ADSP-2126x SHARC Processor Hardware Reference
10-37
Serial Peripheral Interface Port
SPI Device Select Input Pin
The behavior of the
SPIDS
input depends on the configuration of the SPI.
If the SPI is a slave,
SPIDS
acts as the slave-select input. When enabled as a
master,
SPIDS
can serve as an error-detection input for the SPI in a multi-
master environment. The
ISSEN
bit (bit 4) in the
SPICTL
register enables
the SPI master mode feature. When
ISSEN
=1, the
SPIDS
input is the mas-
ter mode error input; otherwise,
SPIDS
is ignored. The state of these input
pins can be observed in the flag I/O module’s data register.
Buffering and Transmit/Receive Registers
The
TXSPI
and
RXSPI
registers are 32-bit memory-mapped registers that
hold SPI data for transmit and receive operations.
Check the buffer status before reading from or writing to these registers
because the core does not hang when it attempts to read from an empty
buffer or write to a full buffer. When the core writes to a full buffer, the
data in that buffer is overwritten and the SPI begins transmitting the new
data. Invalid data is obtained when the core reads from an empty buffer.
Figure 10-8. Single Master, Multiple Slave Configuration
MISO
SPICLK
MOSI
SPIDS
SLAVE DEVICE
MISO
SPICLK
MOSI
SPIDS
SLAVE DEVICE
MISO
SPICLK
MOSI
SPIDS
SLAVE DEVICE
MISO
SPICLK
MOSI
SPIDS
MASTER
DEVICE
FLAG
FLAG
FLAG
VDD
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 ...