XRT74L73 Datasheet, PDF (62/488 Pages) Exar Corporation – 3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER

XRT74L73
3 CHANNEL, ATM UNI/PPP DS3/E3 FRAMING CONTROLLER
REV. P1.0.1
PRELIMINARY
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
XRT74L73 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
0110 - 1111
Reserved
OPERATION CONTROL REGISTER - BYTE 0 (ADDRESS = 0X0103)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
Transmit
UTOPIA
PLL OFF
Receive
UTOPIA
PLL OFF
Reserved
PPP/ATM*
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
BIT 1
Reserved
R/W
0
BIT 0
Software
RESET*
R/W
0
BIT NUMBER
NAME
7
Transmit UTOPIA PLL
OFF
6
Receive UTOPIA PLL
OFF
5-3
Unused
2
PPP/ATM*
1
Reserved
TYPE
R/W
DESCRIPTION
R/W
R/O
R/W PPP/ATM UNI Mode Select:
This READ-WRITE bit-field permits the user to configure the
XRT74L73 device 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 XRT74L73 device.
0 - Configures the "Dedicated" UTOPIA/POS-PHY bus to oper-
ate in the UTOPIA (ATM) Mode.
1 - Configures the "Dedicated" UTOPIA/POS-PHY Bus to oper-
ate in the POS-PHY Mode.
NOTE: This bit-field is ignored if Bit 3 (Dual-Bus) within the
"Operation Control Register - Byte 3" is set to "1".
R/O
63