Analog Devices SHARC ADSP-214 Series - 8-Bit SPI Packing

Processor Booting
23-20 ADSP-214xx SHARC Processor Hardware Reference
8-Bit SPI Packing
Figure 23-8 shows how an 8-bit SPI host packs 48-bit instructions exe-
cuted at PM addresses PMaddr0 and PMaddr1. For 8-bit hosts, four 8-bit
words pack into the shift register to generate a 32-bit word. The 32-bit
word shifts to internal program memory during the load of the
256-instruction word kernel.
The following code shows a 48-bit instruction executed:
[PMaddr0] 0x112233445566
[PMaddr1] 0x7788AABBCCDD
The 8-bit SPI host packs or prearranges the data as:
The initial boot of the 256-word loader kernel requires an 8-bit host to
transmit 1536 x 8-bit words. The SPI DMA count value of 0x180 is equal
Figure 23-8. 8-Bit SPI Slave Packing
SPI word 1 = 0x66 SPI word 7 = 0xDD
SPI word 2 = 0x55 SPI word 8 = 0xCC
SPI word 3 = 0x44 SPI word 9 = 0xBB
SPI word 4 = 0x33 SPI word 10 = 0xAA
SPI word 5 = 0x22 SPI word 11 = 0x88
SPI word 6= 0x11 SPI word 12= 0x77
SPI_MOSI_I/SPI_MISO_I
8-bit
Word N
RXSPI
DMA
Internal
Memory
32
32
32
8-bit
Word N
8-bit
Word N
8-bit
Word N
RXSR
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