XRT74L73 Datasheet, PDF (321/488 Pages) Exar Corporation – 3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER

PRELIMINARY
XRT74L73
3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER
REV. P1.0.1
FRAMER OPERATING MODE REGISTER (ADDRESS = 0X00)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
Local Loopback DS3/E3*
Internal
LOS
Enable
RESET
Interrupt
Enable Reset
R/W
R/W
R/W
R/W
R/W
0
0
1
0
1
BIT 2
Frame Format
R/W
0
BIT 1
BIT 0
TimRefSel[1:0]
R/W
R/W
1
1
This action will prevent the LAPD Transmitter from
generating its own One-Second interrupt (following
each transmission of the LAPD Message frame).
2. Enable the One-Second Interrupt
This can be done by writing a “1” into Bit 0 (One-Sec-
ond Interrupt Enable) within the Block Interrupt En-
able Register, as depicted below.
BLOCK INTERRUPT ENABLE REGISTER (ADDRESS = 0X04)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
RxDS3/E3
Interrupt
Enable
Not Used
TxDS3/E3
Interrupt
Enable
One-Second
Interrupt
Enable
R/W
RO
RO
RO
RO
RO
R/W
R/W
0
0
0
0
0
0
0
0
3. Write the new message into the Transmit LAPD
Message buffer immediately after the occurrence
of the One-Second Interrupt
By synchronizing the writes to the Transmit LAPD
Message buffer to occur immediately after the occur-
rence of the One-Second Interrupt, the user avoids
conflicting with the One-Second transmission of the
LAPD Message frame, and will transmit the correct
(uncorrupted) PMDL Message to the Remote LAPD
Receiver.
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