XR72L52 Datasheet, PDF (379/480 Pages) Exar Corporation – TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

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TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
XRT72L52
REV. 1.0.1
The behavior of the signals between the XRT72L52 and the Terminal Equipment for E3 Mode 6 Operation is il-
lustrated in Figure 156.
FIGURE 156. BEHAVIOR OF THE TERMINAL INTERFACE SIGNALS BETWEEN THE XRT72L52 AND THE TERMINAL
EQUIPMENT (E3 MODE 6 OPERATION)
Terminal Equipment Signals
TxInClk
E3_Nib_Clock_In
E3_Data_Out[3:0]
Tx_Start_of_Frame
Payload Nibble [1059]
Overhead Nibble [0]
E3_Overhead_Ind
XRT72L5x Transmit Payload Data I/F Signals
TxInClk
TxNibClk
TxNib[3:0]
TxNibFrame
Nibble [1059]
Overhead Nibble [0]
TxOH_Ind
Note: TxNibFrame pulses high to denote
E3 Frame Boundary.
E3 Frame Number N
E3 Frame Number N + 1
TxOH_Ind pulses high for 4 Nibble periods
How to configure the XRT72L52 into Mode 6
1. Set the NibIntfinput pin "High".
2. Set the TimRefSel[1:0] bit-fields (within the Framer Operating Mode Register) to "1X" 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
BIT2
Interrupt Frame Format
Enable Reset
R/W
R/W
1
1
BIT 1
BIT 0
TimRefSel[1:0]
R/W
R/W
1
x
3. Interface the XRT72L52, to the Terminal Equipment, as illustrated in Figure 155.
6.2.2 The Transmit Overhead Data Input Interface
Figure 157 presents a simple illustration of the Transmit Overhead Data Input Interface block within the
XRT72L52.
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