cx25870 Conexant Systems, Inc., cx25870 Datasheet - Page 36

• Manufacturer Part Number: cx25870
• Description: Video Encoder With Adaptive Flicker Filtering And Hdtv Output
• Manufacturer: Conexant Systems, Inc.

1.0 Functional Description
1.3 Device Description
Figure 1-7. Operating the CX25870/871 in Slave Interface
1-20
1.3.7.4 Slave Interface
Controller
Graphics
In slave interface, no output signals are generated by the encoder. The
CX25870/871 relies strictly on the graphics controller to send clock and timing
signals to trigger when a new clock period, new line, and new frame starts.
Because no frequency reference signal is used (CLKO), the master device must
pre-program the encoder with an appropriate register set so the CX25870/871
expects data at the specific digital pixel rate prior to actually receiving the data. In
addition, the timing signals must be shaped so they adhere to the appropriate slave
interface timing diagrams illustrated in
of this interface, Conexant recommends its use only as a final option.
controller as the master device and S-Video and 2 Composite ports as the video
outputs.
required for this configuration. The amount of inputs will increase to 15 (without
BLANK*) or 16 (with BLANK*) if 24-bit multiplexed RGB mode is chosen as
the Input Pixel Mode (i.e., IN_MODE[3:0] = 0000) by the designer.
interface to ensure that the input and output video streams remain synchronized.
If either the master device, supplying the HSYNC* and VSYNC* inputs, or the
encoder, which receives the data, is not correctly programmed, the output image
will lose lock with the input. By running the CX25870/871 in either clock master
interface, any timing errors that occur can be absorbed to some extent by the
expansive on-board FIFO.
The slave interface is illustrated in
A minimum of 11 inputs (CLKI, HSYNC*, VSYNC*, and P[7:0]) are
It is highly recommended that the device operate in master or pseudo-master
HSYNC*
VSYNC*
BLANK*
RGB or
YCrCb
Clock
Conexant
Flicker-Free Video Encoder with Ultrascale Technology
CLKI
Cx25870/
CX25871
Figure 1-7
Chapter
4.0. Due to the added complexity
below using the graphics
Composite #1
Luma
Chroma
Composite #2
CX25870/871
100381B
100381_056