Programming Examples
20-34
ADSP-BF50x Blackfin Processor Hardware Reference
However, the PPI still automatically reinitializes to count to the value pro-
grammed in
PPI_FRAME
, and data transfer continues.
In ITU-R 656 modes, a frame start detect happens on the falling
edge of
F
, the field indicator. This occurs at the start of field 1.
In RX mode with three external frame syncs, a frame start detect
refers to a condition where a
PPI_FS2
assertion is followed by an
assertion of
PPI_FS1
while
PPI_FS3
is low. This occurs 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
synchronize to the start of the very first frame after the PPI is
enabled. It is subsequently ignored.
When using RX mode with three external frame syncs, and only
two syncs are needed, configure the PPI for 3-frame-sync operation
and provide an external pull-down to
GND
for the
PPI_FS3
pin.
Programming Examples
The PPI can be configured to receive data from a video source in several
RX modes. The following programming examples (
Listing 20-1
through
Listing 20-5
) describe the ITU-R 656 entire field input mode.
Figure 20-17. PPI Lines Per Frame Register
PPI Lines Per Frame Register (PPI_FRAME)
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_FRAME[15:0]
Reset = 0x0000
Holds the number of lines
expected per frame of data
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 ...