Method releasePin

java/libraries/io/src/processing/io/GPIO.java:508–526

Gives ownership of a pin back to the operating system Without calling this function, the pin will remain in the current state even after the sketch has been closed. @param pin GPIO pin @see pinMode @webref GPIO @webBrief Gives ownership of a pin back to the operating system

(int pin)

   *  @webBrief Gives ownership of a pin back to the operating system
   */
  public static void releasePin(int pin) {
    checkValidPin(pin);

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

    String fn = "/sys/class/gpio/unexport";
    int ret = NativeInterface.writeFile(fn, Integer.toString(pin));
    if (ret < 0) {
      if (ret == -2) {    // ENOENT
        System.err.println("Make sure your kernel is compiled with GPIO_SYSFS enabled");
      }
      // EINVAL is returned when trying to unexport pins that weren't exported to begin with, ignore this case
      if (ret != -22) {
        throw new RuntimeException(NativeInterface.getError(ret));
      }
    }
  }


  /**