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      1 /*
      2  * Author: Jon Trulson <jtrulson (at) ics.com>
      3  * Copyright (c) 2015 Intel Corporation.
      4  *
      5  * Permission is hereby granted, free of charge, to any person obtaining
      6  * a copy of this software and associated documentation files (the
      7  * "Software"), to deal in the Software without restriction, including
      8  * without limitation the rights to use, copy, modify, merge, publish,
      9  * distribute, sublicense, and/or sell copies of the Software, and to
     10  * permit persons to whom the Software is furnished to do so, subject to
     11  * the following conditions:
     12  *
     13  * The above copyright notice and this permission notice shall be
     14  * included in all copies or substantial portions of the Software.
     15  *
     16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
     17  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
     18  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
     19  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
     20  * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
     21  * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
     22  * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     23  */
     24 
     25 #include <iostream>
     26 #include <string>
     27 #include <stdexcept>
     28 
     29 #include "grovewfs.h"
     30 
     31 using namespace upm;
     32 using namespace std;
     33 
     34 GroveWFS::GroveWFS(int pin)
     35 {
     36   if ( !(m_gpio = mraa_gpio_init(pin)) )
     37     {
     38       throw std::invalid_argument(std::string(__FUNCTION__) +
     39                                   ": mraa_gpio_init() failed, invalid pin?");
     40       return;
     41     }
     42 
     43   mraa_gpio_dir(m_gpio, MRAA_GPIO_IN);
     44 
     45   initClock();
     46   m_flowCounter = 0;
     47   m_isrInstalled = false;
     48 }
     49 
     50 GroveWFS::~GroveWFS()
     51 {
     52   if (m_isrInstalled)
     53     stopFlowCounter();
     54 
     55   mraa_gpio_close(m_gpio);
     56 }
     57 
     58 void GroveWFS::initClock()
     59 {
     60   gettimeofday(&m_startTime, NULL);
     61 }
     62 
     63 uint32_t GroveWFS::getMillis()
     64 {
     65   struct timeval elapsed, now;
     66   uint32_t elapse;
     67 
     68   // get current time
     69   gettimeofday(&now, NULL);
     70 
     71   // compute the delta since m_startTime
     72   if( (elapsed.tv_usec = now.tv_usec - m_startTime.tv_usec) < 0 )
     73     {
     74       elapsed.tv_usec += 1000000;
     75       elapsed.tv_sec = now.tv_sec - m_startTime.tv_sec - 1;
     76     }
     77   else
     78     {
     79       elapsed.tv_sec = now.tv_sec - m_startTime.tv_sec;
     80     }
     81 
     82   elapse = (uint32_t)((elapsed.tv_sec * 1000) + (elapsed.tv_usec / 1000));
     83 
     84   // never return 0
     85   if (elapse == 0)
     86     elapse = 1;
     87 
     88   return elapse;
     89 }
     90 
     91 void GroveWFS::startFlowCounter()
     92 {
     93   initClock();
     94   // install our interrupt handler
     95   mraa_gpio_isr(m_gpio, MRAA_GPIO_EDGE_RISING,
     96                 &flowISR, this);
     97 
     98   m_isrInstalled = true;
     99 }
    100 
    101 void GroveWFS::stopFlowCounter()
    102 {
    103   // remove the interrupt handler
    104   mraa_gpio_isr_exit(m_gpio);
    105 
    106   m_isrInstalled = false;
    107 }
    108 
    109 void GroveWFS::flowISR(void *ctx)
    110 {
    111   upm::GroveWFS *This = (upm::GroveWFS *)ctx;
    112   This->m_flowCounter++;
    113 }
    114 
    115 float GroveWFS::flowRate()
    116 {
    117   uint32_t millis = getMillis();
    118   uint32_t flow = flowCounter();
    119 
    120   // 7.5 comes from the seeedstudio page, see the confusing datasheet :)
    121   float flowRate = (float(flow) * 7.5) / ((float(millis) / 1000.0) * 60.0);
    122 
    123   return flowRate;
    124 }
    125