1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
|
/*
* Author: Zion Orent <sorent@ics.com>
* Copyright (c) 2014 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 <stddef.h>
#include <stdio.h>
#include <time.h>
#include <math.h>
#include <sys/sysinfo.h>
#include "ppd42ns.hpp"
using namespace upm;
PPD42NS::PPD42NS(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);
}
PPD42NS::~PPD42NS()
{
mraa_gpio_close(m_gpio);
}
dustData PPD42NS::getData()
{
dustData data;
struct timespec printData_start={0,0};
struct timespec printData_now={0,0};
clock_gettime(CLOCK_MONOTONIC, &printData_start);
clock_gettime(CLOCK_MONOTONIC, &printData_now);
double low_pulse_occupancy = 0;
double pulse_check_time = 30;
// Keep reading dust data until 30 seconds have passed
double start_time, end_time;
while (m_timediff(printData_start, printData_now) < pulse_check_time)
{
start_time = m_timediff(printData_start, printData_now);
end_time = pulse_check_time - start_time;
low_pulse_occupancy += pulseIn_polyfill(0, end_time);
clock_gettime(CLOCK_MONOTONIC, &printData_now);
}
// Store dust data
double ratio = low_pulse_occupancy / (pulse_check_time * 1000 * 10.0); // Integer percentage 0=>100
double concentration = (1.1 * pow(ratio,3)) - (3.8 * pow(ratio, 2)) + (520 * ratio) + 0.62; // using spec sheet curve
data.lowPulseOccupancy = (int)low_pulse_occupancy;
data.ratio = ratio;
data.concentration = concentration;
return data;
}
// Mimicking Arduino's pulseIn function
// return how long it takes a pin to go from HIGH to LOW or LOW to HIGH
double PPD42NS::pulseIn_polyfill(bool high_low_value, double end_time)
{
struct timespec pulseIn_start={0,0};
struct timespec pulseIn_now={0,0};
struct timespec pulsetime_start={0,0};
struct timespec pulsetime_end={0,0};
int pin_val = 5; // some non-zero, non-1 number
bool started_timing = false;
bool ended_timing = false;
clock_gettime(CLOCK_MONOTONIC, &pulseIn_start);
// run through this loop until either:
// a) we detect a change in pulse
// b) we've hit 30 seconds
while (!ended_timing && (m_timediff(pulseIn_start, pulseIn_now) < end_time))
{
pin_val = (bool)mraa_gpio_read(m_gpio);
if (pin_val == high_low_value && !started_timing)
{
clock_gettime(CLOCK_MONOTONIC, &pulsetime_start);
started_timing = true;
//std::cout << "Started counting pulse change" << std::endl;
usleep(50);
}
else if (started_timing && pin_val != high_low_value)
{
clock_gettime(CLOCK_MONOTONIC, &pulsetime_end);
ended_timing = true;
//std::cout << "Ended counting pulse change" << (m_timediff(pulseIn_start, pulseIn_now)) << std::endl;
}
else
usleep(50);
clock_gettime(CLOCK_MONOTONIC, &pulseIn_now);
}
double low_pulse_occupancy = 0;
// if we ended due to detecting a pulse change and not due to hitting 30 seconds
if (started_timing && ended_timing)
low_pulse_occupancy = m_timediff(pulsetime_start, pulsetime_end);
//std::cout << "Low pulse occupancy is " << low_pulse_occupancy << " seconds" << std::endl;
return (low_pulse_occupancy * 1000000); // convert to microseconds
}
double PPD42NS::m_timediff(timespec time1, timespec time2)
{
return ((double)time2.tv_sec + 1.0e-9*time2.tv_nsec) -
((double)time1.tv_sec + 1.0e-9*time1.tv_nsec);
}
|
