Table 20-21. Advertised Mode Configurations
Advertised Mode
ANMODE
ANEN value
10Base-T, Half/Full-Duplex
0x0
1
100Base-TX, Half/Full-Duplex
0x1
1
10Base-T, Half Duplex 100Base-TX, Half Duplex
0x2
1
10Base-T, Half/Full-Duplex 100Base-TX, Half/Full-Duplex
0x3
1
20.4.2.2
Auto-MDIX
The PHY automatically determines whether or not it needs to cross over between pairs so that an
external crossover cable is not required. If the PHY communicates with a device that implements
MDI/MDIX crossover, a random algorithm as described in IEEE 802.3 determines which device
performs the crossover. Auto-MDIX is enabled by default at reset. If a different auto-MDIX
configuration is required other than the reset initialization, the application can customize the
configuration as described in “Custom Configuration” on page 1466. Neither Auto- Negotiation nor
Auto-MDIX is required to be enabled in forcing crossover of the MDI pairs. Auto-MDIX can be used
in the forced 100Base-TX mode. Because in modern networks all the nodes are 100Base-TX, having
the Auto-MDIX working in the forced 100Base-TX mode resolves the link faster without the need
for the long Auto-Negotiation period.
20.4.2.3
Isolate Mode
The PHY can be put into Isolate mode by writing
ISOLATE
bit of the
Ethernet PHY Basic Mode
Control - MR0 (EPHYBMCR)
register, address 0x000. When in the Isolate mode, the PHY does
not respond to packet data present at the internal interface to the Ethernet MAC. When in isolate
mode, the PHY continues to respond to all management transactions and the PMD output pair does
not transmit packet data, but continues to source 100Base-TX scrambled idles or 10Base-T normal
link pulses. The PHY can auto-negotiate or parallel detect on the receive signal at the PMD input
pair. A valid link can be established for the receiver even when the PHY is in Isolate mode.
20.4.2.4
LED Interface
The PHY supports three configurable Light Emitting Diode (LED) pins to indicate link status of a
port. The
Ethernet PHY LED Configuration - MR37 (EPHYLEDCFG)
register, address 0x025 can
be used to assign different functions to each LED. Each LED can be configured to be active during
one of these events:
■ Link OK (0x0)
■ RX/TX Activity (0x1)
■ TX Activity (0x2)
■ RX Activity (0x3)
■ Collision (0x4)
■ 100-BASE TX speed (0x5)
■ 10-Base TX speed (0x6)
■ Full Duplex (0x7)
■ Link OK/Blink on TX/RX Activity (0x8)
1459
June 18, 2014
Texas Instruments-Production Data
Tiva
™
TM4C1294NCPDT Microcontroller