LAN8804D datasheet(49/89 Pages) MICROCHIP

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LAN8804D

DS00003591K-page 49

5.16.2

GPIO INTERRUPTS

Each GPIO provides the ability to trigger a unique GPIO interrupt in the GPIO Interrupt Status Registers. Reading the

GPIO Interrupt Status Registers provides the current status of all GPIO interrupts. Each interrupt is enabled by setting

the corresponding bit in the GPIO Interrupt Enable Registers. The GPIO Controller aggregates the enabled interrupt

values into an internal signal that is sent to the main interrupt logic and is reflected via the GPIO Interrupt bit in the Chip-

level Interrupt Status register.

Bits in the GPIO Interrupt Status Registers are set by the interrupt events regardless of the value of the corresponding

bits in the GPIO Interrupt Enable Registers.

Each GPIO interrupt polarity can be set individually via the GPIO Interrupt Polarity Registers. When the Interrupt Polarity

bit is set to ‘1’, a high logic level on the GPIO pin will set the corresponding interrupt bit in the GPIO Interrupt Status

Registers. When the Interrupt Polarity bit is set to ‘0’, a low logic level on the GPIO pin will set the corresponding interrupt

bit in the GPIO Interrupt Status Registers.

5.16.3

GPIO TIMING

For GPIO timing information, refer to the following Section 6.6, "AC Specifications" sub-sections:

• GPIO Timing

• GPIO SOF Detection Timing

5.17

LEDs

The device provides eight programmable LEDs, two per port (PORT[0:3]LED[1:2]), which are configurable to support

multiple LED modes. The LED mode is configured by the LED_MODE configuration strap as well as port-specific

instances of the LED Control Register 1 and 2. All eight LEDs are configured with identical behavior via the LED_MODE

configuration strap. Port-specific LED configuration can be accomplished via the LED Control Register 1 and 2. The

supported LED modes are:

• Individual-LED Mode (LED Control Register 1, bit[6] (KSZ0931 LED mode) = ‘1’, LED_MODE pulled-up)

• Tri-color-LED Mode (LED Control Register 1, bit[6] (KSZ0931 LED mode) = ‘1’, LED_MODE pulled-down)

• Enhanced LED Mode (LED Control Register 1, bit[6] (KSZ0931 LED mode) = ‘0’, LED_MODE unused)

To use LEDs, they must be enabled as GPIOs and GPIO Alternate Functions. The GPIOs must be configured as Out-

puts, and the proper output driver type selected (open-drain or push-pull). If open-drain type is selected, the output driver

will automatically choose between open-source and open-drain based on LED polarity.

The PORT[3:0]_LED[2:1]_POL configuration straps set the default polarity of the LED pins. Refer to Section 3.3.5, "LED

Polarity (PORT[3:0]_LED[2:1]_POL)" for additional LED polarity information. Refer to Section 3.3.4, "LED Mode Select

(LED_MODE)" for additional LED_MODE information.

Note:

Upon reset, GPIOs that were outputs may generate an active interrupt status as the system settles—typi-

cally when a low GPIO pin slowly rises due to the internal pull-up. The interrupt status bits within the GPIO

Interrupt Status Registers must be cleared as part of the device initialization software routine.

Note:

Coma mode disables all LED functions. When the Coma mode input transitions from low to high, LED func-

tions begin normal operation. Refer to Section 5.18, "Coma Mode" for additional information.

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