XRT72L50 Datasheet, PDF (392/471 Pages) Exar Corporation – SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER WITH HDLC CONTROLLER
REV. 1.2.1
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FIGURE 163. FLOW CHART DEPICTING HOW TO USE THE LAPD TRANSMITTER (LAPD TRANSMITTER IS CONFIGURED
TO RE-TRANSMIT THE LAPD MESSAGE FRAME REPEATEDLY AT ONE-SECOND INTERVALS)
Start
Write the Header in 0x86 to 0x89
Write the LAPD Message frame identification octet
into the first octet position within the Transmit LAPD
Message buffer (Address=0x8A)
LAPD Transmitter will generate a continuous string of
Flag Sequence bytes that will be transported via the
GC or the NR byte-fileld (user's selection)
Initiate the LAPD Message transmission
Write the PMDL Message into the remaining portion
of the Transmit LAPD Message buffer
(from 0x87 to 0xDb)
Specify the type/size of the LAPD Message frame
to be transmitted.
Write the appropriate value into bit 1 within the
Transmit E3 LAPD Configuration Register
Specify whether the outbound LAPD Message
frame is to be transported via the GC or the NR byte-
fields within each outbound E3 frame
Configure the LAPD Transmitter to repeat
transmissions of the LAPD Message frame at one
second intervals
LAPD Transmitter will compute and insert the FCS
value into the LAPD Message frame.
LAPD Transmitter will "stuff" the contents of the
PMDL Message and FCS Bytes.
LAPD Transmitter will fragment LAPD Message
frame into octets and begin to insert these into
the GC or NR byte-field (user's selection) into each
outbound E3 frame.
Complete transmission of LAPD Message frame
Generate Completion of Transmission LAPD Message
Frame Interrupt
Enable the LAPD Transmitter
Wait one second. Generate a continuous string of Flag
Sequence Bytes
Figure 164 presents the procedure (in white boxes) which the user should use in order to transmit a PMDL
Message via the LAPD Transmitter, when the LAPD Transmitter is configured to transmit a LAPD Message
frame only once, and then halt transmission.
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