Datasheet

DP83630
SNLS335B –OCTOBER 2010–REVISED APRIL 2013 www.ti.com
5.3 AUTO-MDIX
When enabled, this function utilizes Auto-Negotiation to determine the proper configuration for
transmission and reception of data and subsequently selects the appropriate MDI pair for MDI/MDIX
operation. The function uses a random seed to control switching of the crossover circuitry. This
implementation complies with the corresponding IEEE 802.3 Auto-Negotiation and Crossover
Specifications.
Auto-MDIX is enabled by default and can be configured via PHYCR (19h) register, bits [15:14].
Neither Auto-Negotiation nor Auto-MDIX is required to be enabled in forcing crossover of the MDI pairs.
Forced crossover can be achieved through the FORCE_MDIX bit, bit 14 of PHYCR (19h) register.
5.4 AUTO-CROSSOVER IN FORCED MODE
When enabled, this function operates in a manner similar to Auto-MDIX. If no link activity is seen,
switching of the crossover circuitry is based on a random seed. Valid link activity can be link pulses (Auto-
Negotiation link pulse or 10M link pulses) or 100M signaling. Once valid link activity is seen, crossover will
stop to allow the receive and link functions will proceed normally.
Auto-crossover in forced mode allows for shorter link times because it does not require potentially lengthy
Auto-Negotiation transactions prior to link establishment. Link establishment via Auto-crossover can be
accomplished in full or half duplex configuration, but both sides of the link must be forced to the same
duplex configuration.
Auto-crossover in forced mode is disabled by default and must be configured via PCSR (16h) register, bit
15.
Forced crossover can be achieved while Auto-crossover is enabled through the FORCE_MDIX bit, bit 14
of PHYCR (19h) register.
NOTE: Auto-MDIX and Auto-crossover in forced mode are mutually exclusive and should not be enabled
concurrently. Prior to enabling Auto-crossover in forced mode, Auto-Negotiation and Auto-MDIX should be
disabled.
5.5 PHY ADDRESS
The five PHY address strapping pins are shared with the RXD[3:0] pins and COL pin as shown below.
Table 5-2. PHY Address Mapping
Pin # PHYAD Function RXD Function
42 PHYAD0 COL
43 PHYAD1 RXD_3
44 PHYAD2 RXD_2
45 PHYAD3 RXD_1
46 PHYAD4 RXD_0
The DP83630 can be set to respond to any of 32 possible PHY addresses via strap pins. The information
is latched into the PHYCR register (address 19h, bits [4:0]) at device power-up and hardware reset. Each
DP83630 or port sharing an MDIO bus in a system must have a unique physical address.
The DP83630 supports PHY Address strapping values 0 (<00000>) through 31 (<11111>). Strapping
PHY Address 0 puts the part into Isolate Mode. It should also be noted that selecting PHY Address 0
via an MDIO write to PHYCR will not put the device in Isolate Mode. See Mill Isolate Mode for more
information.
For further detail relating to the latch-in timing requirements of the PHY Address pins, as well as the other
hardware configuration pins, refer to the Reset summary in Reset Operation.
40 Configuration Copyright © 2010–2013, Texas Instruments Incorporated
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