Information Manual
DSP1611/17/18/27/28/29 DIGITAL SIGNAL PROCESSOR
April 1998
Parallel I/O (DSP1617 Only)
Lucent Technologies Inc.
DRAFT COPY
8-19
(continued)
8.2.3 Power Management
Bit 5 of the powerc register (PIO1DIS) is a powerdown signal to the PIO I/O unit. It disables the clock input to the
unit, thus eliminating any sleep power associated with the PIO. Because the gating of the clocks can result in
incomplete transactions, it is recommended that this option be used in applications where the PIO is not used or if
reset can be used to reenable the PIO unit. Otherwise, the first transaction after reenabling the unit might be cor-
rupted.
8.3 Interrupts and the PIO
PIO events can generate two internal interrupts. An internal interrupt is generated (provided it is unmasked) if an
external device performs a passive mode write. If the external device drives PIDS high, an internal interrupt
request is generated. When the DSP accepts this interrupt request, the IACK signal is asserted. When the inter-
rupt routine is completed, IACK is negated (becomes logic 0). Similarly, if an external device performs a passive
read, an internal interrupt request is generated after PODS is driven high. When the DSP accepts this interrupt
request, the IACK signal is asserted. When the interrupt routine has completed, IACK is negated (becomes logic
0). See
, for more information on how the DSP reacts to interrupts.
If the DSP is in the passive mode, the interrupt mechanism synchronizes a data source with the program being run
by the DSP. A data source provides data to the DSP via passive writes. During the associated interrupt routine,
the DSP program performs I/O functions. The receipt of data and the conclusion of the interrupt service routine by
the DSP is indicated to the external data source by the falling edge (high-to-low) transition of the IACK signal.
If the PIDS signal is active, the pdx[IN] register is shadowed during interrupts. This allows the parallel input to be
used during interrupts without the possibility of destroying data previously fetched via a latent PIO read. When the
interrupt service routine is exited, pdx[IN] is loaded with its previous value (prior to the interrupt). If the parallel
input is changed from active to passive during the interrupt, the shadowing feature is disabled.
Interrupts Controlled by the pioc: (also controlled by the inc register)
Interrupts caused by an external device writing to the DSP's serial port. This type of interrupt is masked if bit 9 of
the pioc register is set to logic 0.
Interrupts caused by an external device reading from the DSP's serial port. This type of interrupt is masked if bit
8 of the pioc register is set to logic 0.
Interrupts caused by an external device writing to the DSP's parallel port i the DSP is in passive mode. This type
of interrupt is masked if bit 7 of the pioc register is set to logic 0.
Interrupts caused by an external device reading from the DSP's parallel port if the DSP is in passive mode. This
type of interrupt is masked if bit 6 of the pioc register is set to logic 0.
Interrupts caused by an external device asserting the INT0 pin. This type of interrupt is masked if bit 5 of the
pioc register is set to logic 0.
If the five above interrupts are enabled in the pioc and not in the inc register, they will operate in a mode compati-
ble with the DSP16A (i.e., all vectored to location 0x1). If enabled in the inc register, they vector to separate loca-
tions (see
).
Содержание DSP1611
Страница 18: ...Chapter 1 Introduction...
Страница 27: ...Chapter 2 Hardware Architecture...
Страница 52: ...Chapter 3 Software Architecture...
Страница 116: ...Chapter 4 Instruction Set...
Страница 154: ...Chapter 5 Core Architecture...
Страница 176: ...Chapter 6 External Memory Interface...
Страница 208: ...Chapter 7 Serial I O...
Страница 237: ...Chapter 8 Parallel I O DSP1617 Only...
Страница 261: ...Chapter 9 Parallel Host Interface PHIF DSP1611 18 27 28 29 Only...
Страница 275: ...Chapter 10 Bit I O Unit...
Страница 284: ...Chapter 11 JTAG Test Access Port...
Страница 306: ...Chapter 12 Timer...
Страница 313: ...Chapter 13 Bit Manipulation Unit...
Страница 325: ...Chapter 14 Error Correction Coprocessor DSP1618 28 Only...
Страница 350: ...Chapter 15 Interface Guide...
Страница 367: ...Appendix A Instruction Encoding...
Страница 379: ...Appendix B Instruction Set Summary...
Страница 381: ...aD extractz aS IM16 B 52 aD insert aS arM B 53 aD insert aS IM16 B 54 aD aS aaT B 55...
Страница 437: ...Index...