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XRT79L71
PRELIMINARY
11
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
To accept user payload data, in a byte-wide manner (via an 8-bit wide Input Data Bus)
To (while accepting this user payload data, via this byte-wide interface, encapsulate this user data into an
HDLC frame)
To generate and transmit a repeating string of Flag Sequence octets (0x7E), whenever the Transmit High-
Speed HDLC Controller block is not accepting nor processing user data
To route these outbound HDLC frames and Flag Sequence octets to the Transmit DS3/E3 Framer block for
further processing.
NOTES:
1.
Whenever the XRT79L71 has been configured to operate in the High-Speed HDLC Controller Mode, then the role
of the Transmit Payload Data Input Interface block will be replaced by the Transmit High-Speed HDLC Controller
block.
2.
The Transmit High Speed HDLC Controller block should NOT be confused with the Transmit LAPD Controller
block (which also exists within the XRT79L71).
1.2.2
The Transmit Overhead Data Input Interface block (not shown in Figure 3) If the XRT79L71 has been configured to operate in the High-Speed HDLC Controller Mode, then the Transmit
Overhead Data Input Interface block will be disabled.
1.2.3
The Transmit LAPD Controller Block
The purpose of the Transmit LAPD Controller block is to permit the user to transmit LAPD/PMDL (Path
Maintenance Data Link) Messages to the remote terminal equipment. The Transmit LAPD Controller block
comes with a LAPD Controller/Transmitter (not to be confused with the Transmit High-Speed HDLC Controller)
and 90 bytes of on-chip RAM (for storage of outbound PMDL Messages) prior to transmission.
1.2.4
The Transmit FEAC Controller Block (DS3 Applications only)
The purpose of the Transmit FEAC Controller block is to permit the user to transmit FEAC (Far-End Alarm &
Control) Messages to the remote terminal equipment.
NOTE: The Transmit FEAC Controller block is only active if the XRT79L71 is configured to operate in the DS3, C-bit Parity
Framing format.
1.2.5
The Transmit Trail-Trace Message Controller Block (E3, ITU-T G.832 Applications only)
The purpose of the Transmit Trail-Trace Message Controller block is to permit a given terminal equipment to
repeatedly transmit a "Trail-Trace" Message to the remote terminal equipment, via the TR bytes, within each
outbound E3, ITU-T G.832 frame.
1.2.6
The Transmit SSM Controller Block (E3, ITU-T G.832 Applications only)
The purpose of the Transmit SSM Controller Block is to permit a given terminal equipment to repeatedly
transmit the "Synchronization Status Message" to the remote terminal equipment, via the MA byte, within each
outbound E3, ITU-T G.832 frame.
1.2.7
The Transmit DS3/E3 Framer Block
The purpose of the Transmit DS3/E3 Framer block is to accept payload data from the Transmit High-Speed
HDLC Controller block, the Transmit LAPD Controller block and the Transmit FEAC Controller block and to
construct a DS3/E3 data-stream for transmission to the remote terminal equipment. More specifically, in this
particular application, the Transmit DS3/E3 Framer block is responsible for accepting the outbound HDLC
frames and Flag Sequences octets from the Transmit High-Speed HDLC Controller block, and inserting this
data into the payload bits/bytes within the outbound DS3/E3 fames. Additionally, the Transmit DS3/E3 Framer
block can be configured to do all of the following.
To transmit the AIS Indicator (upon Software Control)
To automatically transmit the FERF/RDI Indicator (in response to the Receive DS3/E3 Framer block
declaring the LOS, LOF/OOF or AIS defect condition)