mg811: Initial implementation

This driver was developed on a DFRobot CO2 sensor based on the MG811:
http://www.dfrobot.com/index.php?route=product/product&product_id=1023

It seems to *require* very precise calibration at 400ppm and 1000ppm
to be accurate.  It also gets pretty hot (due to the heater) and
consumes significant current.

Signed-off-by: Jon Trulson <jtrulson@ics.com>
Signed-off-by: sisinty sasmita patra <sisinty.s.patra@intel.com>

examples/c++/CMakeLists.txt

@@ -134,6 +134,7 @@ add_executable (ak8975-example ak8975.cxx)
 add_executable (lsm9ds0-example lsm9ds0.cxx)
 add_executable (eboled-example eboled.cxx)
 add_executable (hyld9767-example hyld9767.cxx)
+add_executable (mg811-example mg811.cxx)
 
 include_directories (${PROJECT_SOURCE_DIR}/src/hmc5883l)
 include_directories (${PROJECT_SOURCE_DIR}/src/grove)
@@ -241,6 +242,7 @@ include_directories (${PROJECT_SOURCE_DIR}/src/hp20x)
 include_directories (${PROJECT_SOURCE_DIR}/src/pn532)
 include_directories (${PROJECT_SOURCE_DIR}/src/lsm9ds0)
 include_directories (${PROJECT_SOURCE_DIR}/src/hyld9767)
+include_directories (${PROJECT_SOURCE_DIR}/src/mg811)
 
 target_link_libraries (hmc5883l-example hmc5883l ${CMAKE_THREAD_LIBS_INIT})
 target_link_libraries (groveled-example grove ${CMAKE_THREAD_LIBS_INIT})
@@ -376,3 +378,4 @@ target_link_libraries (ak8975-example mpu9150 ${CMAKE_THREAD_LIBS_INIT})
 target_link_libraries (lsm9ds0-example lsm9ds0 ${CMAKE_THREAD_LIBS_INIT})
 target_link_libraries (eboled-example i2clcd ${CMAKE_THREAD_LIBS_INIT})
 target_link_libraries (hyld9767-example hyld9767 ${CMAKE_THREAD_LIBS_INIT})
+target_link_libraries (mg811-example mg811 ${CMAKE_THREAD_LIBS_INIT})

examples/c++/mg811.cxx

@@ -0,0 +1,68 @@
+/*
+ * 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 <unistd.h>
+#include <iostream>
+#include <signal.h>
+#include "mg811.h"
+
+using namespace std;
+
+bool shouldRun = true;
+
+#define MG811_AREF   5.0
+
+void sig_handler(int signo)
+{
+  if (signo == SIGINT)
+    shouldRun = false;
+}
+
+int main()
+{
+  signal(SIGINT, sig_handler);
+
+//! [Interesting]
+
+  // Instantiate an MG811 on analog pin A0, and digital pin D2 with an
+  // analog reference voltage of MG811_AREF (5.0)
+  upm::MG811 *sensor = new upm::MG811(0, 2, MG811_AREF);
+  
+  // Every tenth of a second, sample the sensor and output it's
+  // detected CO2 concentration in parts per million (ppm)
+
+  while (shouldRun)
+    {
+      cout << "CO2 concentration in PPM: " << sensor->ppm() << endl;
+      
+      usleep(100000);
+    }
+
+//! [Interesting]
+
+  cout << "Exiting" << endl;
+
+  delete sensor;
+  return 0;
+}

examples/javascript/mg811.js

@@ -0,0 +1,53 @@
+/*jslint node:true, vars:true, bitwise:true, unparam:true */
+/*jshint unused:true */
+
+/*
+ * 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.
+ */
+
+
+var sensorObj = require('jsupm_mg811');
+
+// Instantiate an MG811 on analog pin A0, and digital pin D2 with an
+// analog reference voltage of MG811_AREF (5.0)
+
+var sensor = new sensorObj.MG811(0, 2, 5.0);
+
+// Every tenth of a second, sample the sensor and output it's
+// detected CO2 concentration in parts per million (ppm)
+
+setInterval(function()
+{
+    console.log("CO2 concentration in PPM: " + sensor.ppm());
+}, 100);
+
+// exit on ^C
+process.on('SIGINT', function()
+{
+    sensor = null;
+    sensorObj.cleanUp();
+    sensorObj = null;
+    console.log("Exiting.");
+    process.exit(0);
+});
+

