【树莓派】板载LED控制

Rehtt

January 10, 2022

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树莓派笔记

# 0x00

有两种方式控制树莓派板载的LED

# 0x01 开机后方案

> 重启会失效

控制板载灯的有以下文件：

```sh
# 状态灯
/sys/class/leds/led0/brightness
/sys/class/leds/led0/trigger

# 电源灯
/sys/class/leds/led1/brightness
/sys/class/leds/led1/trigger
```

就可以控制状态灯和电源灯

其中`brightness`文件是亮度控制，接受范围是0~255，数字越大越亮，默认是255

`trigger`文件是控制灯的模式，可以通过`cat /sys/class/leds/led0/trigger`读取模式，我的系统是树莓派爱好者基地提供的`Debian-Pi-Aarch64`，其中模式共有：

> [none] usb-gadget usb-host rc-feedback kbd-scrolllock kbd-numlock kbd-capslock kbd-kanalock kbd-shiftlock kbd-altgrlock kbd-ctrllock kbd-altlock kbd-shiftllock kbd-shiftrlock kbd-ctrlllock kbd-ctrlrlock timer oneshot heartbeat backlight gpio cpu cpu0 cpu1 cpu2 cpu3 default-on input panic actpwr mmc1 mmc0 rfkill-any rfkill-none rfkill0 bluetooth-power hci0-power rfkill1

默认下状态灯的模式是`cpu`，电源灯的模式是`hci0-power`

将模式设为`none`就是关闭灯

示例：

```sh
# 关闭状态灯
echo none | sudo tee /sys/class/leds/led0/trigger

# 调节电源灯亮度
echo 125 | sudo tee /sys/class/leds/led1/brightness
```

# 0x02 开机前方案

如果想要不重启失效，就需要通过修改`/boot/config.txt`文件来实现。

首先官方文档有说明：

```
  # 状态灯
      act_led_trigger         Choose which activity the LED tracks.
                                Use "heartbeat" for a nice load indicator.
                                (default "mmc")
        act_led_activelow       Set to "on" to invert the sense of the LED
                                (default "off")
                                N.B. For Pi 3B, 3B+, 3A+ and 4B, use the act-led
                                overlay.
        act_led_gpio            Set which GPIO to use for the activity LED
                                (in case you want to connect it to an external
                                device)
                                (default "16" on a non-Plus board, "47" on a
                                Plus or Pi 2)
                                N.B. For Pi 3B, 3B+, 3A+ and 4B, use the act-led
                                overlay
  # 电源灯
        pwr_led_trigger
        pwr_led_activelow
        pwr_led_gpio
                                As for act_led_*, but using the PWR LED.
                                Not available on Model A/B boards.
  # 网络灯
        eth_led0                Set mode of LED0 (usually orange) (default
                                "1"). The legal values are:
                                0=link/activity          1=link1000/activity
                                2=link100/activity       3=link10/activity
                                4=link100/1000/activity  5=link10/1000/activity
                                6=link10/100/activity    14=off    15=on
        eth_led1                Set mode of LED1 (usually green) (default
                                "6"). See eth_led0 for legal values.
```

只需要在`/boot/config.txt`中添加相应的设置就可以实现

示例，关闭所有灯：

```
#设置状态灯为none模式
dtparam=act_led_trigger=none

#设置电源灯为none模式
dtparam=pwr_led_trigger=none

#设置网口灯为off
dtparam=eth_led0=14
dtparam=eth_led1=14
```

Last modification：January 12, 2022