Method digitalRead

java/libraries/io/src/processing/io/GPIO.java:199–223

Returns the value of an input pin, which is either GPIO.HIGH (1) or GPIO.LOW (0) You need to set the pin to input by calling pinMode() before calling this function. @param pin GPIO pin @return GPIO.HIGH (1) or GPIO.LOW (0) @see pinMode @see digit

(int pin)

   *  @webBrief Returns the value of an input pin
   */
  public static int digitalRead(int pin) {
    checkValidPin(pin);

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

    String fn = String.format("/sys/class/gpio/gpio%d/value", pin);
    byte in[] = new byte[2];
    int ret = NativeInterface.readFile(fn, in);
    if (ret < 0) {
      throw new RuntimeException(NativeInterface.getError(ret));
    } else if (1 <= ret && in[0] == '0') {
      return LOW;
    } else if (1 <= ret && in[0] == '1') {
      return HIGH;
    } else {
      System.err.print("Read " + ret + " bytes");
      if (0 < ret) {
        System.err.format(", first byte is 0x%02x" + in[0]);
      }
      System.err.println();
      throw new RuntimeException("Unexpected value");
    }
  }


  /**