XRT74L74 Datasheet, PDF (9/498 Pages) Exar Corporation – 4 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER

PRELIMINARY
XRT74L74
4 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER
REV. P1.1.1
6.1 DESCRIPTION OF THE E3, ITU-T G.751 FRAMES AND ASSOCIATED OVERHEAD BITS .................... 295
FIGURE 104. THE E3, ITU-T G.751 FRAMING FORMAT. ...................................................................................................................... 295
6.1.1 DEFINITION OF THE OVERHEAD BITS.................................................................................................................. 295
6.2 THE TRANSMIT SECTION OF THE XRT74L74 (E3, ITU-T G.751 MODE OPERATION) .......................... 296
FIGURE 105. THE XRT74L74 TRANSMIT SECTION WHEN IT HAS BEEN CONFIGURED TO OPERATE IN THE E3 MODE............................... 296
6.2.1 THE TRANSMIT PAYLOAD DATA INPUT INTERFACE BLOCK ........................................................................... 296
FIGURE 106. THE TRANSMIT PAYLOAD DATA INPUT INTERFACE BLOCK................................................................................................ 297
TABLE 62: LISTING AND DESCRIPTION OF THE PINS ASSOCIATED WITH THE TRANSMIT PAYLOAD DATA INPUT INTERFACE ....................... 298
FIGURE 107. THE TERMINAL EQUIPMENT BEING INTERFACED TO THE TRANSMIT PAYLOAD DATA INPUT INTERFACE BLOCK OF THE XRT74L74
FOR MODE 1 (SERIAL/LOOP-TIMED) OPERATION .................................................................................................................. 300
TXE3 CONFIGURATION REGISTER (ADDRESS = 0X30) ................................................................................................ 301
FIGURE 108. BEHAVIOR OF THE TERMINAL INTERFACE SIGNALS BETWEEN THE XRT74L74 TRANSMIT PAYLOAD DATA INPUT INTERFACE BLOCK
AND THE TERMINAL EQUIPMENT (FOR MODE 1 OPERATION) ................................................................................................. 302
FRAMER OPERATING MODE REGISTER (ADDRESS = 0X00) ......................................................................................... 302
FIGURE 109. THE TERMINAL EQUIPMENT BEING INTERFACED TO THE TRANSMIT PAYLOAD DATA INPUT INTERFACE BLOCK OF THE XRT74L74
FOR MODE 2 (SERIAL/LOCAL-TIMED/FRAME-SLAVE) OPERATION .......................................................................................... 303
FIGURE 110. BEHAVIOR OF THE TERMINAL INTERFACE SIGNALS BETWEEN THE XRT74L74 AND THE TERMINAL EQUIPMENT (MODE 2 OPERATION)
304
FRAMER OPERATING MODE REGISTER (ADDRESS = 0X00) ......................................................................................... 304
FIGURE 111. THE TERMINAL EQUIPMENT BEING INTERFACED TO THE TRANSMIT PAYLOAD DATA INPUT INTERFACE BLOCK OF THE XRT74L74
FOR MODE 3 (SERIAL/LOCAL-TIME/FRAME-MASTER) OPERATION ......................................................................................... 305
FIGURE 112. BEHAVIOR OF THE TERMINAL INTERFACE SIGNALS BETWEEN THE XRT74L74 AND THE TERMINAL EQUIPMENT (E3 MODE 3 OPER-
ATION) ................................................................................................................................................................................ 306
FRAMER OPERATING MODE REGISTER (ADDRESS = 0X00) ......................................................................................... 306
FIGURE 113. THE TERMINAL EQUIPMENT BEING INTERFACED TO THE TRANSMIT PAYLOAD DATA INPUT INTERFACE BLOCK OF THE XRT74L74
FOR MODE 4 (NIBBLE-PARALLEL/LOOP-TIMED) OPERATION .................................................................................................. 307
FIGURE 114. BEHAVIOR OF THE TERMINAL INTERFACE SIGNALS BETWEEN THE XRT74L74 AND THE TERMINAL EQUIPMENT (MODE 4 OPERATION)
308
FRAMER OPERATING MODE REGISTER (ADDRESS = 0X00) ......................................................................................... 308
FIGURE 115. THE TERMINAL EQUIPMENT BEING INTERFACED TO THE TRANSMIT PAYLOAD DATA INPUT INTERFACE BLOCK OF THE XRT74L74
FOR MODE 5 (NIBBLE-PARALLEL/LOCAL-TIMED/FRAME-SLAVE) OPERATION .......................................................................... 309
FIGURE 116. BEHAVIOR OF THE TERMINAL INTERFACE SIGNALS BETWEEN THE XRT74L74 AND THE TERMINAL EQUIPMENT (E3, MODE 5 OPER-
