SPI Word Lengths
10-30
ADSP-2126x SHARC Processor Hardware Reference
8-Bit Word Lengths
Eight-bit word lengths can be used when transmitting or receiving. When
transmitting, the SPI port sends out only the lower eight bits of the word
written to the SPI buffer.
For example, if the processor executes the instructions below, the SPI port
transmits
0x78
.
r0 = 0x12345678
dm(TXSPI) = r0;
When receiving, the SPI port packs the 8-bit word to the lower 32 bits of
the
RXSPI
buffer while the upper bits in the registers are zeros.
For example, if an SPI host sends the processor the 32-bit word
0x12345678
, the processor receives the following words:
0x00000078 //first word
0x00000056 //second word
0x00000034 //third word
0x00000012 //forth word
This code works only if the
MSBF
bit is zero in both the transmitter and
receiver, and the
SPICLK
frequency is small. If
MSBF
= 1 in the transmitter
and receiver, and
SPICLK
has a small frequency, the received words follow
the order
0x12
,
0x34
,
0x56
,
0x78
.
16-Bit Word Lengths
Sixteen-bit word lengths can be used when transmitting or receiving.
When transmitting, the SPI port sends out only the lower 16 bits of the
word written to the SPI buffer.
Summary of Contents for ADSP-21261 SHARC
Page 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Page 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Page 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Page 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Page 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Page 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Page 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Page 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Page 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Page 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Page 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Page 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Page 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...