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Functional Description
7-22
ADSP-BF537 Blackfin Processor Hardware Reference
1 is not restricted in functionality and can be operated as if the PPI were
not being used (that is, the
TMR1
pin becomes available for timer use as
well). For more information on configuring and using the timers, please
refer to
Chapter 15, “General-Purpose Timers”
.
L
In RX mode with 3 external frame syncs, the start of frame detec-
tion occurs where a
PPI_FS2
assertion is followed by an assertion of
PPI_FS1
while
PPI_FS3
is low. This happens at the start of field 1.
Note that
PPI_FS3
only needs to be low when
PPI_FS1
is asserted,
not when
PPI_FS2
asserts. Also,
PPI_FS3
is only used to synchro-
nize to the start of the very first frame after the PPI is enabled. It is
subsequently ignored.
In TX modes with external frame syncs, the
PPI_FS1
and
PPI_FS2
pins are
treated as edge-sensitive inputs. In this mode, it is not necessary to config-
ure the timer(s) associated with the frame sync(s) as input(s), or to enable
them via the
TIMER_ENABLE
register. Additionally, the actual timers them-
selves are available for use, even though the timer pin(s) are taken over by
the PPI. In this case, there is no requirement that the timebase (configured
by
TIN_SEL
in
TIMERx_CONFIG
) be
PPI_CLK
.
However, if using a timer whose pin is connected to an external frame
sync, be sure to disable the pin via the
OUT_DIS
bit in
TIMERx_CONFIG
.
Then the timer itself can be configured and enabled for non-PPI use with-
out affecting PPI operation in this mode. For more information, see
Chapter 15, “General-Purpose Timers”
.
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 ...