ATION) ................................................................................................................................................................................ 310
FRAMER OPERATING MODE REGISTER (ADDRESS = 0X00) ......................................................................................... 310
FIGURE 117. THE TERMINAL EQUIPMENT BEING INTERFACED TO THE TRANSMIT PAYLOAD DATA INPUT INTERFACE BLOCK OF THE XRT74L74
FOR MODE 6 (NIBBLE-PARALLEL/LOCAL-TIMED/FRAME-MASTER) OPERATION ....................................................................... 311
FIGURE 118. BEHAVIOR OF THE TERMINAL INTERFACE SIGNALS BETWEEN THE XRT74L74 AND THE TERMINAL EQUIPMENT (E3 MODE 6 OPER-
ATION) ................................................................................................................................................................................ 312
FRAMER OPERATING MODE REGISTER (ADDRESS = 0X00) ......................................................................................... 312
6.2.2 THE TRANSMIT OVERHEAD DATA INPUT INTERFACE ...................................................................................... 313
FIGURE 119. THE TRANSMIT OVERHEAD DATA INPUT INTERFACE BLOCK.............................................................................................. 313
TABLE 63: A LISTING OF THE OVERHEAD BITS WITHIN THE E3 FRAME, AND THEIR POTENTIAL SOURCES ................................................ 314
TABLE 64: DESCRIPTION OF METHOD 1 TRANSMIT OVERHEAD INPUT INTERFACE SIGNALS ................................................................... 315
FIGURE 120. THE TERMINAL EQUIPMENT BEING INTERFACED TO THE TRANSMIT OVERHEAD DATA INPUT INTERFACE (METHOD 1) ......... 316
TABLE 65: THE RELATIONSHIP BETWEEN THE NUMBER OF RISING CLOCK EDGES IN TXOHCLK, (SINCE TXOHFRAME WAS LAST SAMPLED "HIGH")
TO THE E3 OVERHEAD BIT, THAT IS BEING PROCESSED ........................................................................................................ 317
FIGURE 121. ILLUSTRATION OF THE SIGNAL THAT MUST OCCUR BETWEEN THE TERMINAL EQUIPMENT AND THE XRT74L74 IN ORDER TO CON-
FIGURE THE XRT74L74 TO TRANSMIT A YELLOW ALARM TO THE REMOTE TERMINAL EQUIPMENT ........................................... 318
TABLE 66: DESCRIPTION OF METHOD 2 TRANSMIT OVERHEAD INPUT INTERFACE SIGNALS ................................................................... 319
FIGURE 122. THE TERMINAL EQUIPMENT BEING INTERFACED TO THE TRANSMIT OVERHEAD DATA INPUT INTERFACE (METHOD 2) ......... 320
TABLE 67: 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 XRT74L74 .......................................................................... 321
FIGURE 123. BEHAVIOR OF TRANSMIT OVERHEAD DATA INPUT INTERFACE SIGNALS BETWEEN THE XRT74L74 AND THE TERMINAL EQUIPMENT
(FOR METHOD 2)................................................................................................................................................................. 322
6.2.3 THE TRANSMIT E3 HDLC CONTROLLER.............................................................................................................. 322
FIGURE 124. LAPD MESSAGE FRAME FORMAT................................................................................................................................... 323
TABLE 68: THE LAPD MESSAGE TYPE AND THE CORRESPONDING VALUE OF THE FIRST BYTE, WITHIN THE INFORMATION PAYLOAD ...... 324
TXE3 CONFIGURATION REGISTER (ADDRESS = 0X30) ................................................................................................ 324
TRANSMIT E3 LAPD CONFIGURATION REGISTER (ADDRESS = 0X33).......................................................................... 325
TABLE 69: RELATIONSHIP BETWEEN TXLAPD MSG LENGTH AND THE LAPD MESSAGE SIZE ................................................................ 325
TXE3 LAPD CONFIGURATION REGISTER (ADDRESS = 0X33) ...................................................................................... 325
TRANSMIT E3 LAPD CONFIGURATION REGISTER (ADDRESS = 0X33).......................................................................... 326
TXE3 LAPD STATUS AND INTERRUPT REGISTER (ADDRESS = 0X34) .......................................................................... 326
TXE3 LAPD STATUS AND INTERRUPT REGISTER (ADDRESS = 0X34) .......................................................................... 327
VII