1.0 Functional Description
CX25870/871
1.3 Device Description
Flicker-Free Video Encoder with Ultrascale Technology
The RGB primary color signals generated in SCART mode will not contain
any embedded syncs. For each output, the difference between the peak value
(pure white) and blanking level is 0.7 V ( 3 dB). Therefore, the blanking level
will reside at GND (0 mV) and the maximum level is 700 mV for RGB. The
HSYNC* and VSYNC* digital inputs received by the CX25870/871 continue to
act as a trigger to start a new line and new frame respectively as is the case with
Composite and SVHS outputs. The RGB signals are blanked in accordance with
the values contained in the H_BLANKO and V_BLANKO registers, with
H_CLKO and H_ACTIVE playing a lesser role.
The primary color signals expect a 75 Ω load from the display device. Correct
RGB amplitudes are generated when the CX25870’s SCART outputs each ‘see’
an equivalent impedance of 37.5 Ω between the source and destination.
By default, the RGB positive-going signals are transmitted from the CX25870
in the following manner:
Table 1-25. Default SCART Outgoing Signal Assignments
Pin # on CX25870/871
68 = DACA
SCART Output
Video[0] = Red Primary Color
70 = DACB
72 = DACC
66 = DACD
Video[1] = Green Primary Color
Video[2] = Blue Primary Color
Video[3] = PAL-BDGHI Composite
NOTE: Video[0-3] can be routed out of any of the 4 on-chip DACs by adjusting
the appropriate OUT_MUXA/B/C/D[1:0] bits.
Other major characteristics of the CX25870/871 SCART Output Mode are:
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•
Acceptable digital RGB inputs include 24/16/or 15 bits per pixel
multiplexed or nonmultiplexed, noninterlaced RGB.
Acceptable digital YCrCb inputs include 24/16 bits per pixel multiplexed
or nonmultiplexed, noninterlaced YCrCb.
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•
CX25870 can operate in master, pseudo-master, or slave interface.
Pixel sampling rate in this mode is determined based on the incoming and
outgoing clock frequencies (CLKI and CLKO).
•
•
DAC resolution for all DACs = 10-bits.
Red/Green/Blue/Composite SCART Output from CX25870/871 limited to
a max active resolution of 800 x 600.
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•
Y/C SCART output OK to a maximum active resolution of 1024 x 768.
Compliance with the European EN50-049 SCART connector standard.
Blue should be received as Pin #7, Green as Pin #11, Red as Pin #15, and
CVBS Out from the CX25870 as Composite Out at Pin #19 (Display Side
of Connector).
•
Compliance with the CEI IEC Publication 933-1 standard. Blue should be
received as Pin #7, Green as Pin #11, Red as Pin #15, and CVBS Out from
the CX25870 as Composite Out at Pin #19 (Display Side of Connector).
The CX25870 is compliant with the major standards and technical reports
governing the SCART interface. Table 1-26 summarizes the pins to be used for
transmission of SCART RGB/CVBS video with this Conexant device.
1-78
Conexant
100381B
CONEXANT [ CONEXANT SYSTEMS, INC ]
