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Configurable LED Outputs — Intel
®
82575EB Gigabit Ethernet Controller
324632-003 Intel
®
82575EB Gigabit Ethernet Controller
Revision: 2.1 Software Developer’s Manual and EEPROM Guide
January 2011 277
12.0 Configurable LED Outputs
The 82575 implements four output drivers intended for driving external LED circuits per port. Each LAN
device provides an independent set of LED outputs (these pins and their function are bound to a specific
LAN device). Each of the four LED outputs can be individually configured to select the particular event,
state, or activity that is indicated on that output. n addition, each LED can be individually configured for
output polarity as well as for blinking versus non-blinking (steady-state) indication.
The configuration for LED outputs is specified via the LEDCTL register. In addition, the hardware-default
configuration for all the LED outputs can be specified via EEPROM fields, thereby supporting LED
displays configurable to a particular OEM preference.
Each of the four LED’s can be configured to use one of a variety of sources for output indication. The
MODE bits control the LED source:
• LINK_100/1000 is asserted when link is established at either 100 or 1000 Mb/s.
• LINK_10/1000 is asserted when link is established at either 10 or 1000 Mb/s.
• LINK_UP is asserted when any speed link is established and maintained.
• ACTIVITY is asserted when link is established and packets are being transmitted or received.
• LINK/ACTIVITY is asserted when link is established AND there is NO transmit or receive activity
• LINK_10 is asserted when a 10 Mb/s link is established and maintained.
• LINK_100 is asserted when a 100 Mb/s link is established and maintained.
• LINK_1000 is asserted when a 1000 Mb/s link is established and maintained.
• FULL_DUPLEX is asserted when the link is configured for full duplex operation.
• COLLISION is asserted when a collision is observed.
• PAUSED is asserted when the 82575's transmitter is flow controlled.
• LED_ON is always asserted; LED_OFF is always de-asserted.
The IVRT bits enable the LED source to be inverted before being output or observed by the blink-control
logic. LED outputs are assumed to normally be connected to the negative side (cathode) of an external
LED.
The BLINK bits control whether the LED should be blinked (either 200 ms on and 200 ms off or 83 ms
on and 83 ms off) while the LED source is asserted. The blink control might be especially useful for
ensuring that certain events, such as ACTIVITY indication, cause LED transitions, which are sufficiently
visible to a human eye.
Note: The LINK/ACTIVITY source functions slightly different from the others when BLINK is
enabled. The LED is off if there is no LINK, on if there is LINK and no ACTIVITY, and blinking
if there is LINK and ACTIVITY.
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