| /* |
| * 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.h" |
| |
| 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); |
| } |