VisualDSP++ 4.5 Loader and Utilities Manual - Analog Devices

ADSP-2126x/2136x/2137x Processor Booting
Table 5-10. Default Settings for PROM and SPI Boot Modes
Boot Type
Selection
Host
Width
Booting From an SPI Flash
Output Format Bit Reverse Initial Word
-bprom 8 Intel hex No -
-bspislave 32 ASCII No -
-bspiflash 32 ASCII No -
-bspimaster 32 ASCII No 0x000000a5
-bspiprom 8 Intel Hex Yes 0xa5
For SPI flash devices, the format of the boot stream is identical to that
used in SPI slave mode, with the first byte of the boot stream being the
first byte of the kernel. This is because SPI flash devices do not drive out
data until they receive an 8-bit command and a 24-bit address.
Booting From an SPI PROM (16-bit address)
Figure 5-2 shows the initial 32-bit word sent out from the processor from
the perspective of the serial PROM device.
As shown in Figure 5-2, SPI EEPROMs only require an 8-bit opcode and
a 16-bit address. These devices begin transmitting on clock cycle 24.
However, because the processor is not expecting data until clock cycle 32,
it is necessary for the loader to pad an extra byte to the beginning of the
boot stream when programming the PROM. In other words, the first byte
of the boot kernel is the second byte of the boot stream. The VisualDSP++
tools automatically handles this in the loader file generation process for
SPI PROM devices.
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