LED

A light-emitting diode (LED) is a semiconductor device that converts electrical energy into light energy. The Rhino Pi-A1 features 4 onboard tricolor LED indicators (led0 ~ led3), each containing three color channels: red, green, and blue. They can be used for system status indication or user-defined display.

Preparation

• Rhino Pi-A1
• Open-source tool: gpiod

sudo apt update
sudo apt install gpiod libgpiod2 libgpiod-dev

Testing

Android: LED Control

aidlux@aidlux:~$ sudo gpioinfo /dev/gpiochip0 | grep led
        line  27:      unnamed "led2_green"  output  active-high [used]
        line  44:      unnamed  "led2_blue"  output  active-high [used]
        line  46:      unnamed   "led3_red"  output  active-high [used]
        line 108:      unnamed   "led2_red"  output  active-high [used]
        line 112:      unnamed  "led1_blue"  output  active-high [used]
        line 118:      unnamed "led0_green"  output  active-high [used]
        line 122:      unnamed "led1_green"  output  active-high [used]
        line 135:      unnamed  "led3_blue"  output  active-high [used]

# Turn on LED3 red
and -s 'echo 1 > /sys/class/new_leds/led3_red/value'
# Turn off LED3 red
and -s 'echo 0 > /sys/class/new_leds/led3_red/value'
# Note: led3_green is already occupied by the system internally, so the LED on/off cannot be controlled by changing led3_green/value

Ubuntu: LED Control

aidlux@aidlux:~$ sudo gpioinfo /dev/gpiochip3 | grep led
        line  27:      unnamed "led2_green"  output  active-high [used]
        line  44:      unnamed  "led2_blue"  output  active-high [used]
        line  46:      unnamed   "led3_red"  output  active-high [used]
        line 108:      unnamed   "led2_red"  output  active-high [used]
        line 110:      unnamed   "led0_red"  output  active-high [used]
        line 112:      unnamed  "led1_blue"  output  active-high [used]
        line 118:      unnamed "led0_green"  output  active-high [used]
        line 122:      unnamed "led1_green"  output  active-high [used]
        line 135:      unnamed  "led3_blue"  output  active-high [used]
        line 142:      unnamed "led3_green"  output  active-high [used]

# Execute the following commands to control the LEDs
sudo su
cd /sys/class/gpio_userspace
# Turn on LED3 red
echo 1 > led3_red/value 
# Turn off LED3 red
echo 0 > led3_red/value 
# Note: led3_green is already occupied by the system internally, so the LED on/off cannot be controlled by changing led3_green/value