Configurable LED Outputs

Configurable LED Outputs

10

10.1Configurable LED Outputs1

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.

10.1.1Selecting an LED Output Source

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 Section 10.1.2 for details.

LINK_UP

 

 

 

 

ACTIVITY

 

 

 

 

COLLISION

 

 

 

 

 

 

 

 

EXTERNAL

 

(OPTIONAL)

(OPTIONAL)

LED

LED

 

 

VCC/LED_OFF

POLARITY

BLINK

OUTPUT

 

INVERSION

CONTROL

DRIVER

 

 

 

GND/LED_ON

 

CIRCUIT

 

 

 

 

 

 

Figure 10-1. Selecting an LED Output Source

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

Software Developer’s Manual

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Intel PCI-X, Intel Gigabit Ethernet Controllers manual Configurable LED Outputs1, Selecting an LED Output Source