Slave Boot Mode - Analog Devices ADSP-21261 SHARC Hardware Reference Manual

Booting
SPI word 9 = 0xBBSPI word 10 = 0xAA
SPI word 11 = 0x88SPI word 12 = 0x77
The initial boot of the 256-word loader kernel requires an 8-bit host to
transmit fifteen hundred thirty-six 8-bit words. The SPI DMA count
value of 0x180 is equal to 384 words. Since one 32-bit word is created
from four packed 8-bit words, the total number of 8-bit words transmitted
is 1536.

For all boot modes, the loader automatically outputs the correct
word width and count based on the project settings. For more
information, see the CrossCore or VisualDSP++ tools
documentation.

Slave Boot Mode

In Slave boot mode, the host processor initiates the booting operation by
activating the
SPICLK
low state. The 256-word kernel is loaded 32 bits at a time, via the SPI
Receive Shift register (
properly, the SPI DMA initially loads a DMA count of 0x180 (384)
32-bit words, which is equivalent to 0x100 (256) 48-bit words.

The processor's
Slave mode, including booting, the
sition from high to low. SPI slave booting uses the default bit
settings shown in
15-28
signal and asserting the
). To receive 256 instructions (48-bit words)
RXSR
pin should not be tied low. When in SPI
SPIDS
Table 15-9.
ADSP-2126x SHARC Processor Hardware Reference
signal to the active
SPIDS
signal is required to tran-
SPIDS