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PRELIMINARY
XRT79L71
462
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
overhead bit is currently being processed by the Transmit Overhead Data Input Interface block at any given
TxOHClk clock period.
When the System-Side Terminal Equipment knows which overhead bit is being
processed within a given TxOHClk clock period, it can decide when to insert the appropriate bit-value into the
Transmit Overhead Data Input Interface block and in-turn, force the Transmit DS3/E3 Framer block to insert
this same bit value into the appropriate overhead bit-position within the outbound E3 data-stream. From all of
this, the System-Side Terminal Equipment will know when it should assert the TxOHIns input pin and place the
appropriate value on the TxOH input pin of the XRT79L71.
Table 60 relates the number of rising clock edge, within the TxOHClk output signal, since the TxOHFrame
output signal was sampled "High" to the E3 Overhead Bit being processed by the Transmit Overhead Data
Input Interface block. The user can use this table as a guide for inserting the appropriate overhead bits, within
the outbound E3 data-stream, for Method 1.
TABLE 60: THE RELATIONSHIP BETWEEN THE NUMBER OF RISING CLOCK EDGES IN THE TXOHCLK SIGNAL, SINCE
THE
TXOHFRAME SIGNAL WAS LAST SAMPLED "HIGH" TO THE E3 OVERHEAD BIT THAT IS BEING PROCESSED BY THE
TRANSMIT OVERHEAD DATA INPUT INTERFACE BLOCK
NUMBER OF RISING EDGES IN
TXOHCLK SINCE TXOHFRAME
BEING SAMPLED
"HIGH"
THE OVERHEAD BIT TO BE PROCESSED BY THE TRANSMIT
OVERHEAD DATA INPUT INTERFACE BLOCK
CAN THIS OVERHEAD BIT BE
ACCEPTED BY THE
XRT79L71,
AND INSERTED INTO THE
OUTBOUND
E3 DATA-STREAM?
0 (TxOHClk, Clock Edge is
coincident with the TxO-
HFrame signal being sampled
"High")
FA1 Byte, Bit 1 (MSB)
NO
1
FA1 Byte, Bit 2
NO
2
FA1 Byte, Bit 3
NO
3
FA1 Byte, Bit 4
NO
4
FA1 Byte, Bit 5
NO
5
FA1 Byte, Bit 6
NO
6
FA1 Byte, Bit 7
NO
7
FA1 Byte, Bit 8 (LSB)
NO
8
FA2 Byte, Bit 1 (MSB)
NO
9
FA2 Byte, Bit 2
NO
10
FA2 Byte, Bit 3
NO
11
FA2 Byte, Bit 4
NO
12
FA2 Byte, Bit 5
NO
13
FA2 Byte, Bit 6
NO
14
FA2 Byte, Bit 7
NO
15
FA2 Byte, Bit 8 (LSB)
NO
16
EM Byte, Bit 1 (MSB)
NO
17
EM Byte, Bit 2
NO
18
EM Byte, Bit 3
NO
19
EM Byte, Bit 4
NO