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ADSP-BF537 Blackfin Processor Hardware Reference
7-21
Parallel Peripheral Interface
L
To program
PPI_FS1
and/or
PPI_FS2
for operation in an internal
frame sync mode:
1. Configure and enable DMA for the PPI. See
.
2. Configure the width and period for each frame sync signal via
TIMER0_WIDTH
and
TIMER0_PERIOD
(for
PPI_FS1
), or
TIMER1_WIDTH
and
TIMER1_PERIOD
(for
PPI_FS2
).
3. Set up
TIMER0_CONFIG
for
PWM_OUT
mode (for
PPI_FS1
). If used,
configure
TIMER1_CONFIG
for
PWM_OUT
mode (for
PPI_FS2
). This
includes setting
CLK_SEL = 1
and
TIN_SEL = 1
for each timer.
4. Write to
PPI_CONTROL
to configure and enable the PPI.
5. Write to
TIMER_ENABLE
to enable timer 0 and/or timer 1.
L
It is important to guarantee proper frame sync polarity between the
PPI and timer peripherals. To do this, make sure that if
PPI_CONTROL[15:14] = b#10
or
b#11
, the
PULSE_HI
bit is cleared in
TIMER0_CONFIG
and
TIMER1_CONFIG
. Likewise, if
PPI_CONTROL[15:14] = b#00
or
b#01
, the
PULSE_HI
bit should be
set in
TIMER0_CONFIG
and
TIMER1_CONFIG
.
To switch to another PPI mode not involving internal frame syncs:
1. Disable the PPI (using
PPI_CONTROL
).
2. Disable the timers (using
TIMER_DISABLE
).
Modes With External Frame Syncs
In RX modes with external frame syncs, the
PPI_FS1
and
PPI_FS2
pins
become edge-sensitive inputs. In such a mode, timers 1 and 2 can be used
for a purpose not involving the
TMR0
and
TMR1
pins. However, timer access
to a
TMRx
pin is disabled when the PPI is using that pin for a
PPI_FSx
frame sync input function. For modes that do not require
PPI_FS2
, timer
Содержание Blackfin ADSP-BF537
Страница 42: ...Contents xlii ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 90: ...Development Tools 1 32 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 138: ...Programming Examples 4 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 340: ...SDC Programming Examples 6 84 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 606: ...Programming Examples 9 94 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 660: ...Programming Examples 10 54 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 720: ...Electrical Specifications 11 60 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 840: ...Programming Examples 13 42 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 876: ...Programming Examples 14 36 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 938: ...Programming Examples 15 62 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 958: ...Programming Examples 17 12 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 986: ...Programming Examples 18 28 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1162: ...G 26 ADSP BF537 Blackfin Processor Hardware Reference ...
Страница 1218: ...Index I 56 ADSP BF537 Blackfin Processor Hardware Reference ...