mhz16: Initial implementation

This library implements support for the MHZ16 CO2 sensor.

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/mhz16/CMakeLists.txt

@@ -0,0 +1,5 @@
+set (libname "mhz16")
+set (libdescription "upm grove CO2 sensor")
+set (module_src ${libname}.cxx)
+set (module_h ${libname}.h)
+upm_module_init()

src/mhz16/jsupm_mhz16.i

@@ -0,0 +1,13 @@
+%module jsupm_mhz16
+%include "../upm.i"
+%include "cpointer.i"
+
+/* Send "int *" to JavaScript as intp */
+%pointer_functions(int, intp);
+%{
+    #include "mhz16.h"
+    speed_t int_B9600 = B9600;
+%}
+
+%include "mhz16.h"
+speed_t int_B9600 = B9600;

src/mhz16/mhz16.cxx

@@ -0,0 +1,219 @@
+/*
+ * 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 "mhz16.h"
+
+using namespace upm;
+using namespace std;
+
+static const int defaultDelay = 100;     // max wait time for read
+
+MHZ16::MHZ16(int uart)
+{
+  m_ttyFd = -1;
+
+  if ( !(m_uart = mraa_uart_init(uart)) )
+    {
+      cerr << __FUNCTION__ << ": mraa_uart_init() failed" << endl;
+      return;
+    }
+
+  // This requires a recent MRAA (1/2015)
+  char *devPath = mraa_uart_get_dev_path(m_uart);
+
+  if (!devPath)
+    {
+      cerr << __FUNCTION__ << ": mraa_uart_get_dev_path() failed" << endl;
+      return;
+    }
+
+  // now open the tty
+  if ( (m_ttyFd = open(devPath, O_RDWR)) == -1)
+    {
+      cerr << __FUNCTION__ << ": open of " << devPath << " failed: " 
+           << strerror(errno) << endl;
+      return;
+    }
+}
+
+MHZ16::~MHZ16()
+{
+  if (m_ttyFd != -1)
+    close(m_ttyFd);
+
+  mraa_deinit();
+}
+
+bool MHZ16::dataAvailable(unsigned int millis)
+{
+  if (m_ttyFd == -1)
+    return false;
+
+  struct timeval timeout;
+
+  // no waiting
+  timeout.tv_sec = 0;
+  timeout.tv_usec = millis * 1000;
+
+  int nfds;  
+  fd_set readfds;
+
+  FD_ZERO(&readfds);
+
+  FD_SET(m_ttyFd, &readfds);
+  
+  if (select(m_ttyFd + 1, &readfds, NULL, NULL, &timeout) > 0)
+    return true;                // data is ready
+  else
+    return false;
+}
+
+int MHZ16::readData(char *buffer, size_t len)
+{
+  if (m_ttyFd == -1)
+    return(-1);
+
+  if (!dataAvailable(defaultDelay))
+    return 0;               // timed out
+
+  int rv = read(m_ttyFd, buffer, len);
+
+  if (rv < 0)
+    cerr << __FUNCTION__ << ": read failed: " << strerror(errno) << endl;
+
+  return rv;
+}
+
+int MHZ16::writeData(char *buffer, size_t len)
+{
+  if (m_ttyFd == -1)
+    return(-1);
+
+  // first, flush any pending but unread input
+  tcflush(m_ttyFd, TCIFLUSH);
+
+  int rv = write(m_ttyFd, buffer, len);
+
+  if (rv < 0)
+    {
+      cerr << __FUNCTION__ << ": write failed: " << strerror(errno) << endl;
+      return rv;
+    }
+
+  tcdrain(m_ttyFd);
+
+  return rv;
+}
+
+bool MHZ16::setupTty(speed_t baud)
+{
+  if (m_ttyFd == -1)
+    return(false);
+  
+  struct termios termio;
+
+  // get current modes
+  tcgetattr(m_ttyFd, &termio);
+
+  // setup for a 'raw' mode.  81N, no echo or special character
+  // handling, such as flow control.
+  cfmakeraw(&termio);
+
+  // set our baud rates
+  cfsetispeed(&termio, baud);
+  cfsetospeed(&termio, baud);
+
+  // make it so
+  if (tcsetattr(m_ttyFd, TCSAFLUSH, &termio) < 0)
+    {
+      cerr << __FUNCTION__ << ": tcsetattr failed: " << strerror(errno) << endl;
+      return false;
+    }
+
+  return true;
+}
+
+bool MHZ16::verifyPacket(unsigned char *pkt)
+{
+  if (pkt[0] != 0xff || pkt[1] != 0x86)
+    {
+      cerr << __FUNCTION__ << ": Inavlid packet header." << endl;
+      return false;
+    }
+  
+  return true;
+}
+
+bool MHZ16::getData(int *gas, int *temp)
+{
+  // the query command
+  const unsigned char cmd[9] = 
+    {0xff, 0x01, 0x86, 0x00, 0x00, 0x00, 0x00, 0x00, 0x79};
+
+  writeData((char *)cmd, 9);
+
+  // wait up to one second for a response
+  if (!dataAvailable(1000))
+    {
+      cerr << __FUNCTION__ << ": Timed out waiting for response." << endl;
+      return false;
+    }
+
+  // read the packet
+  unsigned char packet[9];
+  int rv;
+
+  if ((rv = readData((char *)packet, 9)) != 9)
+    {
+      cerr << __FUNCTION__ << ": Invalid packet read, rv = " << rv 
+           << ", expected 9." << endl;
+      return false;
+    }
+  
+  if (!verifyPacket(packet))
+    {
+      cerr << __FUNCTION__ << ": Packet verify failed." << endl;
+      return false;
+    }
+
+  // pull out the data and return it.
+  *gas = (packet[2] << 8) | packet[3];
+  *temp = packet[4] - 40;
+
+  return true;
+}
+
+void MHZ16::calibrateZeroPoint()
+{
+  // the query command
+  const unsigned char cmd[9] = 
+    {0xff, 0x01, 0x87, 0x00, 0x00, 0x00, 0x00, 0x00, 0x78};
+
+  writeData((char *)cmd, 9);
+
+  // no response
+}
+

