XRT72L50 Datasheet, PDF (361/471 Pages) Exar Corporation – SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

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XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER WITH HDLC CONTROLLER
REV. 1.2.1
1. Set the NibIntf input pin "Low".
2. Set the TimRefSel[1:0] bit fields (within the Framer Operating Mode Register) to "00" as illustrated below.
Framer Operating Mode Register (Address = 0x00)
BIT 7
Local Loop-back
BIT 6
DS3/E3*
R/W
R/W
0
0
BIT 5
Internal LOS
Enable
R/W
1
BIT 4
RESET
R/W
0
BIT 3
Interrupt
Enable Reset
R/W
1
BIT2
Frame Format
R/W
1
BIT 1
BIT 0
TimRefSel[1:0]
R/W
R/W
0
0
3. Interface the XRT72L50, to the Terminal Equipment, as illustrated in Figure 145.
6.2.1.2 Mode 2 - The Serial/Local-Timed/Frame-Slave Mode Behavior of the XRT72L50
If the XRT72L50 has been configured to operate in this mode, then the XRT72L50 will function as follows.
A. Local Timing - Uses the TxInClk signal as the Timing Reference
In this mode, the Transmit Section of the XRT72L50 will use the TxInClk signal as its timing reference.
B. Serial Mode
The XRT72L50 will receive the E3 payload data, in a serial manner, via the TxSer input pin. The Transmit
Payload Data Input Interface (within the XRT72L50) will latch this data into its circuitry, on the rising edge of the
TxInClk input clock signal.
C. Delineation of Outbound E3 frames (Frame Slave Mode)
The Transmit Section of the XRT72L50 will use the TxInClk input as its timing reference, and will use the
TxFrameRef input signal as its framing reference. In other words, the Transmit Section of the XRT72L50 will
initiate frame generation upon the rising edge of the TxFrameRef input signal).
D. Sampling of payload data, from the Terminal Equipment
In Mode 2, the XRT72L50 will sample the data, at the TxSer input pin, on the rising edge of TxInClk.
Interfacing the Transmit Payload Data Input Interface block of the XRT72L50 to the Terminal Equipment
for Mode 2 Operation
Figure 147 presents an illustration of the Transmit Payload Data Input Interface block (within the XRT72L50)
being interfaced to the Terminal Equipment, for Mode 2 operation.
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