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ADSP-BF537 Blackfin Processor Hardware Reference
7-35
Parallel Peripheral Interface
PPI_FRAME Register
The
PPI_FRAME
, is used in all TX and RX
modes with external frame syncs. For ITU-R 656 modes, this register
holds the number of lines expected per frame of data, where a frame is
defined as field 1 and field 2 combined, designated by the
F
indicator in
the ITU-R stream. Here, a line is defined as a complete ITU-R 656
SAV-EAV cycle.
For non-ITU-R 656 modes with external frame syncs, a frame is defined
as the data bounded between
PPI_FS2
assertions, regardless of the state of
PPI_FS3
. A line is defined as a complete
PPI_FS1
cycle. In these modes,
PPI_FS3
is used only to determine the original “frame start” each time the
PPI is enabled. It is ignored on every subsequent field and frame, and its
state (high or low) is not important except during the original frame start.
If the start of a new frame (or field, for ITU-R 656 mode) is detected
before the number of lines specified by
PPI_FRAME
have been transferred, a
frame track error results, and the
FT_ERR
bit in
PPI_STATUS
is set. How-
ever, the PPI still automatically reinitializes to count to the value
programmed in
PPI_FRAME
, and data transfer continues.
Figure 7-16. Transfer Count Register
Transfer Count Register (PPI_COUNT)
15 14
13 12 11 10
9
8
7
6
5
4
3
2
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
PPI_COUNT[15:0]
Reset = 0x0000
In RX modes, holds one less
than the number of samples to
read in to the PPI per line. In
TX modes, holds one less
than the number of samples to
write out through the PPI per
line.
0xFFC0 1008
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 ...