adv601lc Analog Devices, Inc., adv601lc Datasheet - Page 20

• Manufacturer Part Number: adv601lc
• Description: Ultralow Cost Video Codec
• Manufacturer: Analog Devices, Inc.

Name
CCIR-656
Multiplex Philips
Video Formats—CCIR-656
The ADV601LC supports a glueless video interface to CCIR-656
devices when the Video Format is programmed to CCIR-656
mode. CCIR-656 requires that 4:2:2 data (8 bits per compo-
nent) be multiplexed and transmitted over a single 8-bit physical
interface. A 27 MHz clock is transmitted along with the data.
This clock is synchronous with the data. The color space of
CCIR-656 is YCrCb.
When in master mode, the CCIR-656 mode does not require
any external synchronization or blanking signals to accompany
digital video. Instead, CCIR-656 includes special time codes in
the stream syntax that define horizontal blanking periods, verti-
cal blanking periods, and field synchronization (horizontal and
vertical synchronization information can be derived). These
time codes are called End-of-Active-Video (EAV) and Start-of-
Active-Video (SAV). Each line of video has one EAV and one
SAV time code. EAV and SAV have three bits of embedded
information to define HSYNC, VSYNC and Field information
as well as error detection and correction bits.
ADV601LC
Clocks and Strobes
All video data is synchronous to the video clock (VCLK).
The rising edge of VCLK is used to clock all data into the
ADV601LC.
Synchronization and Blanking Pins
Three signals, which can be configured as inputs or outputs, are
used for video frame and field horizontal synchronization and
blanking. These signals are VSYNC, HSYNC, and FIELD.
VDATA Pins Functions With Differing Video Interface Formats
The functionality of the Video Interface pins depends on the
current video format. Table VIII defines how Video data pins
are used for the various formats.
HSYNC, VSYNC and FIELD
Functionality for CCIR-656
Encode Mode (video data is input
Decode Mode (video data is output
to the chip)
from the chip)
Table IX. CCIR-656 Master and Slave Modes HSYNC, VSYNC, and FIELD Functionality
Bit/
Component
8
8
Master Mode (HSYNC, VSYNC
and FIELD Are Outputs)
Pins are driven to reflect the states of the
received time codes: EAV and SAV. This
functionality is independent of the state of
the 525-625 mode control. An encoder is
most likely to be in master mode.
Pins are output to the precise timing definitions
for CCIR-656 interfaces. The state of the pins
reflect the state of the EAV and SAV timing
codes that are generated in the output video data.
These definitions are different for 525 and 625 line
systems. The ADV601LC completely manages the
generation and timing of these pins.
Color
Space
YCrCb
YUV
Table VII. Component Digital Video Formats
Sampling
4:2:2
4:2:2
–20–
VCLK is driven with a 27 MHz, 50% duty cycle clock which is
synchronous with the video data. Video data is clocked on the
rising edge of the VCLK signal. When decoding, the VCLK
signal is typically transmitted along with video data in the
CCIR-656 physical interface.
Electrically, CCIR-656 specifies differential ECL levels to be
used for all interfaces. The ADV601LC, however, only supports
unipolar, TTL logic thresholds. Systems designs that interface
to strictly conforming CCIR-656 devices (especially when inter-
facing over long cable distances) must include ECL level shifters
and line drivers.
The functionality of HSYNC, VSYNC and FIELD Pins is
dependent on three programmable modes of the ADV601LC:
Master-Slave Control, Encode-Decode Control and 525-625
Control. Table IX summarizes the functionality of these pins in
various modes.
VDATA[7:0] Pins
7
6
5
4
3
2
1
0
Table VIII. VDATA[7:0] Pin Functions Under CCIR-656
and Multiplex Philips
Nominal
Data Rate
(MHz)
27
<=29.5
Slave
Master/
Master
Either
CCIR-656
Data9
Data8
Data7
Data6
Data5
Data4
Data3
Data2
Slave Mode (HSYNC, VSYNC
and FIELD Are Inputs)
Undefined—Use Master Mode
Undefined—Use Master Mode
I/F Width
8
8
Multiplex Philips
Data9
Data8
Data7
Data6
Data5
Data4
Data3
Data2
Format
Number
0x0
0x2
REV. 0