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 |