CN8478/CN8474A/CN8472A/CN8471A
6.0 Basic Operation
Multichannel Synchronous Communications Controller (MUSYCC™)
6.4 Protocol Support
6.4.4 Zero-Bit Insertion/Deletion
MUSYCC provides 0-bit insertion and deletion when it encounters five
consecutive 1s within a frame. In the receiver, a 0 bit is de-inserted, and in the
transmitter a 0 bit is inserted after five 1s are seen.
6.4.5 Message Configuration Bits
A group of bits specified in a Transmit Buffer Descriptor specifies the data to be
transmitted at the transmit channel after the end of a current message has been
transmitted. The bits are collectively known as the Message Configuration
Descriptor and include the specifications for the following:
•
•
•
•
Idle Code specification, IC
Inter-message Pad Fill Enable, PADEN
Inter-message Pad Fill Count, PADCNT
Repeat Message Transmission, REPEAT
6.4.5.1 Idle Code
The Idle Code (IC) specification allows an idle code to be transmitted after the
current message in case the next message is not available to be transmitted or
inter-message pad fill is requested via PADEN.
6.4.5.2 Inter-message
Pad Fill
The Pad Enable (PADEN) and Pad Count (PADCNT) specifications allow pad fill
octets (a sequence of one or more specified idle codes) to be transmitted between
messages. PADEN enables or disables the pad fill octet transmission feature.
PADCNT is the minimum number of fill octets to be transmitted between the
closing flag of one message and the opening flag of the next message.
6.4.5.3 Repeat Message
Transmission
The Repeat Message Transmission (REPEAT) specification allows a single
message to be transmitted repeatedly without additional host intervention. This
feature is required to support SS7 message retransmission. In the SS7 application,
a retransmitted message is usually 3, 4, or 5 octets in length. Message
retransmission in MUSYCC requires that the entire message be held in a single
shared memory message buffer, versus being spread across multiple buffers. The
message retransmission feature is not limited to SS7 applications.
6.4.6 Message Configuration Bits Copy Enable/Disable
The message configuration bits described above are used in special data
communication applications requiring the following attributes specified on a
per-message basis:
•
•
•
Specific idle code is to be transmitted between messages.
Inter-message pad fill is required.
Repeat message transmission is required.
If at least one transmit channel in a channel group is supporting an application
which requires any one of the above attributes, the Message Configuration Bits
Copy must be enabled for the entire channel group by setting the MCENBL
bit field to 1.
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