Set-Top Box Solutions
The CX24430/1 and CX24432/3 cable modem sub-systems include
a complete upstream/downstream physical layer, and an Ethernet
MAC in addition to the cable modem MAC and host processor.
The set-top box decoder functionality includes an MPEG-2 video
decoder, digital audio decoder, three multi-standard transport
streamdemultiplexers, an advanced 2D graphics processor,
TV encoder, multi-plane compositing engine, a 256 QAM
demodulator/FEC block and a high performance 32-bit ARM920
RISC processor with integrated peripheral I/O ports. This makes
for an architecture that delivers a rich, high quality navigation/
user interface for advanced electronic program guides and other
interactive TV applications.
The dual CPU system architecture provides 500+ aggregate MIPS
for hosting the operating system, interactive middleware, DOCSIS
stack and interactive TV applications, while delivering industry-
leading cable modem packet performance. The CX24430/1 and
CX24432/3 ICs fully support Data Over Cable Service Interface
Specification (DOCSIS®) and EuroDOCSIS™ version 1.1 standards.
The CX24430 and CX24431 set-top box sub-systems also enable
advanced Personal Video Recorder (PVR) functionality. Users are able
to record two different programs simultaneously with DES copy
protection while playing back a third. The CX24430 and CX24431
incorporate a built-in high-speed hard disk drive controller interface
for fast data transfers in PVR applications like pause, instant replay,
fast forward and rewind.
Analog video support is provided by four high quality CVBS/
S-video/RGB output signals for all worldwide NTSC/PAL/SECAM
broadcast standards. The IC also provides an input port for
digitized analog signals based on the CCIR 656 format to support
analog TV display and compositing with program guide graphics.
The CX24430/1 and CX24432/3 ICs integrate dual, high
performance SDRAM memory controllers. A 32-bit 143MHz
memory controller supports all of the set-top box back-end
requirements in a unified memory architecture. This back-end
SDRAM memory system is used to support the requirements
of the main system CPU, MPEG-2 Audio Video (A/V) decoder,
transport demultiplexer, graphics, frame buffer and the still plane
picture buffers. A second, dedicated 16-bit 143MHz SDRAM
controller services the needs of the cable modem system, including
the code store for the RTOS executing on the cable modem
CPU as well as packet buffers for bridging to Ethernet and USB.
TS I/O Switch
Annex A, B, C
• MPEG Scale
• Still Plane
• Flicker Filter
CX24430/1 IC Block Diagram