Intel Gigabit Ethernet Controllers ユーザーズマニュアル

179

The PCI/PCI-X Family of Gigabit Ethernet Controller’s MAC implements four output drivers 
intended for driving external LED circuits. Each MAC’s four LED outputs can be individually 

configured to select the particular event, state, or activity that is indicated on that output. In 

addition, each LED can be individually configured for output polarity as well as for blinking vs. 
non-blinking (steady-state) indication.

The configuration for LED outputs is specified via the LEDCTL register. In addition, the 

hardware-default configuration for two of the LED outputs, LED0/LINK_UP# and LED2/

LINK100# can be specified via EEPROM fields, thereby supporting LED displays configurable to 
a particular OEM preference.

Each of the four LED indications can be independently configured. The LEDCTL register MODE 
field corresponding to each LED selects the expression generating the LED output. The LED 

outputs are, by default, active low; it is assumed they are connected to the negative side (cathode) 

of an external LED. They will, by default, output a low value upon the assertion of the event (such 
as COLLISION) or state (such as LINK1000#) selected. Note that the active sense of the LED 

outputs can be inverted). See 

 for details.

1.

Section 10 does not apply to the 82544GC/EI.

 

 

 

 

LINK_UP

ACTIVITY

COLLISION

VCC/LED_OFF

GND/LED_ON

(OPTIONAL)
POLARITY
INVERSION

(OPTIONAL)
BLINK
CONTROL
CIRCUIT

LED
OUTPUT
DRIVER

EXTERNAL
LED