Method LED

java/libraries/io/src/processing/io/LED.java:52–103

Opens a LED device @param dev device name @see list @webref

(String dev)

   *  @webref
   */
  public LED(String dev) {
    NativeInterface.loadLibrary();
    this.dev = dev;

    if (NativeInterface.isSimulated()) {
      return;
    }

    // read maximum brightness
    try {
      Path path = Paths.get("/sys/class/leds/" + dev + "/max_brightness");
      String tmp = new String(Files.readAllBytes(path));
      maxBrightness = Integer.parseInt(tmp.trim());
    } catch (Exception e) {
      System.err.println(e.getMessage());
      throw new RuntimeException("Unable to read maximum brightness");
    }

    // read current trigger setting to be able to restore it later
    try {
      Path path = Paths.get("/sys/class/leds/" + dev + "/trigger");
      String tmp = new String(Files.readAllBytes(path));
      int start = tmp.indexOf('[');
      int end = tmp.indexOf(']', start);
      if (start != -1 && end != -1) {
        prevTrigger = tmp.substring(start+1, end);
      }
    } catch (Exception e) {
      System.err.println(e.getMessage());
      throw new RuntimeException("Unable to read trigger setting");
    }

    // read current brightness to be able to restore it later
    try {
      Path path = Paths.get("/sys/class/leds/" + dev + "/brightness");
      String tmp = new String(Files.readAllBytes(path));
      prevBrightness = Integer.parseInt(tmp.trim());
    } catch (Exception e) {
      System.err.println(e.getMessage());
      throw new RuntimeException("Unable to read current brightness");
    }

    // disable trigger
    String fn = "/sys/class/leds/" + dev + "/trigger";
    int ret = NativeInterface.writeFile(fn, "none");
    if (ret < 0) {
      if (ret == -13) {     // EACCES
        System.err.println("You might need to install a custom udev rule to allow regular users to modify /sys/class/leds/*.");
      }
      throw new RuntimeException(NativeInterface.getError(ret));
    }
  }


  /**