
PRELIMINARY
XRT79L71
558
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
STEP 2 - Select either the NR or the GC byte as the LAPD Channel.
The user can accomplish this by writing the appropriate value into Bit 3 (Receive LAPD from NR Byte), within
the Receive E3 LAPD Control Register, as depicted below.
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.
STEP 4 - Configure the Receive LAPD Controller to receive a non-standard size LAPD Message
This is accomplished by setting Bit 7 (RxLAPD Any) within the Receive E3 LAPD Control Register, to "1", as
depicted below.
Framer Operating Mode Register (Address = 0x1100)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Local
Loop-back
DS3/E3*
Internal LOS
Enable
RESET
Direct
Mapped
ATM
Frame For-
mat
Timing Reference Select
[1:0]
R/W
X
0
X
0
X
1
X
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