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/javascript/dfrorp.js

@@ -0,0 +1,70 @@
+/*jslint node:true, vars:true, bitwise:true, unparam:true */
+/*jshint unused:true */
+
+/*
+ * 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.
+ */
+
+var sensorObj = require('jsupm_dfrorp');
+
+// Instantiate a DFRobot ORP sensor on analog pin A0 with an analog
+// reference voltage of 5.0.
+var sensor = new sensorObj.DFRORP(0, 5.0);
+
+// 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(0.97);
+
+// Every second, update and print values
+setInterval(function()
+{
+    sensor.update();
+
+    console.log("ORP: "
+                + sensor.getORP()
+                + " mV");
+
+    console.log();
+
+}, 1000);
+
+// exit on ^C
+process.on('SIGINT', function()
+{
+    sensor = null;
+    sensorObj.cleanUp();
+    sensorObj = null;
+    console.log("Exiting.");
+    process.exit(0);
+});