ADSP-BF535 Blackfin Processor Hardware Reference
15-1
15 PROGRAMMABLE FLAGS
The ADSP-BF535 processor supports sixteen bidirectional programmable
flags (
PFx
) or general-purpose I/O pins,
PF[15:0]
. Each pin can be indi-
vidually configured as either an input or an output by using the Flag
Direction register (
FIO_DIR
). When configured as an output, the state
written to the Flag Set (
FIO_FLAG_S
) and Flag Clear (
FIO_FLAG_C
) registers
determines the state driven by the output
PFx
pin. Reading either the Flag
Set or Flag Clear register returns the state of each pin, regardless of
whether each individual pin is configured as an input or an output.
Each
PFx
pin can be further configured to generate an interrupt. When a
PFx
pin is configured as an input, an interrupt can be generated according
to the state of the pin (either high or low), an edge transition (low to high
or high to low), or on both edge transitions (low to high and high to low).
Input sensitivity is defined on a per-bit basis by the Flag Polarity register
(
FIO_POLAR
), the Flag Interrupt Sensitivity register (
FIO_EDGE
) and the
Flag Set on Both Edges register (
FIO_BOTH
). When a
PFx
pin is configured
as an output, enabling interrupts for the pin allows an interrupt to be gen-
erated by setting the
PFx
pin.
The ADSP-BF535 processor provides two independent interrupt channels
for the
PFx
pins. Identical in functionality, these are called Interrupt A
and Interrupt B. Each interrupt has two mask registers associated with it, a
Flag Interrupt Mask Set register (
FIO_MASKx_S
) and a Flag Interrupt Mask
Clear register (
FIO_MASKx_C
). This flexible mechanism allows each bit to
generate Flag Interrupt A, Flag Interrupt B, both Flag Interrupts A and B,
or neither.
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...