LEDs

The Duckbill is equipped with a two-color status LED at the bottom side. Each color of the LED is wired to a dedicated GPIO pin of the CPU. As usual in Linux, both colors are modelled as individual LED in the BSP.

During boot process, U-Boot switches the red LED on shortly to indicate that a software component is running at all. When linux kernel takes over, it flashes the green LED like a heartbeat, to indicate that the kernel is still alive and running.

Attribute	Status LED
Color	red	green
Linux Device	/sys/class/leds/duckbill:red:status	/sys/class/leds/duckbill:green:status
Default trigger	none	heartbeat

The following table lists various device states.

Status LED		Duration of this state	Status / possible solution
red	green
off	off	persistent	Device is powered off, attach power supply
on	off	< 10s	U-Boot is running and loading Linux
on	flashing	< 25s	Linux kernel is booting
on	off	persistent	U-Boot could not start Linux, attach Debug UART to see U-Boot’s error message; check U-Boot’s image and/or fdt_file environment settings and ensure, that these two files are present in the root filesystem below /boot
off	flashing	persistent	Linux system is running
on	flashing	persistent	Linux system is running, but errors during initialization