LAN9250 datasheet(385/421 Pages) MICROCHIP

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 2015 Microchip Technology Inc.

DS00001913A-page 385

LAN9250

16.3

LED Operation

GPIO[2:0] can be individually selected to function as a LED. These pins are configured as LED outputs by setting the

corresponding LED Enable 2-0 (LED_EN[2:0]) bit in the LED Configuration Register (LED_CFG). When configured as

an LED, the pin is either a push-pull or open-drain / open-source output and the GPIO related input buffer and pull-up

are disabled. The default configuration, including polarity, is determined by input straps or EEPROM entries. Refer to

Section 7.0, "Configuration Straps," on page 54 for additional information.

The functions associated with each LED pin are configurable via the LED Function 2-0 (LED_FUN[2:0]) bits of the LED

Configuration Register (LED_CFG). These bits allow the configuration of each LED pin to indicate various port related

functions. The behaviors of each LED for each LED Function 2-0 (LED_FUN[2:0]) configuration are described in the

following tables. Detailed definitions for each LED indication type are provided in Section 16.3.1.

The default values of the LED Function 2-0 (LED_FUN[2:0]) and LED Enable 2-0 (LED_EN[2:0]) bits of the LED Con-

figuration Register (LED_CFG) are determined by the LED_fun_strap[2:0] and LED_en_strap[2:0] configuration straps.

For more information on the LED Configuration Register (LED_CFG) and its related straps, refer to Section 16.4.1, "LED

Configuration Register (LED_CFG)," on page 387.

All LED outputs may be disabled by setting the LED Disable (LED_DIS) bit in the Power Management Control Register

(PMT_CTRL). Open-drain / open-source LEDs are un-driven. Push-pull LEDs are still driven but are set to their inactive

state.

The various LED indication functions listed in the previous tables are described in the following section.

16.3.1

LED FUNCTION DEFINITIONS

The following LED rules apply :

• “Active” is defined as the pin being driven to the opposite value latched at reset on the related hard-straps. The

LED polarity cannot be modified via soft-straps.

• “Inactive” is defined as the pin not being driven.

• The input buffers and pull-ups are disabled on the shared GPIO/LED pins.

The following LED function definitions apply :

• Activity - The signal is pulsed active for 80mS to indicate transmit or receive activity on the port. The signal is

TABLE 16-1:

LED OPERATION AS A FUNCTION OF LED_FUN[2:0] = 000B - 011B

000b

001b

010b

011b

LED2

(GPIO2)

Link / Activity

100Link / Activity

Activity

LED1

(GPIO1)

Full-duplex / Collision

Link

LED0

(GPIO0)

Speed

10Link / Activity

Speed

Full-duplex / Collision

TABLE 16-2:

LED OPERATION AS A FUNCTION OF LED_FUN[2:0] = 100B - 111B

100b

101b

110b

111b

LED2

(GPIO2)

Activity

Reserved

LED1

(GPIO1)

10Link

LED0

(GPIO0)

100Link

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