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PRELIMINARY
XRT79L71
320
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
Once the user executes this step, then the Transmit LAPD Controller will proceed to do the following.
a. It will parse through the contents of the Transmit LAPD Message buffer and will zero-stuff the payload
portion of the outbound PMDL Message.
b. It will compute and append the Frame Check Sequence (FCS) value, to the back end of the outbound
PMDL Message.
c. It will begin (in a byte-by-byte manner) inserting the resulting PMDL Message into the "N" bit-fields
(depending upon user selection during STEP 2), within the outbound E3 frames.
NOTES:
1.
After the user has set the Initiate Transmission of LAPD/PMDL Message bit to "1", the user is advised to (some
time later) to execute another write operation (to this register) that sets the Initiate Transmission of LAPD/PMDL
Message bit back to "0".
2.
Once the Transmit LAPD Controller has started to transmit the PMDL Message to the remote terminal, it will
denote this by setting the Transmit LAPD Controller Busy bit-field (within the Transmit E3 LAPD Status/Interrupt
register) to "1", as illustrated below.
This bit-field permits the user to poll the status of the Transmit LAPD Controller. Once the Transmit LAPD
Controller has completed the transmission of the LAPD Message frame, this bit-field will toggle back to "0".
The Mechanics of Transmitting a New LAPD Message, if the Transmit LAPD Controller has been
configured to retransmit the LAPD Message frame, repeatedly at one-second intervals
If the Transmit LAPD Controller has been configured to retransmit the LAPD Message repeatedly at one-
second intervals, then it will do the following at one-second intervals.
Parse through the contents of the Transmit LAPD Message buffer and Zero-Stuff the PMDL Message.
Read in the stuffed PMDL Message from the Transmit LAPD Message buffer.
Encapsulate this stuffed PMDL Message into a LAPD Message frame.
Transmit this LAPD Message frame to the Remote Terminal.
Transmit E3 LAPD Status/Interrupt Register (Address = 0x1134)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Unused
Initiate
Transmission
of
LAPD/PMDL
Message
Transmit
LAPD
Controller
Busy
Transmit
LAPD
Interrupt
Enable
Transmit
LAPD
Interrupt
Status
RO
R/W
RO
R/W
RUR
0
0->1
0
1
0
Transmit E3 LAPD Status/Interrupt Register (Address = 0x1134)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Unused
Initiate
Transmission
of
LAPD/PMDL
Message
Transmit
LAPD
Controller
Busy
Transmit
LAPD
Interrupt
Enable
Transmit
LAPD
Interrupt
Status
RO
R/W
RUR
0
1
0