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CS7808-CM Datasheet(PDF) 21 Page - Cirrus Logic |
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CS7808-CM Datasheet(HTML) 21 Page - Cirrus Logic |
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21 CS7808 rupts can be generated on specific or generic events. Infrared inputs can be filtered to make them free of glitches or stored unfiltered into memory. Control of all the internal clocks is also possible. Internal PLLs are used to generate the internal sys- tem and memory clocks and audio clocks of any widely used frequency. 3.8 Host Interface The CS7808 has a programmable interface port which can be configured to connect to industry- standard ATAPI interfaces without external glue logic. The Host interface can be set up in ATAPI mode, to connect directly to any ATAPI hard-disk drive (using two chip selects). 3.9 MPEG Video Decoding Compressed MPEG data is read from Internet through Ethernet controller(Host I/F) or soft mo- dem(CODEC I/F) into an input FIFO in DRAM. The data flow (DMA) controller moves Video packets from the input FIFO into the MPEG decod- er’s input FIFO (also in DRAM). The DMA con- troller can also perform advanced functions such as start code search, relieving the RISC processors. The System Synchronization function is used to control the timing of MPEG picture decoding. The MPEG Video decoder processes I, B, and P frames, and writes to video frame buffers in DRAM for output to the display. Special anti-tearing logic en- sures that currently displayed frame buffers are not overwritten. 3.10 Audio Processing Compressed Audio data is decompressed, then written to a PCM output FIFO, also in DRAM The DMA and decompression stages of audio process- ing can be done with a combination of the DMA unit, DSP, and RISC processors. The DSP is opti- mized for audio processing, so most common for- mats can be handled by the DSP alone, including AC-3, DTS, MPEG2 audio, and MP3. The DSP has enough reserve bandwidth to handle the Karaoke echo-mix and pitch shift, and AC-3 down-mix functions. The audio output data is written into a DRAM FIFO in 16-, 18-, 20- or 24-bit PCM format. A flex- ible audio output stage can simultaneously output 8 channels of PCM data to audio DACs, or 6 chan- nels of audio data plus an IEC-958 encoded output, at up to 96 KHz. The audio interface also includes a flexible PCM input interface, which can input a wide range of protocols from an audio ADC or an IEC-958 receiver. 3.11 Soft Modem The soft modem processing is handled by one of the RISC processors, which is typically dedicated for that function. Data rates up to 56 Kbits (V.90 protocol) are supported. The CS7808 interfaces to a simple external CODEC/DAA circuit using a flexible serial interface. The serial interface is a ful- ly programmable, bi-directional interface and can be used either as a PCM interface or as an AC97 in- terface. In PCM mode, the sample size could be ad- justed to 20, 18 or 16 bits to match common DAC and ADC formats, or any other specific size. In AC97 mode, any slot can be used to interface either a modem CODEC or an audio CODEC. 3.12 Video The Digital Video Interface provides flexible and powerful means of outputting digital video data to external devices in CCIR601/3 and CCIR656 for- mats. The interface directly supports NTSC/PAL video encoding, in both master and slave synchro- nization configurations. The internal frame buffer format could be 4:2:0, 4:2:2, YUV655, RGB565 and RGB555. Cirrus Logic provides some easy-to- use utilities in order to get the best advantage of the powerful video filtering capabilities of the CS7808. The CS7808 also features an NTSC/PAL video de- coder input interface. The interface accepts CCIR601, CIF, and QCIF formats, out of many TV decoders on the market. The video processor also |
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