
á
XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER WITH HDLC CONTROLLER
REV. 1.2.1
164
Transmit FEAC Processor will generate an interrupt (if enabled) to the local P/C upon completion of the 10th
transmission of the FEAC Message. The purpose of having the Framer generate this interrupt is to let the local
P/C know that the Transmit FEAC Processor is now available and ready to transmit a new FEAC message.
The Transmit FEAC Processor continues to send the FEAC Code Message even after the 10th transmission
until the TxFEAC processor is disabled or a new FEAC code transmission is initiated.
If the TxFEAC processor is disabled, the FEAC bit contains a “1” which the remote Rx side interprets as an idle
FEAC message.
Figure 49 presents a flow chart depicting how to use the Transmit FEAC Processor.
NOTE: The FEAC processor starts transmitting the last FEAC message when enabled. Execute the “Initiate Transmission
of the Outbound FEAC Message” step without delay to prevent unintended incorrect transmission. Rx FEAC
prossecor validates a FEAC code upon receiving the same code 8 times.
NOTE: For a detailed description of the Receive FEAC Processor within the Receive DS3 HDLC Controller block, please
see
4.2.3.2
Message-Oriented Signaling (e.g., LAP-D) processing via the Transmit DS3 HDLC
Controller
The LAPD Transmitter within the Transmit DS3 HDLC Controller Block allows the user to transmit Path
Maintenance Data Link (PMDL) messages to the remote terminal via the outbound DS3 Frames.
The
FIGURE 49. A FLOW CHART DEPICTING HOW TO TRANSMIT A FEAC MESSAGE VIA THE FEAC TRANSMITTER
En a b le th e T ran sm it F E A C Pro c e s s o r
T his is accom p lishe d by writin g xxxxx1xx
into the T xD S3 F EAC C onfig uration and
S ta tus R e gister.
Has the
16 -bit F E A C M e sage
be en transm itte d to
the re m ote term in al
10 tim es ?
Invo ke the T ransm it F E A C Inte rrupt
Service R o utine
G ene ra te th e T ran sm it FE A C In terrup t
ST A R T
1
NO
Is T ran sm ission
of the 1 6-b it
F EAC M essage
com p le te?
W rite S ix -B it O u tb o u n d F E A C V a lu e In to
th e T x D S 3 F E AC R e g ister
T he a ddress is locate d at 0x32.
In itia te Tra n s m is s ion o f th e o u tbou nd
F E AC M essa g e
T his is accom p lishe d by writin g xxxxx1xx
into the T xD S3 F EAC C onfig uration and
S ta tus R e gister.
T ran sm it FE A C Processor Encapsulates the O utbound
F E A C value into a 1 6 bit F ra m ing S tructu re.
T ran sm it FE A C P rocessor P ro ce eds to Insert the 16 bit
M e ssa ge (in a b it-by-bit M ann er) into the F E A C F ie lds
of e ach ou tbou nd D S 3 Fram e.
NO TE :
T h e F E AC p ro c esso r s tarts tran sm ittin g
th e last F E AC m e s sag e w h en en ab le d .
Ex ec u te th e “ In itia te T ran sm is s io n o f
th e O u tb o u n d F E AC M ess ag e ” ste p
w ithou t de la y to pre v e n t un in te nd e d
in co rrect tran s m issio n . R x F E AC
p ro s seco r v a lid ate s a F E AC co d e u p o n
re c e iv ing th e s a m e c ode 8 tim e s .
YES
NO
YES
1