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AQI: Adding ugm3 calculation to ppd42ns and aqi calculation to upm_utilities
Contributions by: Rex Tsai <rex.cc.tsai@gmail.com> Signed-off-by: Abhishek Malik <abhishek.malik@intel.com>
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@ -1,5 +1,7 @@
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/*
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* Author: Jon Trulson <jtrulson@ics.com>
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* Contributions: Rex Tsai <rex.cc.tsai@gmail.com>
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* Abhishek Malik <abhishek.malik@intel.com>
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* Copyright (c) 2016 Intel Corporation.
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*
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* Rewritten Based on original C++ driver written by:
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@ -39,6 +41,7 @@
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// from LOW to HIGH
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static uint32_t ppd42ns_pulse_in(const ppd42ns_context dev,
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bool high_low_value);
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double pcs2ugm3 (double concentration_pcs);
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ppd42ns_context ppd42ns_init(int pin)
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{
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@ -112,6 +115,8 @@ ppd42ns_dust_data ppd42ns_get_data(const ppd42ns_context dev)
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data.lowPulseOccupancy = low_pulse_occupancy;
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data.ratio = ratio;
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data.concentration = concentration;
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data.ugm3 = pcs2ugm3(data.concentration);
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data.aqi = upm_ugm3_to_aqi(data.ugm3);
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return data;
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}
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@ -165,3 +170,26 @@ static uint32_t ppd42ns_pulse_in(const ppd42ns_context dev,
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return total_pulse_time;
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}
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// Assumes density, shape, and size of dust to estimate mass concentration from particle count.
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//
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// This method was described in a 2009 paper
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// Preliminary Screening System for Ambient Air Quality in Southeast Philadelphia by Uva, M., Falcone, R., McClellan, A., and Ostapowicz, E.
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// https://www.yumpu.com/en/document/view/31692906/preliminary-screening-system-for-ambient-air-quality-in-southeast-
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//
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// This method does not use the correction factors, based on the presence of humidity and rain in the paper.
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//
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// convert from particles/0.01 ft3 to µg/m3
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double pcs2ugm3 (double concentration_pcs)
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{
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double pi = 3.14159;
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// All particles are spherical, with a density of 1.65E12 µg/m3
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double density = 1.65 * pow (10, 12);
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// The radius of a particle in the PM2.5 channel is .44 µm
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double r25 = 0.44 * pow (10, -6);
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double vol25 = (4/3) * pi * pow (r25, 3);
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double mass25 = density * vol25; // ug
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double K = 3531.5; // per m^3
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return concentration_pcs * K * mass25;
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}
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@ -1,5 +1,7 @@
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/*
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* Author: Jon Trulson <jtrulson@ics.com>
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* Contributions: Rex Tsai <rex.cc.tsai@gmail.com>
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* Abhishek Malik <abhishek.malik@intel.com>
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* Copyright (c) 2016 Intel Corporation.
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*
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* Based on original C++ driver written by:
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@ -37,6 +39,8 @@ extern "C" {
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unsigned int lowPulseOccupancy;
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double ratio;
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double concentration;
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double ugm3;
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int aqi;
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} ppd42ns_dust_data;
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#ifdef __cplusplus
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@ -1,7 +1,9 @@
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/*
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* Authors:
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* Jon Trulson <jtrulson@ics.com>
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* Copyright (c) 2016 Intel Corporation.
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* Contributions: Rex Tsai <rex.cc.tsai@gmail.com>
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* Abhishek Malik <abhishek.malik@intel.com>
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* Copyright (c) 2017 Intel Corporation.
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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@ -32,6 +34,22 @@
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#include <upm_platform.h>
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#include <upm_utilities.h>
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// https://airnow.gov/index.cfm?action=aqibasics.aqi
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static struct aqi {
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float clow;
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float chigh;
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int llow;
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int lhigh;
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} aqi[] = {
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{0.0, 12.4, 0, 50},
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{12.1, 35.4, 51, 100},
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{35.5, 55.4, 101, 150},
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{55.5, 150.4, 151, 200},
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{150.5, 250.4, 201, 300},
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{250.5, 350.4, 301, 350},
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{350.5, 500.4, 401, 500},
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};
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void upm_delay(unsigned int time)
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{
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if (time <= 0)
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@ -246,3 +264,19 @@ uint32_t upm_elapsed_us(upm_clock_t *clock)
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return elapsed;
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#endif
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}
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int upm_ugm3_to_aqi (double ugm3)
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{
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int i;
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for (i = 0; i < 7; i++) {
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if (ugm3 >= aqi[i].clow &&
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ugm3 <= aqi[i].chigh) {
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// Ip = [(Ihi-Ilow)/(BPhi-BPlow)] (Cp-BPlow)+Ilow,
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return ((aqi[i].lhigh - aqi[i].llow) / (aqi[i].chigh - aqi[i].clow)) *
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(ugm3 - aqi[i].clow) + aqi[i].llow;
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}
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}
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return 0;
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}
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@ -1,7 +1,9 @@
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/*
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* Authors:
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* Jon Trulson <jtrulson@ics.com>
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* Copyright (c) 2016 Intel Corporation.
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* Contributions: Rex Tsai <rex.cc.tsai@gmail.com>
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* Abhishek Malik <abhishek.malik@intel.com>
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* Copyright (c) 2017 Intel Corporation.
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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@ -113,6 +115,15 @@ uint32_t upm_elapsed_ms(upm_clock_t *clock);
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*/
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uint32_t upm_elapsed_us(upm_clock_t *clock);
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/**
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* Return the AQI (based on EPA standards) using the ugm3 value
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* calculated by the sensor module.
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*
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* @param ugm3 micrograms per cubic meter
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* @return calculated AQI
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*/
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int upm_ugm3_to_aqi (double ugm3);
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#ifdef __cplusplus
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}
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#endif
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