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参数资料
| 型号： | CDB4955A |
| 厂商： | Cirrus Logic Inc |
| 文件页数： | 18/60页 |
| 文件大小： | 0K |
| 描述： | EVALUATION BOARD FOR CS4955A |
| 标准包装： | 1 |
| 主要目的： | 视频，视频处理 |
| 嵌入式： | 是，其它 |
| 已用 IC / 零件： | CS4955 |
| 主要属性： | NTSC/PAL 数字视频编码器 |
| 次要属性： | 图形用户界面，RS-232 接口 |
| 已供物品： | 板 |
| 相关产品： | CS4954-CQZR-ND - IC VID ENCODER NTSC/PAL 48-TQFP 598-1682-ND - IC VIDEO ENCODER NTSC/PAL 48TQFP |
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CS4954 CS4955
DS278F6
25
TTXRQ provides a fully programmable request
signal to the teletext source, indicating the insertion
period of the bitstream at independently selectable
lines for both TV fields. The internal insertion win-
dow for text is set to either 360, 296 or 288 teletext
bits, depending on the selected teletext standard.
The clock run-in is included in this window.
Teletext in enabled by setting the TTX_EN bit to
“1”. The TTX_WST bit in conjunction with the
TV_FORMAT register selects one of the 4 teletext
encoding possibilities.
The teletext timing is shown in the Figure 12.
TTXHS and TTXHD are user programmable and
therefore allow the user to have full control over
when teletext data is sent to this device.
The time tFD is the time needed to interpolate tele-
text input data and insert it into the CVBS and Y
output signals, such that it appears between
tTTX = 9.8 μs and tTTX =12 μs after the leading
edge of the horizontal synchronization pulse. tFD
changes with the TV standard and the selected
teletext standard. Please refer to ITU-R BT.653-2
for more detailed information.
The time tPD is the pipeline delay time introduced
by the source that is gated by TTXRQ in order to
deliver teletext data. This delay is programmable
through the register TTXHD. For every active
HIGH transition at output pin TTXRQ, a new tele-
text bit must be provided by the source. The time
between the beginning of the first TTXRQ pulse
and the leading edge of H-sync is programmable
through the TTXHS register.
Since the beginning of the pulses representing the
TTXRQ signal and the delay between the rising
edge of TTXRQ and valid teletext input data are
fully programmable, the TTXDAT data is always
inserted at the correct position after the leading
edge of the outgoing horizontal synchronization
pulse.
The time tTTXWin is the internally used insertion
window for TTX data; it has a constant length
depending on the selected teletext standard which
allows insertion of 360 TTX bits (6.9375
Mbit/sec) (European teletext) or 296 TTX bits
(5.6427875 Mbit/sec) (WST PAL) or 288 TTX bits
(5.727272 Mbit/sec) (NABTS) or 296 TTX bits
(5.727272 Mbit/sec) (WST NTSC) respectively.
Using the appropriate programming, all suitable
lines of the odd field (TTXOVS through TTX-
OVE) plus all suitable lines of the even field
(TTXEVS through TTXEVE) can be used for tele-
text insertion. In addition it is possible to selec-
tively disable the teletext insertion on single lines.
This can be programmed by setting the
TTX_LINE_DIS1,
TTX_LINE_DIS2
and
TTX_LINE_DIS3 registers appropriately.
Note that the TTXDAT signal must be synchro-
nized with the 27 MHz clock. The pulse width of
the TTXRQ signal varies between three and four
27 MHz clock cycles. The variation is necessary in
Figure 12. Teletext Timing (Pulsation Mode)
Figure 13. Teletext Timing (Window Mode)
CVBS/Y
TTXRQ
TTXDAT
textbit #: 1
2
3
4
5
tTTX
tTTXWin
tPD
tFD
CVBS/Y
TTXRQ
TTXDAT
textbit #: 1
2345
tTTX
tTTXWin
tPD
tFD
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相关代理商/技术参数 |
参数描述 |
|---|---|
| CDB-496122-EV2 | 制造商:Cirrus Logic 功能描述: |
| CDB496122-EV2 | 功能描述:音频 IC 开发工具 Eval Bd CobraNet Trnspt/AdNtwrk Prcsr RoHS:否 制造商:Texas Instruments 产品:Evaluation Kits 类型:Audio Amplifiers 工具用于评估:TAS5614L 工作电源电压:12 V to 38 V |
| CDB49X | 制造商:Cirrus Logic 功能描述:EVAL BD - BASE BOARD FOR AUDIO DSP - Boxed Product (Development Kits) |
| CDB-5 | 功能描述:电线导管 5’ Brown RoHS:否 制造商:Panduit 类型:Slotted SideWall Open finger design wiring cut 材料:Polypropylene 颜色:Light Gray 大小: 最大光束直径: 抗拉强度: 外部导管宽度:25 mm 外部导管高度:25 mm |
| CDB5012 | 制造商:CIRRUS 制造商全称:Cirrus Logic 功能描述:Evaluation Board |
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