Interrupts With and Without Nesting
4-54
ADSP-BF535 Blackfin Processor Hardware Reference
The return-from-interrupt instruction,
RTI
, is sensitive to the state of
RETI[0]
and
SNEN
. When both
RETI[0]
and
SNEN
are set,
RTI
clears only
the global disable bit
IPEND[4]
. However, when self-nesting mode is dis-
abled (
SNEN = 0
),
RTI
clears both
IPEND[4]
and the
IPEND
bit that
corresponds to the current interrupt level.
The
SNEN
bit should be set once in the reset service routine and not
changed again during normal interrupt processing.
Since the LSB of the RETI register is used to store the self-nesting state,
avoid changing the contents of the RETI register when self-nesting is
enabled, except for saving and restoring the register to the stack.
Exception Handling
Interrupts and exceptions treat instructions in the pipeline differently:
• When an interrupt occurs, all instructions in the pipeline are
aborted.
• When an exception occurs, all instructions in the pipeline after the
excepting instruction are aborted. For service exceptions, the
excepting instruction is also aborted.
Because exceptions, NMIs, and emulation events have a dedicated return
register, guarding the return address is optional. Consequently, the push
and pop instructions for exceptions, NMIs, and emulation events do not
affect the interrupt system.
Note, however, the return instructions for exceptions (
RTX
,
RTN
, and
RTE
)
do clear the least significant bit currently set in
IPEND
.
Содержание ADSP-BF535 Blackfin
Страница 80: ...Development Tools 1 26 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 312: ...Working With Memory 6 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 332: ...System Interfaces 7 20 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 360: ...Dynamic Power Management Controller 8 28 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 446: ...Beginning and Ending an SPI Transfer 10 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 522: ...Timing Examples 11 76 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 562: ...IrDA Support 12 40 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 608: ...PCI I O Issues 13 46 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 672: ...References 14 64 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 810: ...SDRAM Controller SDC 18 86 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 811: ...ADSP BF535 Blackfin Processor Hardware Reference 18 87 External Bus Interface Unit...
Страница 812: ...SDRAM Controller SDC 18 88 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 860: ...DMA Bus Debug Registers 20 30 ADSP BF535 Blackfin Processor Hardware Reference...
Страница 908: ...SDRAM Controller External Bus Interface Unit B 36 ADSP BF535 Blackfin Processor Hardware Reference...