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ADSP-BF50x Blackfin Processor Hardware Reference
20-13
Parallel Peripheral Interface
Figure 20-6
illustrates the general flow of the general purpose PPI modes.
The top of the diagram shows an example of RX mode with one 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 sam-
ples 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.
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
Figure 20-6
shows an example of TX mode, one internal
frame sync. After
PPI_FS1
is asserted, there is a latency of one
PPI_CLK
cycle, and then there is a delay for the number of
PPI_CLK
cycles pro-
grammed into
PPI_DELAY
. Next, the DMA controller transfers out the
number of samples specified by
PPI_COUNT
. No further DMA takes place
until the next
PPI_FS1
sync and programmed delay occur.
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 20-3. General-Purpose PPI Modes (Cont’d)
GP PPI Mode
PPI_FS1
Direction
PPI_FS2
Direction
PPI_FS3
Direction
Data
Direction
Summary of Contents for EZ-KIT Lite ADSP-BF506F
Page 50: ...Contents l ADSP BF50x Blackfin Processor Hardware Reference ...
Page 92: ...Development Tools 1 30 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 110: ...Interface Overview 3 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 236: ...Internal Flash Memory Control Registers 6 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 650: ...Programming Examples 15 56 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 804: ...Programming Examples 17 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1194: ...Programming Examples 24 90 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1256: ...ACM Registers A 50 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1264: ...Boundary Scan Architecture B 8 ADSP BF50x Blackfin Processor Hardware Reference ...