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CN8474AEPF 参数 Datasheet PDF下载

CN8474AEPF图片预览
型号: CN8474AEPF
PDF下载: 下载PDF文件 查看货源
内容描述: 多通道同步通信控制器( MUSYCC ™ ) [Multichannel Synchronous Communications Controller (MUSYCC?)]
分类和应用: 通信控制器
文件页数/大小: 221 页 / 2104 K
品牌: CONEXANT [ CONEXANT SYSTEMS, INC ]
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6.0 Basic Operation  
CN8478/CN8474A/CN8472A/CN8471A  
6.3 Channel Operation  
Multichannel Synchronous Communications Controller (MUSYCC™)  
6.3.18 Channel Jump  
A channel jump request is issued by the host via a service request. For a receiver,  
channel jumps are the same as channel activation.  
For a transmitter, channel jumps are non-destructive to currently serviced  
messages. The channel state is not reset as in the channel activate sequence.  
Therefore, a transmitter channel must be activated first, then subsequent jump  
requests can be made using the channel jump service request. For a transmitter,  
channel jumps provide a non-destructive way to start transmitting a new message  
list. MUSYCC waits until the completion of the current message before jumping  
to a message list pointed to by a new Head Pointer.  
A jump request is issued by the host via a service request towards a channel in  
a channel group in MUSYCC.  
NOTE: The service request acknowledge (via the SACK Interrupt Descriptor) for  
the jump service request—specifically for the transmit direction—will not  
be output towards the host until after the current message is transmitted.  
For applications with long messages to transmit, the jump service request  
must be used with care.  
6.3.19 Frame Alignment  
Each serial port frame consists of a fixed number of bits grouped into time  
slots according to the frame alignment supplied by the serial port TSYNC and  
RSYNC signals. MUSYCC must be provided at least one external  
synchronization pulse on the TSYNC and RSYNC input pins after the respective  
channel group is enabled. After this initial sync pulse, MUSYCC tracks  
subsequent serial port frame boundaries using its internal flywheel mechanism or  
the next applied sync pulse.  
NOTE: Nx64 serial port mode does not operate the internal flywheel and therefore  
requires periodic TSYNC and RSYNC pulses to keep track of serial port  
frame boundaries.  
In addition to tracking serial port frame boundaries, the internal flywheel  
generates a frame synchronization signal that can be selected to control the  
channel group's alignment of Transparent mode channel data streams. By default,  
the frame synchronization signal from the internal flywheel determines  
Transparent mode channel data stream alignment. If external data stream  
synchronization is preferred, the SFALIGN bit field in the Group Configuration  
Descriptor can be set to expect this synchronization signal to come from the serial  
port TSYNC and RSYNC input pins. While SFALIGN is set, the internal  
flywheel continues to operate, but the synchronization signal from the flywheel is  
not used to determine data stream alignment. Instead, alignment is provided by  
the external framer device which is allowed to strobe the sync input pins at  
periodic frame intervals or at any desired multiple of the frame interval  
(i.e., superframe).  
Each serial port frame carries stream data from one or more packetized HDLC  
or unpacketized Transparent mode channels. Although channels are mapped to  
specific time slots within the serial port frame, each channel's data streaming  
process may or may not have a particular alignment with respect to that channel's  
assigned time slot boundaries, depending upon whether the channel is configured  
to operate in HDLC or Transparent mode.  
6-24  
Conexant  
100660E  
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