28500-DSH-002-C_15 Datasheet, PDF (17/224 Pages) M/A-COM Technology Solutions, Inc. – Multichannel Synchronous Communications Controller

Introduction
1.1
CX28500’s Operational Modes
Table 1-1 explains the CX28500’s supported serial port mode.
Table 1-1. Supported Serial Port Modes
CX28500 Serial Port Modes
Description
Conventional Unchannelized⁽¹⁾
Conventional Channelized⁽¹⁾⁽²⁾
Conventional T1 mode⁽¹⁾
TSBUS⁽²⁾⁽³⁾
In this mode, Transmit Synchronization (TSYNC) and Receive Synchronization (RSYNC) are ignored. The
serial input/output data stream is a bit-stream without framing or alignment. The bit-stream belongs to a
single logical channel. The CX28500 conventional, unchannelized mode can operate up to 13 Mbps for all 32
serial ports. The first six ports can operate unchannelized T3/E3, HSSI, or STS-1/STM-1 bit-stream up to 52
Mbps per serial interface (for reference, see Section 1.2).
The serial bit-stream is treated as a frame of N time slots (where N is less than or equal to 4096, given that
other restrictions are met). The maximum bandwidth embedded into the PCM highway for the first six ports
is STS-1 rate (51.84 Mbps). The byte and frame synchronization performed is based on receive and transmit
sync pulse (RSYNC and TSYNC). (For a detailed description of these signals, see Chapter 5.0.)
The serial bit-stream is treated as a frame of N time slots (where N has the same meaning as in channelized
mode). If the serial port is configured in T1 mode then the port operates according to the T1 framing
definition (i.e., 24 time slots, where the first bit is the F-bit). The difference between channelized mode and
T1 mode is that in T1 mode, the F-bit of the T1 frame is masked off and is dropped on input, and is
generated for the output (for proper timing only—a T1 framer is needed to generate the correct F-bit).
The TSBUS serial interface bit-stream is treated as a frame of N time slots (where N is defined as greater
than or equal to 6, and the aggregate number of time slots across all ports in any direction does not exceed
the 4096 available time slots in each direction, receive or transmit) or variable bandwidth time slots called
Virtual Serial Ports (VSPs). Byte synchronization and frame synchronization is performed based on the
TSBUS sync pulse STB (i.e., bus strobe). Mixed T1/E1 paths in one T3, mixed VT1.5/VT2 paths mapped to
VTGs in one STS1, and mixed VC11/VC12 paths mapped to TUG2 in STM-1 are allowed using this serial port
configuration.
FOOTNOTE:
(1) _{A conventional serial port is defined as seven input/output signals as follows: Transmit Clock (TCLK), Transmit Synchronization (TSYNC),}
Transmit Data (TDAT), Receive Clock (RCLK), Receive Synchronization (RSYNC), Receive Data (RDAT), Receive Out-Of-Frame, or Clear
To Send (ROOF/ CTS). (For a detailed description of these signals, see Section 2.1.)
(2) _{Channelized mode refers to a data bit stream segmented into frames. Each frame consists of a series of 8-bit time slots. The frame}
synchronization is maintained in both the transmit and receive direction by using the Transmit Synchronization (TSYNC) and Receive
Synchronization (RSYNC) input signals.
(3) _{A Time Slot Bus (TSBUS) is defined as seven input/output signals as follows: Transmit Clock (TCLK), Transmit Stuff (TSTUFF), Transmit}
Data (TDAT), Strobe (STB), Receive Clock (RCLK), Receive Stuff (RSTUFF), Receive Data (RDAT). (For a detailed description of these
signals, see Chapter 5.0).
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