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XRT79L71
PRELIMINARY
301
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
NOTES:
1.
The shaded rows designate those Overhead bits that the XRT79L71 can be used to insert into the outbound E3
data-stream via the Transmit Overhead Data Input Interface block.
The un-shaded rows designate those
Overhead bits that the XRT79L71 CANNOT insert into the outbound E3 data-stream.
2.
The asterisk (*) indicates that these particular overhead bits will only be processed if BIP-4 processing is enabled,
within the Transmit E3 Framer Block.
TASK # 3: After the System-Side Terminal Equipment has waited the appropriate number of TxOHEnable
pulses from the TxOHFrame signal being sampled "High", it should assert the TxOHIns input signal (by pulling
it "High"). Concurrently, the System-Side Terminal Equipment should also place the appropriate value of the
overhead bit (to be inserted into the outbound E3 data-stream) onto the TxOH input signal. The Transmit
Overhead Data Input Interface block will sample and latch the data (residing on the TxOH input pin) upon the
second rising edge of TxInClk (after TxOHEnable was sampled "High").
TASK # 4: The System-Side Terminal Equipment should hold the TxOHIns input pin "High" and also hold the
value of the TxOH signal stable until the next time that the TxOHEnable output pin is sampled "High".
Afterwards, the System-Side Terminal Equipment should toggle the TxOHIns input pin "Low" and wait until
another appropriate TxOHEnable pulsing period comes up, for inserting an overhead bit into the outbound E3
data-stream.
TABLE 41: THE RELATIONSHIP BETWEEN THE NUMBER OF PULSES IN THE TXOHENABLE SIGNAL, SINCE THE
TXOHFRAME SIGNAL WAS LAST SAMPLED "HIGH" TO THE E3 OVERHEAD BIT THAT IS CURRENTLY BEING PROCESSED
BY THE
TRANSMIT OVERHEAD DATA INPUT INTERFACE BLOCK
NUMBER OF PULSES IN TXOHENABLE,
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 (TxOHEnable and TxOHFrame are
sampled "High" simultaneously)
FAS, Bit 1 (MSB)
NO
1
FAS, Bit 2
NO
2
FAS, Bit 3
NO
3
FAS, Bit 4
NO
4
FAS, Bit 5
NO
5
FAS, Bit 6
NO
6
FAS, Bit 7
NO
7
FAS, Bit 8
NO
8
FAS, Bit 9
NO
9
FAS, Bit 10 (LSB)
NO
10
A Bit
YES
11
N Bit
YES
12
BIP-4, Bit 1 (MSB)*
NO
13
BIP-4, Bit 2*
NO
14
BIP-4, Bit 3*
NO
15
BIP-4, Bit 4*
NO