ADSP-2126x SHARC Processor Hardware Reference
15-23
System Design
to 32 bits. Therefore, for 8 or 16-bit devices, data words are packed into
the Shift register to generate 32-bit words least significant bit (LSB) first,
which are then shifted into internal memory. The relationship between
the 32-bit words received into the
RXSPI
register and the instructions that
need to be placed in internal memory is shown in
For more information about 32- and 48-bit internal memory addressing,
see
“Setting Data Access Modes” on page 5-27
.
For 16-bit SPI devices, two words shift into the 32-bit receive Shift regis-
ter (
RXSR
) before a DMA transfer to internal memory occurs. For 8-bit SPI
devices, four words shift into the 32-bit receive shift register before a
DMA transfer to internal memory occurs.
When booting, the ADSP-2126x processor expects to receive words into
the
RXSPI
register seamlessly. This means that bits are received continu-
ously without breaks.
For more information, see “Core Transmit and
Receive Operations” on page 10-12.
For different SPI host sizes, the
Figure 15-7. SPI Data Packing
32-BIT RECEIVE
SHIFT
REGISTER
S
DMA #1: DM[80000]
MSW
LSW
4
3
2
1
PM48 [0X800FF]
16
DMA #2: DM[80001]
MSW
LSW
DMA #3: DM[40002]
MSW
LSW
PM48 [0X80003]
DMA #6: DM[80005]
MSW
LSW
MOSI
256 48-BIT
WORDS
0X800FF
0X80000
DMA #4: DM[80003]
MSW
LSW
PM48 [0X80002]
DMA
P
I
R
X
PM48 [0X80001]
DMA #5: DM[80004]
MSW
LSW
PM48 [0X80000]
#384:DM[0X8017F]
MSW
LSW
#384:DM[0X8017E]
MSW
LSW
[X80001]
[X800FE]
[X80002]
LW
UW
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 ...