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Functional Description
7-14
ADSP-BF537 Blackfin Processor Hardware Reference
illustrates the general flow of the GP modes. The top of the
diagram shows an example of RX mode with 1 external frame sync. After
the PPI receives the hardware frame sync pulse (
PPI_FS1
), it delays for the
duration of the
PPI_CLK
cycles programmed into
PPI_DELAY
. The DMA
controller then transfers in the number of samples specified by
PPI_COUNT
.
Every sample that arrives after this, but before the next
PPI_FS1
frame
sync arrives, is ignored and not transferred onto the DMA bus.
a
If the next
PPI_FS1
frame sync arrives before the specified
PPI_COUNT
samples have been read in, the sample counter reinitial-
izes to 0 and starts to count up to
PPI_COUNT
again. This situation
can cause the DMA channel configuration to lose synchronization
with the PPI transfer process.
The bottom of
shows an example of TX mode, 1 internal frame
sync. After
PPI_FS1
is asserted, there is a latency of 1
PPI_CLK
cycle, and
then there is a delay for the number of
PPI_CLK
cycles programmed into
RX mode, 2 or 3 external frame syncs Input
Input
Input (if
used)
Input
RX mode, 2 or 3 internal frame syncs Output
Output
Output (if
used)
Input
TX mode, 0 frame syncs
Not used
Not used
Not used
Output
TX mode, 1 external frame sync
Input
Not used
Not used
Output
TX mode, 2 external frame syncs
Input
Input
Not used
Output
TX mode, 1 internal frame sync
Output
Not used
Not used
Output
TX mode, 2 or 3 internal frame syncs Output
Output
Output (if
used)
Output
Table 7-4. General-Purpose PPI Modes (Cont’d)
GP PPI Mode
PPI_FS1
Direction
PPI_FS2
Direction
PPI_FS3
Direction
Data
Direction
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 ...