
XRT84L38
218
OCTAL T1/E1/J1 FRAMER
REV. 1.0.1
The table below shows functionality of the RxTSb[2:0] bits when the Receive Fractional T1 Output bit is set to
different values.
T
ABLE
43: T
HE
R
X
TS
B
[2:0]
BITS
WHEN
THE
R
ECEIVE
F
RACTIONAL
T1 O
UTPUT
BIT
IS
SET
TO
DIFFERENT
VALUES
The Receive Time-slot Indicator Clock signal (RxTSClk_n) is a multi-function output pin. When configured to
operate in normal condition (that is, when the Receive Fractional T1 Input Enable bit is equal to zero), the
RxTSClk_n is a 192KHz clock that pulses HIGH for one DS1 bit period whenever the Receive Payload Data
Output Interface block is outputting the LSB of each of the twenty-four time slots. The local Terminal Equipment
should use this clock signal to sample the RxTSb[0] through RxTSb[4] bits and identify the time-slot being
processed via the Receive Section of the framer.
When the Receive Fractional T1 Output Enable bit is equal to one, the RxTSClk_n will output gaped fractional
DS1 clock whenever Fractional DS1 payload data is present at the RxFrTD_n pin. The local Terminal
Equipment can latch in Fractional DS1 payload data at falling edge of the clock. Otherwise, this pin will be a
clock enable signal to Receive Fractional DS1 output signal (RxFrTD_n) if the framer is configured accordingly.
In this way, Fractional DS1 payload data is clocked into the Terminal Equipment using un-gaped Receive Serial
Output Clock (RxSerClk_n). A detailed discussion of the Fractional DS1 Payload Data Output Interface can be
found in later sections.
A detailed discussion of how to connect the Receive Payload Data Output Interface block to the local Terminal
Equipment with Slip Buffer enabled or disabled can be found in the later sections.
5.1.2.1
Connect the Receive Payload Data Output Interface block to the Local Terminal
Equipment if the Slip Buffer is bypassed
By setting the Slip Buffer Enable [1:0] bits of the Slip Buffer Control Register to 00 or 11, the Receive Framer
Module routes the Receive Payload Data directly to the Receive Payload Data Output Interface without
passing through the Elastic Buffer. The XRT84L38 uses the Recovered Receive Line Clock internally to carry
the Receive Payload Data directly across the whole chip. The Recovered Receive Line Clock is essentially
become timing source of the Receive Serial Clock output.
If the Slip Buffer is bypassed, the Receive Single-frame Synchronization signal is automatically configured to
be output signals. It should pulse HIGH for one DS1 bit period (648ns) at the last bit position of each DS1
frame. By triggering on the HIGH pulse on the Receive Single-frame Synchronization signal, the Terminal
Equipment can identify the end of a DS1 frame and should prepare to accept payload data of the next DS1
frame from the framer.
The Receive Multi-frame Synchronization signal should pulse HIGH for one DS1 bit period (648ns) at the last
bit position of a DS1 multi-frame. By triggering on the HIGH pulse on the Receive Multi-frame Synchronization
signal, the framer can identify the end of a DS1 super-frame and should prepare to accept payload data of the
next DS1 super-frame from the framer.
R
ECEIVE
F
RACTIONAL
T1 O
UTPUT
B
IT
= 0
R
ECEIVE
F
RACTIONAL
T1 O
UTPUT
B
IT
= 1
RxTSb[0]
Output
RxFrTD
Output
RxTSb[1]
Output
RxSig
Output
RxTSb[2]
Output
RxTS
Output