EXCEPTION PROCESSING STATE (INTERRUPT PROCESSING)
MOTOROLA
PROCESSING STATES
7 - 17
When either the IRQA or IRQB pin is disabled in the interrupt priority register, the inter-
rupt request coming in on the pin will be ignored, regardless of whether the input was
defined as level sensitive or edge sensitive. If the interrupt input is defined as edge sen-
sitive, its edge-detection latch will remain in the reset state for as long as the interrupt pin
is disabled. If the interrupt is defined as level-sensitive, its edge-detection latch will stay
in the reset state. If the level-sensitive interrupt is disabled while it is pending it will be
cancelled. However, if the interrupt has been fetched, it normally will not be cancelled.
The processor begins interrupt service by fetching the instruction word in the first vector
location. The interrupt is considered finished when the processor fetches the instruction
word in the second vector location.
In an edge-triggered interrupt, the internal latch is automatically cleared when the sec-
ond vector location is fetched. The fetch of the first vector location does not guarantee
that the second location will be fetched. Figure 7-3 illustrates the one case where the
second vector location is not fetched. The SWI instruction in the figure discards the fetch
of the first interrupt vector to ensure that the SWI vectors will be fetched. Instruction n4 is
decoded as an SWI while ii1 is being fetched. Execution of the SWI requires that ii1 be
discarded and the two SWI vectors (ii3 and ii4) be fetched instead.
INTERRUPT CONTROL CYCLE 1
i
i*
INTERRUPT CONTROL CYCLE 2
i
i*
FETCH
n3
n4
n5
ii1
ii3
ii4
sw1
sw2
sw3
sw4
DECODE
n2
n3
SWI
—
—
—
JSR
—
sw1
sw2
sw3
EXECUTE
n1
n2
n3
SWI
NOP
NOP
NOP
JSR
—
sw1
sw2
INSTRUCTION BEING DECODED
1
i
= INTERRUPT REQUEST
i* = INTERRUPT REQUEST GENERATED BY SWI
ii1 = FIRST VECTOR OF INTERRUPT i
ii3 = FIRST SWI VECTOR (ONE-WORD JSR)
ii4 = SECOND SWI VECTOR
n
= NORMAL INSTRUCTION WORD
n4 = SWI
sw = INSTRUCTIONS PERTAINING TO THE SWI LONG INTERRUPT ROUTINE
Figure 7-3 Interrupting an SWI
Summary of Contents for DSP56K
Page 12: ...xii LIST of TABLES MOTOROLA List of Tables Continued Table Page Number Title Number ...
Page 13: ...MOTOROLA DSP56K FAMILY INTRODUCTION 1 1 SECTION 1 DSP56K FAMILY INTRODUCTION ...
Page 31: ...MOTOROLA DATA ARITHMETIC LOGIC UNIT 3 1 SECTION 3 DATA ARITHMETIC LOGIC UNIT ...
Page 50: ...DATA ALU SUMMARY 3 20 DATA ARITHMETIC LOGIC UNIT MOTOROLA ...
Page 51: ...MOTOROLA ADDRESS GENERATION UNIT 4 1 SECTION 4 ADDRESS GENERATION UNIT ...
Page 77: ...MOTOROLA PROGRAM CONTROL UNIT 5 1 SECTION 5 PROGRAM CONTROL UNIT ...
Page 124: ...INSTRUCTION GROUPS 6 30 INSTRUCTION SET INTRODUCTION MOTOROLA ...
Page 125: ...MOTOROLA PROCESSING STATES 7 1 SECTION 7 PROCESSING STATES STOP WAIT EXCEPTION NORMAL RESET ...
Page 167: ...STOP PROCESSING STATE MOTOROLA PROCESSING STATES 7 43 ...
Page 168: ...STOP PROCESSING STATE 7 44 PROCESSING STATES MOTOROLA ...
Page 169: ...MOTOROLA PORT A 8 1 SECTION 8 PORT A ...
Page 176: ...PORT A INTERFACE 8 8 PORT A MOTOROLA ...
Page 177: ...MOTOROLA PLL CLOCK OSCILLATOR 9 1 SECTION 9 PLL CLOCK OSCILLATOR x x d Φ VCO ...
Page 191: ...10 2 ON CHIP EMULATION OnCE MOTOROLA SECTION 10 ON CHIP EMULATION OnCE ...
Page 218: ...USING THE OnCE MOTOROLA ON CHIP EMULATION OnCE 10 29 ...
Page 604: ...INSTRUCTION ENCODING A 338 INSTRUCTION SET DETAILS MOTOROLA ...
Page 605: ...MOTOROLA BENCHMARK PROGRAMS B 1 APPENDIX B BENCHMARK PROGRAMS T T T T T P1 P3 P2 P4 T T T ...
Page 609: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 5 ...
Page 611: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 7 ...
Page 613: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 9 ...
Page 615: ...BENCHMARK PROGRAMS MOTOROLA BENCHMARK PROGRAMS B 11 ...