82598EB Datasheet, PDF (284/596 Pages) Intel Corporation – Intel® 82598EB 10 Gigabit Ethernet Controller Datasheet

Intel^® 82598EB 10 GbE Controller - LED's
Note:
All functions within the 82598 have to adhere to the tag encoding rules for DCA writes. Even
if a given function is not capable of DCA, but other functions are capable of DCA, memory
writes from the non-DCA function must set the tag field to 11111b.
3.5.7 LED's
The 82598 implements four output drivers intended for driving external LED circuits per port. Each of
the four LED outputs can be individually configured to select the particular event, state, or activity,
which is indicated on that output. In 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 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 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 (on for 200 ms, then off for 200 ms) while
the LED source is asserted. Note that you must have link in order for the LEDs to blink. To ensure you
have link, set the Force Link Up (FLU) bit when you want to blink the LEDs. When you want to stop
blinking, reset the FLU bit to 0b. The blink control can be especially useful for ensuring that certain
events, such as ACTIVITY indication, cause LED transitions, which are sufficiently visible by 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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