LAN83C183 Datasheet, PDF (42/113 Pages) SMSC Corporation – FAST ETHERNET PHYSICAL LAYER DEVICE

halted, and the Half/Full Duplex modes do not change. Diagnostic loopback cannot
be enabled when in the FBI mode (see Section 1.2.2.2, “FBI Interface,” page 1-19).
1.6 REPEATER MODE
The LAN83C183 uses the standard MII as the physical interface for MII-based
repeater cores.
The LAN83C183 has one predefined repeater mode. To enable this mode, assert the
RPTR pin. When this repeater mode is enabled with the RPTR pin:
• TX_EN to CRS loopback is disabled
• AutoNegotiation is disabled
• 100 Mbits/s operation is enabled
• Half-Duplex operation is enabled
Note:
Enabling the repeater mode with the RPTR pin is only one of many pos-
sible repeater modes available on the device. Other repeater modes
are available when appropriate register bits are set to enable or disable
the desired functions for a given repeater mode type.
For additional information, see ?Application Note?.
1.7 10/100 MBITS/S SELECTION
The device can be forced into either the 10 or 100 Mbits/s mode, or it can use
AutoNegotiation to autoselect 10 or 100 Mbits/s operation.
1.7.1 Forcing 10/100 Mbits/s Operation
To independently force each channel into either the 10 Mbits/s or 100 Mbits/s mode:
• Clear the ANEG_EN bit in the MI serial port Control register, and
• Appropriately set the Speed Select (SPEED) bit in the MI serial port Control
register.
Alternatively, if the ANEG pin is LOW, the SPEED pin controls the speed. Asserting
the SPEED pin HIGH forces 100 Mbits/s operation and deasserting it LOW forces 10
Mbits/s operation.
1.7.2 Autoselecting 10/100 Mbits/s Operation
The device can automatically configure itself for 10 or 100 Mbits/s mode. To do this,
it uses the AutoNegotiation algorithm to advertise and detect 10 and 100 Mbits/s
capabilities to and from a remote device. Setting the AutoNegotiation Enable
(ANEG_EN) bit in the MI serial port Control register enables AutoNegotiation.
Appropriately setting the bits in the MI serial port AutoNegotiation Advertisement
register selects the advertised speed capability. AutoNegotiation functionality is
described in more detail in Section 1.2.11, “Link Integrity and AutoNegotiation”.
1.7.3 10/100 Mbits/s Indication
The device can be programmed such that the operation speed (10 or 100 Mbits/s)
appears on the PLED0n pin. To do this, appropriately set the Programmable LED Out-
put Select bits in the MI serial port Configuration 2 register as described in Table 1.9.
When the PLED0n pin is programmed to be speed detect output, it is asserted LOW
when the device is configured for 100 Mbit/s operation. The PLED0n output has both
pullup and pulldown driver transistors and a weak pullup resistor, so it can drive an
LED from either V_DD or GND and can also drive a digital input.
SMSC DS – LAN83C183
42
Rev. 12/14/2000