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AQI: Adding ugm3 calculation to ppd42ns and aqi calculation to upm_utilities

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Contributions by: Rex Tsai <rex.cc.tsai@gmail.com>

Signed-off-by: Abhishek Malik <abhishek.malik@intel.com>
This commit is contained in:
Abhishek Malik
2017-02-10 11:49:11 -08:00
parent b9988469ba
commit 7a60cd5abe
4 changed files with 79 additions and 2 deletions
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28
src/ppd42ns/ppd42ns.c
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@ -1,5 +1,7 @@
/*
* Author: Jon Trulson <jtrulson@ics.com>
* Contributions: Rex Tsai <rex.cc.tsai@gmail.com>
* Abhishek Malik <abhishek.malik@intel.com>
* Copyright (c) 2016 Intel Corporation.
*
* Rewritten Based on original C++ driver written by:
@ -39,6 +41,7 @@
// from LOW to HIGH
static uint32_t ppd42ns_pulse_in(const ppd42ns_context dev,
bool high_low_value);
double pcs2ugm3 (double concentration_pcs);
ppd42ns_context ppd42ns_init(int pin)
{
@ -112,6 +115,8 @@ ppd42ns_dust_data ppd42ns_get_data(const ppd42ns_context dev)
data.lowPulseOccupancy = low_pulse_occupancy;
data.ratio = ratio;
data.concentration = concentration;
data.ugm3 = pcs2ugm3(data.concentration);
data.aqi = upm_ugm3_to_aqi(data.ugm3);
return data;
}
@ -165,3 +170,26 @@ static uint32_t ppd42ns_pulse_in(const ppd42ns_context dev,
return total_pulse_time;
}
// Assumes density, shape, and size of dust to estimate mass concentration from particle count.
//
// This method was described in a 2009 paper
// Preliminary Screening System for Ambient Air Quality in Southeast Philadelphia by Uva, M., Falcone, R., McClellan, A., and Ostapowicz, E.
// https://www.yumpu.com/en/document/view/31692906/preliminary-screening-system-for-ambient-air-quality-in-southeast-
//
// This method does not use the correction factors, based on the presence of humidity and rain in the paper.
//
// convert from particles/0.01 ft3 to <20>g/m3
double pcs2ugm3 (double concentration_pcs)
{
double pi = 3.14159;
// All particles are spherical, with a density of 1.65E12 <20>g/m3
double density = 1.65 * pow (10, 12);
// The radius of a particle in the PM2.5 channel is .44 <20>m
double r25 = 0.44 * pow (10, -6);
double vol25 = (4/3) * pi * pow (r25, 3);
double mass25 = density * vol25; // ug
double K = 3531.5; // per m^3
return concentration_pcs * K * mass25;
}

4
src/ppd42ns/ppd42ns_data.h
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@ -1,5 +1,7 @@
/*
* Author: Jon Trulson <jtrulson@ics.com>
* Contributions: Rex Tsai <rex.cc.tsai@gmail.com>
* Abhishek Malik <abhishek.malik@intel.com>
* Copyright (c) 2016 Intel Corporation.
*
* Based on original C++ driver written by:
@ -37,6 +39,8 @@ extern "C" {
unsigned int lowPulseOccupancy;
double ratio;
double concentration;
double ugm3;
int aqi;
} ppd42ns_dust_data;
#ifdef __cplusplus