
ADSP-2126x SHARC Processor Hardware Reference
3-53
Program Sequencer
Sensing Interrupts
For external interrupt pins
IRQ2–0
, the DSP supports two types of inter-
rupt sensitivity—edge-sensitive and level-sensitive.
The DSP detects a level-sensitive interrupt if the signal input is low
(active) when sampled on the rising edge of
CCLK
/2. A level-sensitive inter-
rupt must go high (inactive) before the processor returns from the
interrupt service routine. If a level-sensitive interrupt is still active when
the DSP samples it after returning from its service routine, the DSP treats
the signal as a new request. The DSP repeats the same interrupt routine
without returning to the main program, assuming no higher priority inter-
rupts are active.
The DSP detects an edge-sensitive interrupt if the input signal is high
(inactive) on one cycle and low (active) on the next cycle when sampled on
the rising edge of
CCLK/2
. An edge-sensitive interrupt signal can stay active
indefinitely without triggering additional interrupts. To request another
interrupt, the signal must go high, then low again.
Edge-sensitive interrupts require less external hardware compared to
level-sensitive requests, because negating the request is unnecessary. An
advantage of level-sensitive interrupts is that multiple interrupting devices
may share a single level-sensitive request line on a wired OR basis, allow-
ing easy system expansion.
The
MODE2
register controls external interrupt sensitivity as described
below.
•
Interrupt 0 Sensitivity.
Bit 0 (
IRQ0E
) directs the DSP to detect
IRQ0
as edge-sensitive (if 1) or level-sensitive (if 0).
•
Interrupt 1 Sensitivity.
Bit 1 (
IRQ1E
) directs the DSP to detect
IRQ1
as edge-sensitive (if 1) or level-sensitive (if 0).
•
Interrupt 2 Sensitivity.
Bit 2 (
IRQ2E
) directs the DSP to detect
IRQ2
as edge-sensitive (if 1) or level-sensitive (if 0).
Содержание ADSP-21261 SHARC
Страница 30: ...Contents xxx ADSP 2126x SHARC Processor Hardware Reference ...
Страница 40: ...Register Diagram Conventions xl ADSP 2126x SHARC Processor Hardware Reference ...
Страница 58: ...Differences From Previous SHARCs 1 18 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 112: ...Secondary Processing Element PEy 2 54 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 178: ...Summary 3 66 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 204: ...DAG Instruction Summary 4 26 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 322: ...Setting Up DMA 7 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 436: ...SPORT Programming Examples 9 86 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 521: ...ADSP 2126x SHARC Processor Hardware Reference 11 31 Input Data Port rts IDP_ISR end ...
Страница 522: ...Input Data Port Programming Example 11 32 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 590: ...Timer Programming Examples 14 20 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 796: ...I O Processor Registers A 174 ADSP 2126x SHARC Processor Hardware Reference ...
Страница 800: ...B 4 ADSP 2126x SHARC Processor Core Manual ...
Страница 846: ...Index I 36 ADSP 2126x SHARC Processor Hardware Reference ...