Pixclk
VSYNC
HSYNC
Internal Modules
146
SPRUHI7A – December 2012 – Revised June 2016
Copyright © 2012–2016, Texas Instruments Incorporated
High-Definition Video Processing Subsystem (HDVPSS)
The configuration for each device input port is described in
Table 1-53. Valid Input Port Configurations
Port A
Port B
8 Bit
Off
16 Bit
Off
24 Bit
Off
8 Bit
8 Bit
16 Bit
8 Bit
Off
8 Bit
Each Port can individually be configured as Discrete Sync or Embedded Sync.
1.2.8.2.5.1 Signal Relationships
A digital representation of video can be realized by using HSYNC and VSYNC signals to identify frame
start and line start. Suppose HSYNC and VSYNC are active high,
shows the general
relationship of these signals.
Figure 1-90. Discrete Sync Signals
Every Pixclk cycle carries either an active pixel or a blanking pixel. VSYNC pulses between two fields (or
frames, in the case of progressive video). HSYNC pulses to signify the beginning of every line. An
ACTVID signal can be used as a data valid to specify active video.
Discrete Sync cannot be used with any multi-camera multiplexed stream inputs. In the device, if Port A is
configured for 24 bit discrete sync, then Port B must be disabled since there are no more data input pins
left over for Port B.
If Port A is not 24 bits, then the 8-bit Port B can be configured and enabled for either discrete or
embedded sync.
Discrete sync basic mode is used to determine the type of vertical blanking signal.
DISCRETE_BASIC_MODE=’0’ means that the vertical blanking interval is specified by the signaling. In the
cases where there is no awareness of vertical blanking start and end, vertical blanking data is saved in the
Active Video Buffer (DISCRETE_BASIC_MODE=’1’).
1.2.8.2.5.2 General 5 Pin Interfaces
Discrete Sync signal handling varies among different sending devices. The information that must be
conveyed includes the pixel data value, field ID, horizontal blanking, and vertical blanking. Many devices
can be configured to adjust the timing of the signals relative to each other.
In this section, DATA will be depicted as 8 bits. However, discrete sync does optionally support 16b and
24b data input. Type 1 is named after a generic five pin interface between the sending and receiving
devices.
In
, P0 represents the first pixel in the horizontal blanking interval following the last vertical
blanking line of the previous field or frame. HSYNC specifies the horizontal blanking region and VSYNC
specifies that the P0 pixel is in the vertical sync area. HSYNC can be a strobe that is active one or more
cycles and can deassert before the actual end of horizontal blanking or HSYNC may be active for the full
duration of horizontal blanking.
Likewise, VSYNC can be a strobe that is active one or more cycles and can deassert before the actual
end of vertical blanking or VSYNC may be active for the full duration of vertical blanking.