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ADSP-2126x SHARC Processor Hardware Reference
commonly used in digital filters and Fourier transforms. The DAGs auto-
matically handle address pointer wraparound, reducing overhead,
increasing performance, and simplifying implementation.
Interrupts.
The ADSP-2126x has three external hardware interrupts. The
processor also provides three general-purpose interrupts, and a special
interrupt for reset. The processor has internally-generated interrupts for
the timer, DMA controller operations, circular buffer overflow, stack
overflows, arithmetic exceptions, and user-defined software interrupts.
For the general-purpose interrupts and the internal timer interrupt, the
ADSP-2126x automatically stacks the arithmetic status (
ASTATx
) register
and mode (
MODE1
) registers in parallel with the interrupt servicing, allow-
ing 15 nesting levels of very fast service for these interrupts.
Context Switch.
Many of the processor’s registers have secondary registers
that can be activated during interrupt servicing for a fast context switch.
The data registers in the register file, the DAG registers, and the multiplier
result register all have secondary registers. The primary registers are active
at reset, while the secondary registers are activated by control bits in a
mode control register.
Timer.
The core’s programmable interval timer provides periodic inter-
rupt generation. When enabled, the timer decrements a 32-bit count
register every cycle. When this count register reaches zero, the
ADSP-2126x generates an interrupt and asserts its timer expired output.
The count register is automatically reloaded from a 32-bit period register
and the countdown resumes immediately.
Instruction Cache.
The program sequencer includes a 32-word instruc-
tion cache that effectively provides three-bus operation for fetching an
instruction and two data values. The cache is selective; only instructions
whose fetches conflict with data accesses using the PM bus are cached.
This caching allows full speed execution of core, looped operations such as
digital filter multiply-accumulates, and FFT butterfly processing. For
more information on the cache, refer to
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 ...