VSC8601 Datasheet
Functional Descriptions
and 0.8 determine the device operating speed and duplex mode. For more information
about configuring auto-negotiation, see “IEEE Standard and Main Registers,” page 38.
3.5
Manual MDI/MDI-X Setting
As an alternative to automatic MDI/MDI-X detection (using HP Auto-MDIX technology),
you can force the PHY to select MDI or MDI-X using the following scripts.
Format:
Phywrite ( register(dec), data(hex) )
Phywritemask ( register(dec), data(hex), mask(hex) )
To force MDI:
Phywrite ( 31, 0x2A30 )
Phywritemask ( 5, 0x0010, 0x0018 )
Phywrite ( 31, 0x0000 )
To force MDI-X:
Phywrite ( 31, 0x2A30 )
Phywritemask ( 5, 0x0018, 0x0018 )
Phywrite ( 31, 0x0000 )
To resume MDI/MDI-X setting based on register 18, bits 7 and 5:
Phywrite ( 31, 0x2A30 )
Phywritemask ( 5, 0x0000, 0x0018 )
Phywrite ( 31, 0x0000 )
3.6
Automatic Crossover and Polarity Detection
For trouble-free configuration and management of Ethernet links, the VSC8601 device
includes a robust, automatic, media-dependent and crossed media-dependent
detection feature, HP Auto-MDIX, in all of its three available speeds (10BASE-T,
100BASE-T, and 1000BASE-T). The function is fully compliant with clause 40 of the IEEE
standard 802.3-2002.
Additionally, the device detects and corrects polarity errors on all MDI pairs—a useful
capability that exceeds the requirements of the standard.
Both HP Auto-MDIX detection and polarity correction are enabled in the device by
default. The default settings are adjustable using device register bits 18.5:4. Status
bits for each of these functions are located in register 28.
Revision 4.1
September 2009
Page 20
VITESSE [ VITESSE SEMICONDUCTOR CORPORATION ]
