
XRT7245
DS3 UNI FOR ATM
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PRELIMINARY
REV. 1.03
XII
Differences Between the M13 and C-Bit Parity Frame Formats ..............................................................189
Definition of the DS3 Frame Overhead Bits ...............................................................................................190
P-Bits (Applies to M13 and C-Bit Parity Frame Formats) .........................................................................190
Alarm Indication Signal (AIS) Detection (C-Bit Parity Framing Format only) .........................................190
IDLE Condition Signal .................................................................................................................................190
FEAC (Only available for the C-bit Parity Frame Format) ........................................................................191
FEBE (Only available for the C-bit Parity Frame Format) .........................................................................191
Transmit Yellow Alarm (X-bits) ...................................................................................................................191
UDL: User Data Link (C-bit Parity Frame Format Only) ............................................................................191
DL: Path Maintenance Data Link (C-bit Parity Frame Format Only) ........................................................191
Tx DS3 M-Bit Mask Register, Address = 17h .............................................................................................192
Bit 3—Tx Err (Transmit Errored) P-Bit .......................................................................................................192
Bits 2—0: M-Bit Mask[2:0] ...........................................................................................................................192
F-Bit Error Insertion ........................................................................................................................................192
Tx DS3 F-Bit Mask1 Register, Address = 18h ............................................................................................192
Tx DS3 F-Bit Mask2 Register, Address = 19h ............................................................................................192
Tx DS3 F-Bit Mask3 Register, Address = 1Ah ...........................................................................................193
Tx DS3 F-Bit Mask4 Register, Address = 1Bh ...........................................................................................193
Operating the Transmit FEAC Processor ......................................................................................................193
Writing in the FEAC Codeword ......................................................................................................................193
Tx DS3 FEAC Register—Address: 1Dh ......................................................................................................193
Enabling the Transmit FEAC Processor ........................................................................................................193
Transmit DS3 FEAC Configuration and Status Register—Address: 1Ch ...............................................194
Initiate the Transmission of the FEAC Message ............................................................................................194
Transmit DS3 FEAC Configuration and Status Register—Address: 1Ch ...............................................194
Flag Sequence Byte .....................................................................................................................................196
SAPI—Service Access Point Identifier ......................................................................................................196
TEI—Terminal Endpoint Identifier ..............................................................................................................196
Control ..........................................................................................................................................................196
Information Payload ....................................................................................................................................196
Frame Check Sequence Bytes ....................................................................................................................196
Operation of the LAPD Transmitter ............................................................................................................196
Specifying the Type of LAPD Message ......................................................................................................197
Transmit DS3 LAPD Configuration Register (Address = 1Eh) .................................................................197
Enabling the LAPD Transmitter ..................................................................................................................197
Transmit DS3 LAPD Configuration Register (Address = 1Eh) .................................................................197
Bit 0—TxLAPD Enable .................................................................................................................................197
Initiate the Transmission ................................................................................................................................198
Tx DS3 LAPD Status/Interrupt Register (Address = 1Fh) .........................................................................198
The Mechanics of Transmitting a New LAPD Message .................................................................................199
Address = 01h, UNI I/O Control Register ...................................................................................................199
Address = 04h, UNI Interrupt Enable Register ..........................................................................................200
Tx DS3 M-Bit Mask Register, Address = 17h .............................................................................................200
Bit 4—FEBE Register Enable ......................................................................................................................200