examples/python/mg811.py

@@ -0,0 +1,51 @@
+#!/usr/bin/python
+# 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.
+
+import time, sys, signal, atexit
+import pyupm_mg811 as sensorObj
+
+# Instantiate an MG811 on analog pin A0, and digital pin D2 with an
+# analog reference voltage of MG811_AREF (5.0)
+
+sensor = sensorObj.MG811(0, 2, 5.0)
+
+## Exit handlers ##
+# This function stops python from printing a stacktrace when you hit control-C
+def SIGINTHandler(signum, frame):
+	raise SystemExit
+
+# This function lets you run code on exit
+def exitHandler():
+	print "Exiting"
+	sys.exit(0)
+
+# Register exit handlers
+atexit.register(exitHandler)
+signal.signal(signal.SIGINT, SIGINTHandler)
+
+# Every tenth of a second, sample the sensor and output it's
+# detected CO2 concentration in parts per million (ppm)
+
+while (1):
+        print "CO2 concentration in PPM: ", sensor.ppm()
+	time.sleep(.1)

src/mg811/CMakeLists.txt

@@ -0,0 +1,5 @@
+set (libname "mg811")
+set (libdescription "upm DFRobot CO2 sensor")
+set (module_src ${libname}.cxx)
+set (module_h ${libname}.h)
+upm_module_init()

src/mg811/javaupm_mg811.i

@@ -0,0 +1,8 @@
+%module javaupm_mg811
+%include "../upm.i"
+
+%{
+    #include "mg811.h"
+%}
+
+%include "mg811.h"

src/mg811/jsupm_mg811.i

@@ -0,0 +1,8 @@
+%module jsupm_mg811
+%include "../upm.i"
+
+%{
+    #include "mg811.h"
+%}
+
+%include "mg811.h"

src/mg811/mg811.cxx

@@ -0,0 +1,94 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2015 Intel Corporation.
+ *
+ * Thanks to public domain code by Martin Liddament for some useful clues!
+ * http://www.veetech.org.uk/CO2_Monitor_Sketch_2_Operation.txt
+ * and sandbox electronics (http://sandboxelectronics.com/?p=147).
+ *
+ * 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 <math.h>
+#include "mg811.h"
+
+using namespace std;
+using namespace upm;
+
+// voltage gain of the DC amplifier
+static const float dcGain = 8.5;
+
+MG811::MG811(int pin, int dpin, float aref) :
+  m_aio(pin), m_gpio(dpin)
+{
+  m_aRes = m_aio.getBit();
+  m_aref = aref;
+
+  m_gpio.dir(mraa::DIR_IN);
+
+  // these are just placeholder values (coarsely measured during
+  // development), you should determine the appropriate values (in
+  // volts) for your environment at the specified concentrations.  Use
+  // the getReferenceVoltage() method to get these values at 400ppm
+  // and 1000ppm respectively.  Good luck.
+  setCalibration(0.5514, 0.370);
+}
+
+MG811::~MG811()
+{
+}
+
+float MG811::volts()
+{
+  int val = m_aio.read();
+
+  return(float(val) * (m_aref / float(1 << m_aRes)));
+}
+
+void MG811::setCalibration(float ppm400, float ppm1000)
+{
+  m_zeroPointValue = ppm400;
+  m_reactionValue = ppm1000;
+}
+
+float MG811::getReferenceVoltage()
+{
+  return (volts() / dcGain);
+}
+
+float MG811::ppm()
+{
+  static const float log400 = log10f(400);
+  static const float log1000 = log10f(1000);
+
+  float val = volts();
+
+  if ((val / dcGain) >= m_zeroPointValue)
+    return 0.0;
+  else
+    return powf(10.0, ((val/dcGain)-m_zeroPointValue) / 
+                      (m_reactionValue / (log400-log1000))+log400);
+}
+
+bool MG811::thresholdReached()
+{
+  return (m_gpio.read() ? true : false);
+}

