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PRELIMINARY
XRT79L71
406
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
In order to accomplish this, the Receive Overhead Data Output Interface block has numerous output pins.
Table 48 presents a list and a brief definition of each of these pins.
TABLE 48: LIST AND DESCRIPTION OF THE PINS ASSOCIATED WITH THE RECEIVE OVERHEAD DATA OUTPUT
INTERFACE BLOCK
SIGNAL NAME
PIN/BALL
NUMBER
TYPE
DESCRIPTION
RxOH
C7
O
Receive Overhead Data Output Interface block - Data Output pin:
The exact approach that one should sample this output pin depends
from the "Receive Overhead Data Output Interface block, as described
below.
If Method 1 is used:
The XRT79L71 outputs the overhead bits, within the incoming E3 data-
stream, via this output pin. The Receive Overhead Data Output Inter-
face block will output a given bit, upon the falling edge of RxOHClk.
Hence, the "System-Side Terminal Equipment" should be designed (or
configured) to sample the data, at this pin, upon the rising edge of RxO-
HClk.
If Method 2 is used:
The XRT79L71 outputs the overhead bits, within the incoming E3 data-
stream, via this output pin. The Receive Overhead Data Output Inter-
face block will assert the "RxOHEnable" output pin (for one "RxClk"
period) whenever the data, residing on the "RxOH" output pin has
become stable and is safe for "sampling". In this case, the user should
design (or configure) the System-Side Terminal Equipment to sample
and latch the "RxOH" data upon the falling edge of "RxClk" coincident to
whenever the "RxOHEnable" output pin is sampled "high".
The XRT79L71 will always output the E3 overhead bits via this output
pin. There are no external input pins or register bits settings available
that will disable this output pin.
RxOHClk
A7
O
Receive Overhead Data Output Interface block - Clock Output pin:
This particular output pin is only used if the Method 1 is employed to
extract overhead data from the "Receive Overhead Data Output Inter-
head bits (within the incoming E3 data-stream), via the "RxOH" output
pin, upon the falling edge of this particular clock signal. As a conse-
quence, the "System-Side Terminal Equipment" should be designed (or
configured) to sample the data, at this pin, upon the rising edge of RxO-
HClk.NOTE: This output clock signal is always active.