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XRT79L71
PRELIMINARY
483
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
STEP 3 - Enable the Transmit LAPD Controller
This is accomplished by setting Bit 0 (Transmit LAPD Enable) within the Transmit E3 LAPD Configuration
register to "1", as illustrated below.
NOTE: Once the user executes the above-mentioned step, then the Transmit LAPD Controller will begin to transmit the Idle
Flag Sequence (e.g., a repeating string of 0x7E) via either the N bit within each outbound E3 frame.
STEP 4 - Configure the Transmit LAPD Controller to transmit a non-standard size LAPD Message.
This is accomplished by setting Bit 7 (LAPD Any) within the Transmit E3 LAPD Configuration Register to "1",
as illustrated below.
STEP 5 - Configure the Transmit LAPD Controller to Auto-Retransmit (Optional)
In some applications, it may be desirable to configure the Transmit LAPD Controller to repeatedly transmit a
PMDL Message at one-second intervals. To configure the Transmit LAPD Controller to do this, write a "1" into
Bit 3 (Auto-Retransmit) within the Transmit E3 LAPD Configuration register. This operation is depicted below.
STEP 6 - Specify the size of the outbound LAPD Message
This is accomplished by writing the size of the information payload in terms of number of bytes into the
Transmit LAPD Byte Count Register as depicted below.
Transmit E3 LAPD Configuration Register (Address = 0x1133)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
LAPD Any
Unused
Auto
Retransmit
Unused
Transmit
LAPD
Message
Length
Transmit
LAPD
Enable
R/W
RO
R/O
R/W
R/O
R/W
0
X
1
Transmit E3 LAPD Configuration Register (Address = 0x1133)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
LAPD Any
Unused
Auto
Retransmit
Unused
Transmit
LAPD
Message
Length
Transmit
LAPD
Enable
R/W
RO
R/O
R/W
R/O
R/W
1
0
X
1
Transmit E3 LAPD Configuration Register (Address = 0x1133)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
LAPD Any
Unused
Auto
Retransmit
Unused
Transmit
LAPD
Message
Length
Transmit
LAPD
Enable
R/W
RO
R/O
R/W
R/O
R/W
1
0
1
0
X
1