src/mg811/mg811.h

@@ -0,0 +1,146 @@
+/*
+ * 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.
+ */
+#pragma once
+
+#include <iostream>
+#include <string>
+#include <mraa/aio.hpp>
+#include <mraa/gpio.hpp>
+
+namespace upm {
+  /**
+   * @brief DFRobot CO2 Sensor
+   * @defgroup mg811 libupm-mg811
+   * @ingroup dfrobot analog gas
+   */
+
+  /**
+   * @library mg811
+   * @sensor mg811
+   * @comname DFRobot CO2 Sensor
+   * @altname MG811
+   * @type gas
+   * @man dfrobot
+   * @web http://www.dfrobot.com/index.php?route=product/product&product_id=1023
+   * @con analog
+   *
+   * @brief API for the DFRobot CO2 Sensor
+   *
+   * This sensor returns an an analog voltage that falls as the
+   * concentration of CO2 increases.  It contains a heater that must
+   * be allowed to 'warm' up the sensor before measurements are stable
+   * (hours to days is the recommendation).  It requires that the MCU
+   * be powered from an external power supply (not USB) at 5v, since
+   * the heater will consume significant current.
+   *
+   * The sensor should be allowed to 'heat' up for some time before
+   * beginning use, typically a couple of hours minimum.  It also
+   * needs fairly precise calibration at 400ppm and 1000ppm to return
+   * meaningful results.
+   *
+   * The sensor also incorporates a potentiometer that can be adjusted
+   * to specific threshold.  Once that threshold is reached, an LED
+   * on the sensor will light, and the digital pin will be driven
+   * high.
+   *
+   * @snippet mg811.cxx Interesting
+   */
+
+  class MG811 {
+  public:
+
+    /**
+     * MG811 constructor
+     *
+     * @param pin Analog pin to use
+     * @param dpin Digital pin that indicates threshold
+     * @param aref Analog reference voltage; default is 5.0 V
+     */
+    MG811(int pin, int dpin, float aref=5.0);
+
+    /**
+     * MG811 destructor
+     */
+    ~MG811();
+
+    /**
+     * Return a cumputed reference voltage to be used in calibration.
+     * @return Computed reference voltage
+     */
+    float getReferenceVoltage();
+
+    /**
+     * Set calibration parameters.  You should measure the reference
+     * voltage you get when at CO2 concentrations of 400ppm (ambient)
+     * and 1000ppm using the getReferenceVoltage() method.  Then
+     * specify those voltages here for more accurate results.
+     *
+     * @param ppm400 The measured reference voltage at 400 ppm
+     * @param ppm40000 The measured reference voltage at 1000 ppm
+     */
+    void setCalibration(float ppm400, float ppm1000);
+
+    /**
+     * Returns the voltage detected on the analog pin
+     *
+     * @return The detected voltage
+     */
+    float volts();
+
+    /**
+     * Returns the computed CO2 concentration in ppm (Parts Per
+     * Million).  This method will return 0.0 if the reference voltage
+     * is greater than the ppm400 value.  Essentially, ppm values
+     * below 400 will be reported as 0.
+     *
+     * @return The computed CO2 concentration in ppm
+     */
+    float ppm();
+
+    /**
+     * Read the digital pin and return true if the set threshold has
+     * been reached or exceeded.  This threshold is set by adjusting
+     * the potentiometer on the sensor.
+     *
+     * @return true if the threshold has been reached, false otherwise
+     */
+    bool thresholdReached();
+
+  protected:
+    mraa::Aio m_aio;
+    mraa::Gpio m_gpio;
+
+    // calibration values
+    float m_zeroPointValue;
+    float m_reactionValue;
+
+    // ADC resolution
+    int m_aRes;
+
+  private:
+    float m_aref;
+  };
+}
+
+

src/mg811/pyupm_mg811.i

@@ -0,0 +1,9 @@
+%module pyupm_mg811
+%include "../upm.i"
+
+%feature("autodoc", "3");
+
+%include "mg811.h"
+%{
+    #include "mg811.h"
+%}