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PRELIMINARY
XRT79L71
460
REV. P2.0.0
1-CHANNEL DS3/E3 CLEAR-CHANNEL FRAMERLIU COMBO - CC/HDLC ARCHITECTURE
In order to accomplish this, the Transmit Overhead Data Input Interface block has numerous input and output
pins. Table 59 presents a list and a brief definition of each of these pins.
The Two Methods of Inserting Overhead Data Into the Transmit Overhead Data Input Interface Block
TABLE 59: LIST AND DESCRIPTION OF THE PINS ASSOCIATED WITH THE TRANSMIT OVERHEAD DATA INPUT
INTERFACE BLOCK
SIGNAL NAME
PIN/BALL
NUMBER
TYPE
DESCRIPTION
TxOHEnable
A12
O
Transmit Overhead Data - Enable Output Pin:
The Transmit Overhead Data Input Interface will assert this signal (e.g., pulse it
"High") for one TxInClk period, just prior to the instant that the Transmit Overhead
Data Input Interface block is processing an overhead bit.
This output pin will remain "Low" at all other times.
TxInClk
C10
I
Transmit Section - Timing Reference Clock Input Pin:
If the XRT79L71 has been configured to operate in the Local-Timing Mode, then this
input pin will function as the timing source for the Transmit Circuitry within the
XRT79L71.
TxOHFrame
B11
O
Transmit Overhead Input Interface Enable Input Pin:
This output pin pulses "High" whenever the Transmit Overhead Data Input Port is
processing the last bit within a given E3 frame.
TxOHIns
D10
I
Transmit Overhead Data - Insert Enable Input Pin:
Asserting this input pin (e.g., setting it "High") enables the Transmit Overhead Data
Input Interface to accept overhead data from the System-Side Terminal Equipment.
In other words, while this input pin is "High", the Transmit Overhead Data Input Inter-
face will sample the data on the TxOH input pin, upon the falling edge of either the
TxInClk or the TxOHClk clock signals.
Setting this input pin "Low" configures the Transmit Overhead Data Input Interface
block to NOT sample (e.g., ignore) the data on the TxOH input pin upon the falling
edge of either the TxInClk or the TxOHClk clock signals.
NOTE: If the System-Side Terminal Equipment attempts to insert an overhead bit that
cannot be accepted by the Transmit Overhead Data Input Interface block
(e.g., if the System-Side Terminal Equipment asserts the TxOHIns input pin
at a time whenever one of the non-insertable overhead bits are being
processed), then this particular insertion effort will be ignored.
TxOH
C11
I
Transmit Overhead Data Input Interface - Overhead Data Input Pin:
The Transmit Overhead Data Input Interface block accepts the overhead data via this
input pin and inserts this data into the appropriate overhead bit-position within the
very next outbound E3 frame. If the TxOHIns input pin is pulled "High", then the
Transmit Overhead Data Input Interface block will sample the data, residing on this
input pin, upon either the rising edge of TxInClk or the falling edge of TxOHClk
depending upon the Insertion Method used.
If the TxOHIns input pin is pulled "Low", then the Transmit Overhead Data Input
Interface block will NOT sample the data, residing on this input pin, upon the rising
edge of TxInClk nor on the falling edge of TxOHClk.
TxOHClk
B12
O
Transmit Overhead Clock Output:
This output pin functions as the "Transmit Overhead Data Input Interface" clock sig-
nal. If the Transmit Overhead Data Input Interface block is enabled by asserting the
"TxOHIns" input pin, then the Transmit Overhead Data Input Interface block will sam-
ple and latch the data (residing on the "TxOH" input pin) upon the falling edge of this
signal.