1 /* 2 * Author: Zion Orent <sorent (at) ics.com> 3 * Copyright (c) 2014 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 #include <stddef.h> 29 #include <stdio.h> 30 #include <time.h> 31 #include <math.h> 32 #include <sys/sysinfo.h> 33 #include "ppd42ns.h" 34 35 using namespace upm; 36 37 PPD42NS::PPD42NS(int pin) 38 { 39 if ( !(m_gpio = mraa_gpio_init(pin)) ) 40 { 41 throw std::invalid_argument(std::string(__FUNCTION__) + 42 ": mraa_gpio_init() failed, invalid pin?"); 43 return; 44 } 45 46 mraa_gpio_dir(m_gpio, MRAA_GPIO_IN); 47 } 48 49 PPD42NS::~PPD42NS() 50 { 51 mraa_gpio_close(m_gpio); 52 } 53 54 dustData PPD42NS::getData() 55 { 56 dustData data; 57 struct timespec printData_start={0,0}; 58 struct timespec printData_now={0,0}; 59 clock_gettime(CLOCK_MONOTONIC, &printData_start); 60 clock_gettime(CLOCK_MONOTONIC, &printData_now); 61 double low_pulse_occupancy = 0; 62 double pulse_check_time = 30; 63 64 // Keep reading dust data until 30 seconds have passed 65 double start_time, end_time; 66 while (m_timediff(printData_start, printData_now) < pulse_check_time) 67 { 68 start_time = m_timediff(printData_start, printData_now); 69 end_time = pulse_check_time - start_time; 70 low_pulse_occupancy += pulseIn_polyfill(0, end_time); 71 clock_gettime(CLOCK_MONOTONIC, &printData_now); 72 } 73 74 // Store dust data 75 double ratio = low_pulse_occupancy / (pulse_check_time * 1000 * 10.0); // Integer percentage 0=>100 76 double concentration = (1.1 * pow(ratio,3)) - (3.8 * pow(ratio, 2)) + (520 * ratio) + 0.62; // using spec sheet curve 77 data.lowPulseOccupancy = (int)low_pulse_occupancy; 78 data.ratio = ratio; 79 data.concentration = concentration; 80 81 return data; 82 } 83 84 85 // Mimicking Arduino's pulseIn function 86 // return how long it takes a pin to go from HIGH to LOW or LOW to HIGH 87 double PPD42NS::pulseIn_polyfill(bool high_low_value, double end_time) 88 { 89 struct timespec pulseIn_start={0,0}; 90 struct timespec pulseIn_now={0,0}; 91 struct timespec pulsetime_start={0,0}; 92 struct timespec pulsetime_end={0,0}; 93 94 int pin_val = 5; // some non-zero, non-1 number 95 bool started_timing = false; 96 bool ended_timing = false; 97 clock_gettime(CLOCK_MONOTONIC, &pulseIn_start); 98 99 // run through this loop until either: 100 // a) we detect a change in pulse 101 // b) we've hit 30 seconds 102 while (!ended_timing && (m_timediff(pulseIn_start, pulseIn_now) < end_time)) 103 { 104 pin_val = (bool)mraa_gpio_read(m_gpio); 105 if (pin_val == high_low_value && !started_timing) 106 { 107 clock_gettime(CLOCK_MONOTONIC, &pulsetime_start); 108 started_timing = true; 109 //std::cout << "Started counting pulse change" << std::endl; 110 usleep(50); 111 } 112 else if (started_timing && pin_val != high_low_value) 113 { 114 clock_gettime(CLOCK_MONOTONIC, &pulsetime_end); 115 ended_timing = true; 116 //std::cout << "Ended counting pulse change" << (m_timediff(pulseIn_start, pulseIn_now)) << std::endl; 117 } 118 else 119 usleep(50); 120 clock_gettime(CLOCK_MONOTONIC, &pulseIn_now); 121 } 122 123 double low_pulse_occupancy = 0; 124 125 // if we ended due to detecting a pulse change and not due to hitting 30 seconds 126 if (started_timing && ended_timing) 127 low_pulse_occupancy = m_timediff(pulsetime_start, pulsetime_end); 128 //std::cout << "Low pulse occupancy is " << low_pulse_occupancy << " seconds" << std::endl; 129 130 return (low_pulse_occupancy * 1000000); // convert to microseconds 131 } 132 133 double PPD42NS::m_timediff(timespec time1, timespec time2) 134 { 135 return ((double)time2.tv_sec + 1.0e-9*time2.tv_nsec) - 136 ((double)time1.tv_sec + 1.0e-9*time1.tv_nsec); 137 } 138
