XRT72L56 Datasheet, PDF (17/486 Pages) Exar Corporation – SIX CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

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PRELIMINARY
XRT72L56
SIX CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. P1.1.2
terface block of the XRT72L56 for Mode 2 (Serial/Local-Timed/Frame-Slave) Operation .................. 360
Figure 160. Behavior of the Terminal Interface signals between the XRT72L56 and the Terminal Equipment
(Mode 2 Operation) ............................................................................................................................. 361
FRAMER OPERATING MODE REGISTER (ADDRESS = 0X00) ..................................................................... 361
Figure 161. Illustration of the Terminal Equipment being interfaced to the Transmit Payload Data Input In-
terface block of the XRT72L56 for Mode 3 (Serial/Local-Timed/Frame-Master) Operation ................ 362
Figure 162. Behavior of the Terminal Interface signals between the XRT72L56 and the Terminal Equipment
(E3 Mode 3 Operation) ........................................................................................................................ 363
FRAMER OPERATING MODE REGISTER (ADDRESS = 0X00) ..................................................................... 363
Figure 163. Illustration of the Terminal Equipment being interfaced to the Transmit Payload Data Input In-
terface block of the XRT72L56 for Mode 4 (Nibble-Parallel/Loop-Timed) Operation .......................... 364
Figure 164. Behavior of the Terminal Interface signals between the XRT72L56 and the Terminal Equipment
(Mode 4 Operation) ............................................................................................................................. 365
FRAMER OPERATING MODE REGISTER (ADDRESS = 0X00) ..................................................................... 366
Figure 165. Illustration of the Terminal Equipment being interfaced to the Transmit Payload Data Input In-
terface block of the XRT72L56 for Mode 5 (Nibble-Parallel/Local-Time/Frame-Slave) Operation ..... 367
Figure 166. Behavior of the Terminal Interface signals between the XRT72L56 and the Terminal Equipment
(E3 Mode 5 Operation) ........................................................................................................................ 368
FRAMER OPERATING MODE REGISTER (ADDRESS = 0X00) ..................................................................... 368
Figure 167. Illustration of the Terminal Equipment being interfaced to the Transmit Payload Data Input In-
terface block of the XRT72L56 for Mode 6 Operation ......................................................................... 369
Figure 168. Behavior of the Terminal Interface signals between the XRT72L56 and the Terminal Equipment
(E3 Mode 6 Operation) ........................................................................................................................ 370
FRAMER OPERATING MODE REGISTER (ADDRESS = 0X00) ..................................................................... 370
6.2.2 The Transmit Overhead Data Input Interface ........................................................................................ 370
Figure 169. Simple Illustration of the Transmit Overhead Data Input Interface block ........................ 371
TABLE 72: A LISTING OF THE OVERHEAD BITS WITHIN THE E3 FRAME, AND THEIR POTENTIAL SOURCES, WITHIN
THE XRT72L56 IC ................................................................................................................................ 372
TABLE 73: DESCRIPTION OF METHOD 1 TRANSMIT OVERHEAD INPUT INTERFACE SIGNALS ..................... 374
Figure 170. Illustration of the Terminal Equipment being interfaced to the Transmit Overhead Data Input
Interface (Method 1) ............................................................................................................................ 375
TABLE 74: THE RELATIONSHIP BETWEEN THE NUMBER OF RISING CLOCK EDGES IN TXOHCLK, (SINCE "TXO-
HFRAME" WAS LAST SAMPLED "HIGH") TO THE E3 OVERHEAD BIT, THAT IS BEING PROCESSED ................ 376
Figure 171. Illustration of the signal that must occur between the Terminal Equipment and the XRT72L56,
in order to configure the XRT72L56 to transmit a Yellow Alarm to the remote terminal equipment ... 378
TABLE 75: DESCRIPTION OF METHOD 1 TRANSMIT OVERHEAD INPUT INTERFACE SIGNALS ..................... 379
Figure 172. Illustration of the Terminal Equipment being interfaced to the Transmit Overhead Data Input
Interface (Method 2) ............................................................................................................................ 380
TABLE 76: THE RELATIONSHIP BETWEEN THE NUMBER OF TXOHENABLE PULSES (SINCE THE LAST OCCURRENCE
OF THE TXOHFRAME PULSE) TO THE E3 OVERHEAD BIT, THAT IS BEING PROCESSED BY THE XRT72L56 381
Figure 173. Behavior of Transmit Overhead Data Input Interface signals between the XRT72L56 and the
Terminal Equipment (for Method 2) .................................................................................................... 383
6.2.3 The Transmit E3 HDLC Controller ........................................................................................................ 383
Figure 174. LAPD Message Frame Format ....................................................................................... 384
TABLE 77: THE LAPD MESSAGE TYPE AND THE CORRESPONDING VALUE OF THE FIRST BYTE, WITHIN THE INFOR-
MATION PAYLOAD .................................................................................................................................. 384
TRANSMIT E3 LAPD CONFIGURATION REGISTER (ADDRESS = 0X33) ..................................................... 385
TABLE 78: RELATIONSHIP BETWEEN TXLAPD MSG LENGTH AND THE LAPD MESSAGE SIZE .................. 385
TXE3 CONFIGURATION REGISTER (ADDRESS = 0X30) ............................................................................ 386
TXE3 LAPD CONFIGURATION REGISTER (ADDRESS = 0X33) ................................................................. 386
TRANSMIT E3 LAPD CONFIGURATION REGISTER (ADDRESS = 0X33) ..................................................... 386
TXE3 LAPD STATUS AND INTERRUPT REGISTER (ADDRESS = 0X34) ...................................................... 387
TXE3 LAPD STATUS AND INTERRUPT REGISTER (ADDRESS = 0X34) ...................................................... 388
Figure 175. Flow Chart depicting how to use the LAPD Transmitter (LAPD Transmitter is configured to re-
transmit the LAPD Message frame repeatedly at One-Second intervals) ........................................... 389
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