grovevdiv: Initial implementation

This module implements support for the Grove Voltage Divider.
jrvandr: Removed unecessary mraa_init() from grovevdiv.cxx

Signed-off-by: Jon Trulson <jtrulson@ics.com>
Signed-off-by: Zion Orent <zorent@ics.com>
Signed-off-by: John Van Drasek <john.r.van.drasek@intel.com>

src/grovevdiv/grovevdiv.h

@@ -0,0 +1,87 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2014 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.
+ */
+#pragma once
+
+#include <string>
+#include <iostream>
+#include <stdint.h>
+#include <mraa/aio.h>
+
+// ref voltage in millivolts
+#define GROVEVDIV_VREF  4980
+
+// default ADC resolution. 
+#define GROVEVDIV_ADC_RES 1024
+
+namespace upm {
+
+  /**
+   * @brief C++ API for the Grove Voltage Divider Sensor
+   *
+   * UPM module for the Grove Voltage Divider Sensor
+   *
+   * @ingroup grove analog
+   * @snippet grovevdiv.cxx Interesting
+   */
+  class GroveVDiv {
+  public:
+    /**
+     * Grove Voltage Divider sensor constructor
+     *
+     * @param pin analog pin to use
+     */
+    GroveVDiv(int pin);
+
+    /**
+     * Grove Voltage Divider Destructor
+     */
+    ~GroveVDiv();
+
+    /**
+     * Get the conversion value from the sensor
+     *
+     * @param samples specifies how many samples to average over
+     * @return the averaged ADC conversion value
+     */
+    unsigned int value(unsigned int samples);
+
+    /**
+     * Compute the measured voltage
+     *
+     * @param gain gain switch, either 3 or 10 for grove
+     * @param val measured voltage (from value())
+     * @param vref reference voltage in millivolts
+     * @param res ADC resolution
+     *
+     * @return the measured voltage
+     */
+    float computedValue(uint8_t gain, uint16_t val, int vref=GROVEVDIV_VREF, 
+                        int res=GROVEVDIV_ADC_RES);
+
+  private:
+    mraa_aio_context m_aio;
+  };
+}
+
+