Datasheet

MAC/
Switch
PCS
Signal
Process
PHY
AFE
PHY Digital
XFMR
&
RJ45
CAT5 Cable
LinkPartner
M
I
I
ReverseLoopback
TLK110
SLLS901D –DECEMBER 2011–REVISED JANUARY 2014 www.ti.com
3.10.2 Far-End Loopback
Far-end (Reverse) loopback is a special test mode to allow testing the PHY from the link-partner side. In
this mode, data that is received from the link partner passes through the PHY's receiver, looped back on
the MII and transmitted back to the link partner. Figure 3-8 shows Far-end loopback functionality.
Figure 3-8. Block Diagram, Far-End Loopback Mode
The Reverse Loopback mode is selected by setting bit 4 in the BIST Control Register (BISCR), MII
register address 0x0016.
While in Reverse Loopback mode the data is looped back and also transmitted onto the MAC Interface
and all data signals that come from the MAC are ignored.
Table 3-5 describes the operating modes for Far-End Loopback.
Table 3-5. Far-End Loopback Modes
Operational MAC Int. MII Mode RMII Mode
Operational Setting Force/ANEG 10/100 Force/ANEG 10
18 Hardware Configuration Copyright © 2011–2014, Texas Instruments Incorporated
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