XRT72L56 Datasheet, PDF (391/486 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
Maintenance Data Link (PMDL) bits can either be
sourced from the Transmit LAPD Controller/Buffer or
via the Transmit Overhead Data Input Interface.
Table 72 lists the Overhead Bits within the DS3 frame.
Additionally, this table also indicates whether or not
these overhead bits can be sourced by the Transmit
Overhead Data Input Interface or not.
TABLE 72: A LISTING OF THE OVERHEAD BITS WITHIN THE E3 FRAME, AND THEIR POTENTIAL SOURCES, WITHIN THE
XRT72L56 IC
OVERHEAD BIT
FA1 - Bit 7
INTERNALLY GENERATED
Yes
ACCESSIBLE VIA THE TRANSMIT OVERHEAD
DATA INPUT INTERFACE
No
BUFFER/REGISTER
ACCESSIBLE
Yes*
FA1 - Bit 6
Yes
No
Yes
FA1 - Bit 5
Yes
No
Yes*
FA1 - Bit 4
Yes
FA1 - Bit 3
Yes
No
Yes*
No
Yes
FA1 - Bit 2
Yes
No
Yes
FA1 - Bit 1
Yes
No
Yes+
FA1 - Bit 0
Yes
No
Yes
FA2 - Bit 7
Yes
No
Yes
FA2 - Bit 6
Yes
No
Yes
FA2 - Bit 5
Yes
No
Yes
FA2 - Bit 4
Yes
No
Yes
FA2 - Bit 3
Yes
No
Yes
FA2 - Bit 2
Yes
No
Yes
FA2 - Bit 1
Yes
No
Yes
FA2 - Bit 0
Yes
No
Yes
EM - Bit 7
Yes
Yes
Yes
EM - Bit 6
Yes
Yes
Yes
EM - Bit 5
Yes
Yes
Yes
EM - Bit 4
Yes
Yes
Yes
EM - Bit 3
Yes
Yes
Yes
EM - Bit 2
Yes
Yes
Yes
EM - Bit 1
Yes
Yes
Yes
EM - Bit 0
Yes
Yes
Yes
TR - Bit 7
No
Yes
Yes
TR - Bit 6
No
Yes
Yes
TR - Bit 5
No
Yes
Yes
TR - Bit 4
No
Yes
Yes
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