ADSP-2126x SHARC Processor Hardware Reference
9-73
Serial Ports
were reading an empty buffer that is currently active. This locks up the
core until the SPORT is reset.
Therefore, set the Direction bit, the Serial Port Enable bit, and DMA
Enable bits before initiating any operations on the SPORT data buffers. If
the DSP operates on the inactive transmit or receive buffers while the
SPORT is enabled, it can cause unpredictable results.
SPORT DMA Chaining
In chained DMA operations, the processor’s DMA controller automati-
cally sets up another DMA transfer when the contents of the current
buffer have been transmitted (or received). The Chain Pointer register
(
CPSPxy
) functions as a pointer to the next set of buffer parameters stored
in memory. The DMA controller automatically downloads these buffer
parameters to set up the next DMA sequence. For more information on
SPORT DMA chaining, see
“Setting Up DMA Parameter Registers” on
.
DMA chaining occurs independently for the transmit and receive channels
of each serial port. Each SPORT DMA channel has a chaining enable bit
(
SCHEN_A
or
SCHEN_B
) that when set (= 1) enables DMA chaining and
when cleared (= 0) disables DMA chaining. Writing all zeros to the
address field of the chain pointer register (
CPSPxy
) also disables chaining.
Single Word Transfers
Individual data words may also be transmitted and received by the serial
ports, with interrupts occurring as each 32-bit word is transmitted or
received. When a serial port is enabled and DMA is disabled, the SPORT
interrupts are generated whenever a complete 32-bit word has been
received in the receive buffer, or whenever the transmit buffer is not full.
Note that both channel A and B buffers share the same interrupt vector.
Single word interrupts can be used to implement interrupt-driven I/O on
the serial ports.
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 ...