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XRT79L71
PRELIMINARY
409
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
REV. P2.0.0
Table 49 relates the number of rising clock edges, within the "RxOHClk" output signal, since the "RxOHFrame"
output signal was sampled "high" to the DS3 Overhead Bit being output via the RxOH output pin (of the
Receive Overhead Data Output Interface block), for Method 1.
NOTE: The asterisk (*) indicates that these particular overhead bits will only be processed if BIP-4 processing is enabled,
within the Receive E3 Framer Block.
5.3.4.2
Operating the Receive Overhead Data Output Interface block using Method 2 - The
"RxClk/RxOHEnable" Method
This particular method is referred to as the "RxClk/RxOHEnable" method for the following reasons.
a. The System-Side Terminal Equipment will use the "RxOHEnable" output pin (form the Receive
Overhead Data Output Interface block) to keep track of which overhead bit is being processed by the
Receive Overhead Data Output Interface (via the RxOH output pin) as any given time.
b. The System-Side Terminal Equipment must use the falling edge of "RxClk" in order to sample and latch
the data residing on the "RxOH" output pin.
If "Method 2" is used, the "System-Side" Terminal Equipment will need to interface to the following "Receive
Overhead Data Output Interface" pins.
RxOH
RxOHFrame
TABLE 49: THE RELATIONSHIP BETWEEN THE NUMBER OF RISING CLOCK EDGES IN THE RXOHCLK SIGNAL, SINCE
THE
RXOHFRAME SIGNAL WAS LAST SAMPLED "HIGH" TO THE E3 OVERHEAD BIT THAT IS BEING PROCESSED BY THE
RECEIVE OVERHEAD DATA OUTPUT INTERFACE BLOCK
NUMBER OF RISING EDGES IN RXOHCLK SINCE RXOHFRAME
BEING SAMPLED
"HIGH
"THE OVERHEAD BIT TO BE OUTPUT BY THE RECEIVE
OVERHEAD DATA OUTPUT INTERFACE BLOCK
0 (RxOHClk, Clock Edge is coincident with the "RxO-
HFrame" signal being sampled "high")
FAS, Bit 1 (MSB)
1
FAS, Bit 2
2
FAS, Bit 3
3
FAS, Bit 4
4
FAS, Bit 5
5
FAS, Bit 6
6
FAS, Bit 7
7
FAS, Bit 8
8
FAS, Bit 9
9
FAS, Bit 10 (LSB)
10
A Bit
11
N Bit
12
BIP-4, Bit 1 (MSB)*
13
BIP-4, Bit 2*
14
BIP-4, Bit 3*
15
BIP-4, Bit 4 (LSB)*