Datasheet

KSZ8873MLL/FLL/RLL
DS00002348A-page 36  2017 Microchip Technology Inc.
3.13 Loopback Support
The KSZ8873MLL/FLL/RLL provides loopback support for remote diagnostic of failure. In loopback mode, the speed at
both PHY ports needs to be set to 100BASE-TX. Two types of loopback are supported: Far-end Loopback and Near-
end (Remote) Loopback.
3.13.1 FAR-END LOOPBACK
Far-end loopback is conducted between the KSZ8873MLL/FLL/RLL’s two PHY ports. The loopback is limited to few
package a time for diagnosis purpose and cannot support large traffic. The loopback path starts at the “Originating.”
PHY port’s receive inputs (RXP/RXM), wraps around at the “loopback” PHY port’s PMD/PMA, and ends at the “Origi-
nating” PHY port’s transmit outputs (TXP/TXM).
Bit [0] of registers 29 and 45 is used to enable far-end loopback for ports 1 and 2, respectively. Alternatively, the MII
Management register 0, bit [14] can be used to enable far-end loopback.
The far-end loopback path is illustrated in Figure 3-13.
FIGURE 3-12: SPI MULTIPLE READ
SPIQ
SPIC
SPID
SPIS_N
00000011X A7 A6 A5 A4 A3 A2 A1
A0
D7 D6 D5 D4 D3 D2 D1 D0
READ COMMAND READ ADDRESS Byte 1
XXXXXXXXXXXXXXX
X
Byte 2 Byte 3 Byte N
X X X X X X X X
XXXXXXXX
D7 D6 D5 D4 D3 D2 D1 D0
D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D2 D1 D0
SPIQ
SPIC
SPID
SPIS_N