dfrorp: Initial implementation

This module implements support for the DFRobot Analog ORP
(Oxidation/Reduction Potential) Meter.

It requires 5.0 volts, but the more accurate the voltage specified (to
the constructor), the more accurate the meter (paraphrased from the
wiki).

Signed-off-by: Jon Trulson <jtrulson@ics.com>

examples/java/DFRORP_Example.java

@@ -0,0 +1,68 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2016 Intel Corporation.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+import upm_dfrorp.DFRORP;
+
+public class DFRORP_Example
+{
+    public static void main(String[] args) throws InterruptedException
+    {
+// ! [Interesting]
+
+        // Instantiate a DFRobot ORP sensor on analog pin A0 with an
+        // analog reference voltage of 5.0.
+        DFRORP sensor = new DFRORP(0, 5.0f);
+
+        // To calibrate:
+        //
+        // Disconnect the sensor probe (but leave the sensor interface
+        // board connected).  Then run one of the examples while
+        // holding down the 'calibrate' button on the device.  Read
+        // the ORP value reported (it should be fairly small).
+        //
+        // This value is what you should supply to
+        // setCalibrationOffset().  Then reconnect the probe to the
+        // interface board and you should be ready to go.
+        //
+        // DO NOT press the calibrate button on the interface board
+        // while the probe is attached or you can permanently damage
+        // the probe.
+        sensor.setCalibrationOffset(0.97f);
+
+        // Every second, update and print values
+        while (true)
+            {
+                sensor.update();
+
+                System.out.println("ORP: " +
+                                   sensor.getORP()
+                                   + " mV");
+
+                System.out.println();
+                Thread.sleep(1000);
+            }
+
+// ! [Interesting]
+    }
+}