🛠 LEDs du Lichee RV Dock : LED verte et RGB WS2812 pilotée par le LEDC du D1

Objectives

The Lichee RV Dock has TWO controllable LEDs under mainline Linux: the module's green "status" LED (pin PC1, standard LED class driver) and the Dock's RGB WS2812 (NeoPixel) LED on pin PC0 — a rare feature, it is driven by the D1's hardware LEDC peripheral, declared in the mainline device tree as a multicolor LED (multicolor class), without bit-banging. This tutorial introduces you to /sys/class/leds, triggers (timer, heartbeat), and the multicolor API multi_intensity.

Hardware

• Lichee RV Dock running a mainline image (Buildroot sipeed_lichee_rv_dock, Ubuntu 24.04 RISC-V, or Armbian D1) — kernel ≥ 6.3 for the board's device tree (merged in v6.3), and a subsequent WS2812/LEDC patch (commit f8ad8bbb8827) required for the RGB LED
• No external wiring: both LEDs are onboard

Complete code

# 1) Lister les LED visibles par le noyau
ls /sys/class/leds/
#   mainline : « green:status » (PC1, module) + une LED multicolore « status » (PC0, WS2812)

# 2) LED verte PC1 : trigger timer (clignotement 1 Hz)
echo timer | sudo tee '/sys/class/leds/green:status/trigger'
#   rythme cardiaque :
echo heartbeat | sudo tee '/sys/class/leds/green:status/trigger'
#   contrôle manuel :
echo none | sudo tee '/sys/class/leds/green:status/trigger'
echo 1 | sudo tee '/sys/class/leds/green:status/brightness'
echo 0 | sudo tee '/sys/class/leds/green:status/brightness'

# 3) RGB WS2812 (PC0) via le LEDC — LED multicolore, canaux R G B 0-255
RGB=$(ls -d /sys/class/leds/*status/multi_intensity 2>/dev/null | head -1)
echo "255 0 0"   | sudo tee "$RGB"     # rouge
echo "0 255 128" | sudo tee "$RGB"     # vert menthe
echo 64 | sudo tee "$(dirname $RGB)/brightness"   # luminosité globale

# 4) Petit script d'ambiance
while :; do for c in "255 0 0" "0 255 0" "0 0 255"; do
  echo "$c" | sudo tee "$RGB" >/dev/null; sleep 1; done; done

Expected verification

ls /sys/class/leds/ lists at least the green LED green:status and, with a sufficiently recent kernel, a multicolor device *::status containing multi_intensity. The timer trigger makes the green LED blink at 1 Hz; echo 1/0 to brightness visibly turns it on and off. The Dock's WS2812 actually changes color with multi_intensity (R G B separated by spaces) — if the multicolor device is missing, your kernel does not yet have the Dock's LEDC node. The cat of trigger shows the active value in brackets.

Common errors

• Forgetting to escape the colon in the name: in the shell, put the path in quotes ('/sys/class/leds/green:status/trigger') or use Tab completion.
• echo 1 > brightness without sudo: the redirection is performed by the shell without privilege escalation; use sudo tee.
• Looking for the WS2812 under a classic "led0" name: it is a MULTICOLOR LED (multi_intensity, multi_led), not a single-channel LED; older kernels sometimes expose it as a single-color LED.
• Testing under Tina Linux (vendor OpenWrt image): LED names there differ completely from mainline; refer to the Sipeed wiki on the vendor side.
• Confusing it with an external WS2812 strip: here the LEDC drives the onboard LED PC0; for an external strip, you need the leds-ax20000/pwm driver depending on the kernel.