CS4954-CQ View Datasheet(PDF) - Cirrus Logic
Part Name
Description
Manufacturer
CS4954-CQ Datasheet PDF : 56 Pages
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CS4954 CS4955
Note that the teletext databits are shaped according
to the ITU R.BT653-2 specifications.
If register 0×31 bit 3 is set, (TTX_WINDOW=1)
the teletext is in windows mode, the request pulses
become a window where the bit provided on the
TTXDAT pin are valid (see Figure 13).
Alternately to the pulsation mode (where the num-
ber of request pulses are determined by the teletext
standard chosen), the length of the window must be
programmed by the user independently of the tele-
text standard used. The length of the window is
programmed through register 0×29 TTXHS (start
of window) and register 0×2A (TTXHD) and 0×31
(end of window). The end-of-window register is a
11 bit value.
In teletext window mode, the TTXHS value can be
selected using the values in Table 5. Although
these values may need to be adjusted to match your
system delay, use the following equation to com-
pute the TTXHD value:
TTXHS + 1402 = TTXHD (for Europe)
TTXHS + 1151 = TTXHD (for WST)
TTXHS + 1122 = TTXHD (for NABTS)
TV standard
NTSC-M
NTSC-M
PAL-B
PAL-B
PAL-M
PAL-M
PAL-N (non Arg.)
PAL-N (non Arg.)
PAL-N (Arg.)
PAL-N (Arg.)
Teletext
standard
NABTS
WST-NTSC
Europe TTX
WST-PAL
NABTS
WST-NTSC
Europe TTX
WST-PAL
Europe TTX
WST-PAL
TTXHS
(register
value) tTTX
161 10.5 µs
142 9.8 µs
204 12.0 µs
163 10.5 µs
161 10.5 µs
142 9.8 µs
204 12.0 µs
163 10.5 µs
204 12.0 µs
163 10.5 µs
Table 5. Teletext timing parameters
5.12. Color Bar Generator
The CS4954/5 is equipped with a color bar genera-
tor that is enabled through the CBAR bit of the
CONTROL_1 Register. The color bar generator
works in master or Slave Mode and has no effect on
the video input/output timing. If the CS4954/5 is
configured for Slave Mode color bars, proper video
timing must be present on the HSYNC and
VSYNC pins for the color bars to be displayed.
Given proper Slave Mode input timing or Master
Mode, the color bar generator will override the vid-
eo input pixel data.
The output of the color bar generator is instantiated
after the chroma interpolation filter and before the
luma delay line. The generated color bar numbers
are for 100% amplitude, 100% saturation NTSC
EIA color bars or 100% amplitude, 100% satura-
tion PAL EBU color bars. For PAL color bars, the
CS4954/5 generates NTSC color bar values, which
are very close to standard PAL values. The exact
luma and chroma values are listed in Table 6. .
Color
White
Yellow
Cyan
Green
Magenta
Red
Blue
Black
Cb
Cr
Y
0
0
+ 167
- 84
+ 14
+ 156
+ 28
- 84
+ 138
- 56
- 70
+ 127
+ 56
+ 70
+ 110
- 28
+ 84
+ 99
+ 84
- 14
+ 81
0
0
+ 70
Table 6. Internal Color Bar Values (8-bit values, Cb/Cr
are in twos complement format)
5.13. VBI encoding
VBI (Vertical Blanking Interval) encoding is per-
formed according to SMPTE RP 188 recommenda-
tions. In NTSC mode lines 10 - 20 and lines 272 -
283 are used for the transmission of ancillary data.
In PAL mode lines 6 - 22 and lines 318 -335 are
used. The VBI encoding mode can be set through
the CONTROL_3 register.
All digital input data is passed through the chip
when this mode is enabled. It is therefore the re-
sponsibility of the user to ensure appropriate ampli-
DS278PP4
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