src/mhz16/mhz16.h

@@ -0,0 +1,161 @@
+/*
+ * 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 <string>
+#include <iostream>
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <termios.h>
+#include <sys/time.h>
+#include <sys/select.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include <mraa/uart.h>
+
+const int MHZ16_DEFAULT_UART = 0;
+
+// protocol start and end codes
+const uint8_t MHZ16_START = 0x7e;
+const uint8_t MHZ16_END   = 0x7e;
+
+namespace upm {
+    /**
+     * @brief UPM support for the MHZ16 Serial CO2 sensor
+     * @defgroup mhz16 libupm-mhz16
+     * @ingroup seeed serial gas
+     */
+
+    /**
+     * @sensor mhz16
+     * @library mhz16
+     * @name Grove CO2 sensor
+     * @category gaseous
+     * @manufacturer seeed
+     * @connection uart
+     *
+     * @brief C++ API support for the Grove CO2 sensor
+     *
+     * This class implements support for the Grove CO2 sensor.
+     *
+     * It's CO2 detection ranges from 0PPM to 2000PPM.  It requires a
+     * 2-3 minute warm up time before reporting valid data.
+     * 
+     * @snippet mhz16.cxx Interesting
+     */
+  class MHZ16 {
+  public:
+
+    
+    /**
+     * MHZ16 module constructor
+     *
+     * @param uart default uart to use (0 or 1)
+     */
+    MHZ16(int uart);
+
+    /**
+     * MHZ16 module Destructor
+     */
+    ~MHZ16();
+
+    /**
+     * Check to see if there is data available for reading
+     *
+     * @param millis number of milliseconds to wait, 0 means no wait.
+     * @return true if there is data available to be read
+     */
+    bool dataAvailable(unsigned int millis);
+
+    /**
+     * read any available data into a user-supplied buffer.  Note, the
+     * call will block until data is available to be read.  Use
+     * dataAvailable() to determine whether there is data available
+     * beforehand, to avoid blocking.
+     *
+     * @param buffer the buffer to hold the data read
+     * @param len the length of the buffer
+     * @return the number of bytes read
+     */
+    int readData(char *buffer, size_t len);
+
+    /**
+     * write the data in buffer to the device
+     *
+     * @param buffer the buffer to hold the data read
+     * @param len the length of the buffer
+     * @return the number of bytes written
+     */
+    int writeData(char *buffer, size_t len);
+
+    /**
+     * setup the proper tty i/o modes and the baudrate.  The default
+     * baud rate is 9600 (B9600).
+     *
+     * @param baud the desired baud rate.  
+     * @return true if successful
+     */
+    bool setupTty(speed_t baud=B9600);
+
+    /**
+     * verify the packet header and indicate it's validity
+     *
+     * @param pkt the packet to check
+     * @return true if valid checksum, false otherwise
+     */
+    bool verifyPacket(unsigned char *pkt);
+
+    /**
+     * Query the sensor and return gas (CO2) concentration and
+     * temperature data.
+     *
+     * @param gas the returned gas concentration
+     * @param temp the returned temperature in celsius
+     * @return true if successful
+     */
+    bool getData(int *gas, int *temp);
+
+    /**
+     * Set the zero point of the sensor
+     *
+     */
+    void calibrateZeroPoint();
+
+  protected:
+    int ttyFd() { return m_ttyFd; };
+    int setTtyFd(int fd) { m_ttyFd = fd; };
+
+  private:
+    mraa_uart_context m_uart;
+    int m_ttyFd;
+  };
+}
+
+

src/mhz16/pyupm_mhz16.i

@@ -0,0 +1,14 @@
+%module pyupm_mhz16
+%include "../upm.i"
+%include "cpointer.i"
+
+%feature("autodoc", "3");
+
+/* Send "int *" to JavaScript as intp */
+%pointer_functions(int, intp);
+%{
+    #include "mhz16.h"
+    speed_t int_B9600 = B9600;
+%}
+%include "mhz16.h"
+speed_t int_B9600 = B9600;