loader and Utilities Manual 2-49