peripheral/libupm/src/grovewfs/grovewfs.cxx

/*
 * 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 <string>
#include <stdexcept>

#include "grovewfs.h"

using namespace upm;
using namespace std;

GroveWFS::GroveWFS(int pin)
{
  if ( !(m_gpio = mraa_gpio_init(pin)) )
    {
      throw std::invalid_argument(std::string(__FUNCTION__) +
                                  ": mraa_gpio_init() failed, invalid pin?");
      return;
    }

  mraa_gpio_dir(m_gpio, MRAA_GPIO_IN);

  initClock();
  m_flowCounter = 0;
  m_isrInstalled = false;
}

GroveWFS::~GroveWFS()
{
  if (m_isrInstalled)
    stopFlowCounter();

  mraa_gpio_close(m_gpio);
}

void GroveWFS::initClock()
{
  gettimeofday(&m_startTime, NULL);
}

uint32_t GroveWFS::getMillis()
{
  struct timeval elapsed, now;
  uint32_t elapse;

  // get current time
  gettimeofday(&now, NULL);

  // compute the delta since m_startTime
  if( (elapsed.tv_usec = now.tv_usec - m_startTime.tv_usec) < 0 ) 
    {
      elapsed.tv_usec += 1000000;
      elapsed.tv_sec = now.tv_sec - m_startTime.tv_sec - 1;
    } 
  else 
    {
      elapsed.tv_sec = now.tv_sec - m_startTime.tv_sec;
    }

  elapse = (uint32_t)((elapsed.tv_sec * 1000) + (elapsed.tv_usec / 1000));

  // never return 0
  if (elapse == 0)
    elapse = 1;

  return elapse;
}

void GroveWFS::startFlowCounter()
{
  initClock();
  // install our interrupt handler
  mraa_gpio_isr(m_gpio, MRAA_GPIO_EDGE_RISING, 
                &flowISR, this);

  m_isrInstalled = true;
}

void GroveWFS::stopFlowCounter()
{
  // remove the interrupt handler
  mraa_gpio_isr_exit(m_gpio);

  m_isrInstalled = false;
}

void GroveWFS::flowISR(void *ctx)
{
  upm::GroveWFS *This = (upm::GroveWFS *)ctx;
  This->m_flowCounter++;
}

float GroveWFS::flowRate()
{
  uint32_t millis = getMillis();
  uint32_t flow = flowCounter();
  
  // 7.5 comes from the seeedstudio page, see the confusing datasheet :)
  float flowRate = (float(flow) * 7.5) / ((float(millis) / 1000.0) * 60.0);

  return flowRate;
}