ad8232: Initial Implementation

This driver implements support for the Sparkfun Single Lead Heart Rate
Monitor, based on the AD8232 chip.

It simply outputs ADC data that needs to be sent somewhere for
plotting.  The Sparkfun page has some suggestions.

Alternatively, if you have an oscilliscope that supports a 'Roll'
mode, you can get an EKG-like display by measuring the OUT pin.

https://www.sparkfun.com/products/12650

Signed-off-by: Jon Trulson <jtrulson@ics.com>
Signed-off-by: Mihai Tudor Panu <mihai.tudor.panu@intel.com>

src/ad8232/ad8232.cxx

@@ -0,0 +1,52 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2015 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.
+ */
+
+#include <iostream>
+
+#include "ad8232.h"
+
+using namespace upm;
+using namespace std;
+
+AD8232::AD8232(int loPlus, int loMinus, int output, float aref) :
+  m_gpioLOPlus(loPlus), m_gpioLOMinus(loMinus), m_aioOUT(output)
+{
+  m_gpioLOPlus.dir(mraa::DIR_IN);
+  m_gpioLOMinus.dir(mraa::DIR_IN);
+  
+  m_aref = aref;
+  m_ares = (1 << m_aioOUT.getBit());
+}
+
+AD8232::~AD8232()
+{
+}
+
+int AD8232::value()
+{
+  if (m_gpioLOPlus.read() || m_gpioLOMinus.read())
+    return 0;
+  else
+    return m_aioOUT.read();
+}