Configurable LED Outputs

Note: It is especially important to note with respect to the blink-control circuit that:

the blink circuit, when enabled, exists as the LAST stage of the LED circuitry, after any (optional) signal inversion

the blink sequence occurs when the circuit input is asserted low

As a result, it is possible to select combinations of IVRT and BLINK which do not make sense or produce unexpected results, such as examples previously noted. It is recommended that BLINK only be selected for indicating ACTIVITY, COLLISION, PAUSED, or the combination LINK/ ACTIVITY signal. events/states, and that IVRT = 0b when blink is selected.

Note: Selecting the LEDCTL.MODE = LINK/ACTIVITY with BLINK = 1b selects a unique LED output expression (this configuration is meaningful ONLY when IVRT inversion is disabled). In this configuration, the LED is off (output high) if there is no LINK, on if there is LINK but no ACTIVITY, and blinking if there is LINK with ACTIVITY.

LINK_UP

(LINK & NO ACTIVITY)

 

 

 

ACTIVITY

TOGGLING DURING ACTIVITY

 

 

 

 

 

EXTERNAL

BLINK

LED

LED

CONTROL

OUTPUT

 

CIRCUIT

DRIVER

 

Figure 10-2. Blink Control

Software Developer’s Manual

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Intel PCI-X, Intel Gigabit Ethernet Controllers manual Blink Control