NXP Semiconductors MPC5606S - ITU-R BT.656 Sync Information Extraction

Display Control Unit (DCU)
MPC5606S Microcontroller Reference Manual, Rev. 7
Freescale Semiconductor 437
12.8.1 ITU-R BT.656 sync information extraction
According to ITU-R BT.656 recommendation, the incoming digital video will have a pdi_clk signal and 8
data bits. The data bits can contain both the video data and the timing reference signals (VSYNC and
HSYNC).
The timing signals are encoded at the start and end of each line by timing reference codes known as Start
of Active Video (SAV) and End of Active Video (EAV). The SAV and EAV codes are identified by their
preamble of three bytes (0xFF, 0x00, 0x00). Due to this, neither 0x00 or 0xFF can be used during the
Active Video Data. The preamble is followed by the XY status word which contains a field bit (F), a
vertical blanking bit (V), a horizontal blanking bit (H), and four protection bits for single-bit error
correction and detection.
The H bit is set to one to denote an EAV. That is the end of a line, and the beginning of the horizontal
blanking period. The V bit is set to 1 to denote the beginning of the vertical blanking period. The F bit is
used for interlaced video to denote if the forthcoming line is odd or even.
The remaining 4 bits make up the protection bits for single-bit error correction and detection. F and V
fields are only allowed to change as part of EAV sequences i.e during transitions from H=0 to H=1.
An entire line of video comprises Active Video + Horizontal Blanking (from the start of the EAV code
until the end of the SAV code) and Vertical Blanking (the space where V = 1).
Figure 12-80. ITU-R BT.656 8-bit parallel data format for 525 video system
NOTE
Only 8-bit video is supported on this device.
Only non-interlaced video is supported on this device. The Field (F) value
is ignored. For more information, please see EB736, Limitations of the PDI
Module on the MPC560xS.
Table 12-65. Control byte sequence for 8-bit video
Data Bit
First word
(FF)
Second word
(00)
Third word
(00)
Fourth word
(XY
D9(MSB) 1 0 0 1
D8 1 0 0 F
D7 1 0 0 V
F
F
0
0
0
0
X
Y
8
0
1
0
8
0
1
0
8
0
1
0
F
F
0
0
0
0
X
Y
Video Data
Active
EAV code
SAV code
blanking
H Control Signal
Start of
Digital line
Start of
digital Active Line
Next Line