
PRELIMINARY
XRT79L71
552
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
Setting this bit-field to "1" will configure the Receive LAPD Controller block to extract out the incoming LAPD/
PMDL Message from the NR bytes within the incoming E3 data-stream. In this setting, the Receive LAPD
Controller block will accept LAPD/PMDL Message bytes from the NR byte within each incoming E3 frame, and
it will re-assemble these bytes into a newly received LAPD/PMDL Message. Conversely, setting this bit-field to
"0" will configure the Receive LAPD Controller block to extract out the incoming LAPD/PMDL Message from
the GC bytes within the incoming E3 data-stream.
STEP 3 - Enable the Receive LAPD Controller
This is accomplished by setting Bit 2 (Receive LAPD Enable) within the Receive E3 LAPD Control Register to
"1" as depicted below.
NOTES:
1.
For normal operation, it is imperative that the user also make sure that Bit 7 (Receive LAPD Any) within this
register is set to "0".
2.
Once the user executes the above-mentioned step, then the Receive LAPD Controller will begin to extract out the
contents of any incoming LAPD/PMDL Message that is being transported via either the NR or GC byte, depending
upon user configuration, during STEP 2 within the incoming E3 data-stream. In most cases, the Receive LAPD
Controller block will simply begin to receive the Flag Sequence octet which is originating from the remote terminal.
STEP 4 - Check and verify that the Receive LAPD Controller is receiving the Flag Sequence Octets
If the Receive LAPD Controller block is currently receiving the Flag Sequence octets within the incoming E3
data-stream, then it will assert Bit 0 (Flag Present) within the Receive E3 LAPD Status Register, as depicted
below.
Receive E3 LAPD Control Register - G.832 (Address = 0x1118)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
RxLAPD Any
Unused
Receive
LAPD from
NR Byte
Receive
LAPD
Enable
Receive
LAPD
Interrupt
Enable
Receive
LAPD
Interrupt
Status
R/W
R/O
R/W
RUR
0
X
0
Receive E3 LAPD Control Register - G.832 (Address = 0x1118)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
RxLAPD Any
Unused
Receive
LAPD from
NR Byte
Receive
LAPD
Enable
Receive
LAPD
Interrupt
Enable
Receive
LAPD
Interrupt
Status
R/W
R/O
R/W
RUR
0
X
1
0