XRT79L71_1 Datasheet, PDF (35/434 Pages) Exar Corporation – 1-CHANNEL DS3/E3 ATM UNI/PPP/CLEAR-CHANNEL FRAMER IC -

REV. 1.0.0
XRT79L71
1-CHANNEL DS3/E3 ATM UNI/PPP/CLEAR-CHANNEL FRAMER IC - REGISTER/MAP DESCRIPTION
BIT NUMBER
NAME
3-0
Loop-back Control [3:0]
TYPE
R/W
DESCRIPTION
Loop-back Mode Select:
These READ/WRITE bit-fields permit the user to configure the
XRT79L71 to operate in any of the following loop-back modes.
• Local Medium Loop-back
• Remote Host Loop-back
The following table presents the contents of these bit-fields and
the corresponding Loop-back Modes.
Loop-back Control [3:0] Resulting Loop-back Mode
0000 - 0011
Reserved
0100
Local Medium Loop-back Mode
0101
Remote Host Loop-back Mode
0101 - 1111
Reserved
NOTE: The Local Medium Loop-back Mode is only available if
the XRT79L71 has been configured to operate in the
ATM UNI or in the PPP Modes
Operation Control Register - Byte 0 (Address = 0x0103)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
Reserved
Reserved
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
BIT 2
PPP/ATM*
BIT 1
Reserved
R/W
R/W
0
0
BIT 0
Software
RESET
R/W
0
BIT NUMBER
NAME
7-6
Reserved
5-3
Reserved
2
PPP/ATM*
1
Reserved
TYPE
R/W
R/O
R/W
R/O
DESCRIPTION
Set to "1" for Normal Operation.
PPP/ATM UNI Mode Select:
This READ-WRITE bit-field permits the user to configure the
XRT79L71 to operate in either the ATM UNI or PPP Mode.
If Bit 3 (Dual Bus), within the Operation Control Register - Byte 3
is set to "0", then this bit-field will then dictate the operating
mode of the XRT79L71.
0 - Configures the XRT79L71 to operate in the ATM UNI Mode.
1 - Configures the XRT79L71 to operate in the PPP Mode.
NOTE: This bit-field is ignored if Bit 0 (Configuration Control)
within the Operation Control Register - Byte 3 is is set to
"1".
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