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Concentration to AQI calculation for US and China. #12

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Dec 23, 2024
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Concentration to AQI calculation for US and China. #12

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Concentration to AQI calculation for US and China. Add fail reason an…
jiangyi1985 Jul 23, 2022
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better data printing
jiangyi1985 Jul 23, 2022
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format code
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use clang format
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clang format head file
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add doxygen documentation
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comment clang format
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updates for PR change request
jiangyi1985 Dec 18, 2024
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something missed from last change request fix
jiangyi1985 Dec 19, 2024
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Merge branch 'master' into master
jiangyi1985 Dec 19, 2024
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172 changes: 170 additions & 2 deletions Adafruit_PM25AQI.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@
*/

#include "Adafruit_PM25AQI.h"
#include <math.h>

/*!
* @brief Instantiates a new PM25AQI class
Expand Down Expand Up @@ -104,17 +105,23 @@ bool Adafruit_PM25AQI::read(PM25_AQI_Data *data) {
return false;
}

memcpy((void *)data->raw, (void *)buffer, 32);

// Check that start byte is correct!
if (buffer[0] != 0x42) {
if (buffer[0] != 0x42 || buffer[1] != 0x4d) {
data->startbyte_fail = 1;
return false;
} else {
data->startbyte_fail = 0;
}

// get checksum ready
for (uint8_t i = 0; i < 30; i++) {
sum += buffer[i];
}

// The data comes in endian'd, this solves it so it works on all platforms
// The data comes in big endian (MSB first), this solves it so it works on all
// platforms
uint16_t buffer_u16[15];
for (uint8_t i = 0; i < 15; i++) {
buffer_u16[i] = buffer[2 + i * 2 + 1];
Expand All @@ -124,10 +131,171 @@ bool Adafruit_PM25AQI::read(PM25_AQI_Data *data) {
// put it into a nice struct :)
memcpy((void *)data, (void *)buffer_u16, 30);

data->datasum = sum;
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if (sum != data->checksum) {
data->checksum_fail = 1;
return false;
} else {
data->checksum_fail = 0;
}

data->version = buffer[28];
data->error_code = buffer[29];

// convert concentration to AQI
data->aqi_pm25_us = pm25_aqi_us(data->pm25_env);
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data->aqi_pm25_china = pm25_aqi_china(data->pm25_env);
data->aqi_pm100_us = pm100_aqi_us(data->pm100_env);
data->aqi_pm100_china = pm100_aqi_china(data->pm100_env);

// success!
return true;
}

/*!
* @brief Get AQI of PM2.5 in US standard
* @param concentration
* the environmental concentration of pm2.5 in ug/m3
* @return AQI number. 0 to 500 for valid calculation. 99999 for out of range.
*/
uint16_t Adafruit_PM25AQI::pm25_aqi_us(float concentration) {
float c;
float AQI;
c = (floor(10 * concentration)) / 10;
if (c < 0)
AQI = 0;
else if (c >= 0 && c < 12.1f) {
AQI = linear(50, 0, 12, 0, c);
} else if (c >= 12.1f && c < 35.5f) {
AQI = linear(100, 51, 35.4f, 12.1f, c);
} else if (c >= 35.5f && c < 55.5f) {
AQI = linear(150, 101, 55.4f, 35.5f, c);
} else if (c >= 55.5f && c < 150.5f) {
AQI = linear(200, 151, 150.4f, 55.5f, c);
} else if (c >= 150.5f && c < 250.5f) {
AQI = linear(300, 201, 250.4f, 150.5f, c);
} else if (c >= 250.5f && c < 350.5f) {
AQI = linear(400, 301, 350.4f, 250.5f, c);
} else if (c >= 350.5f && c < 500.5f) {
AQI = linear(500, 401, 500.4f, 350.5f, c);
} else {
AQI = 99999; //
}
return round(AQI);
}

/*!
* @brief Get AQI of PM10 in US standard
* @param concentration
* the environmental concentration of pm10 in ug/m3
* @return AQI number. 0 to 500 for valid calculation. 99999 for out of range.
*/
uint16_t Adafruit_PM25AQI::pm100_aqi_us(float concentration) {
float c;
float AQI;
c = concentration;
if (c < 0)
AQI = 0;
else if (c < 55) {
AQI = linear(50, 0, 55, 0, c);
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} else if (c < 155) {
AQI = linear(100, 51, 155, 55, c);
} else if (c < 255) {
AQI = linear(150, 101, 255, 155, c);
} else if (c < 355) {
AQI = linear(200, 151, 355, 255, c);
} else if (c < 425) {
AQI = linear(300, 201, 425, 355, c);
} else if (c < 505) {
AQI = linear(400, 301, 505, 425, c);
} else if (c < 605) {
AQI = linear(500, 401, 605, 505, c);
} else {
AQI = 99999; //
}
return round(AQI);
}

/*!
* @brief Get AQI of PM2.5 in China standard
* @param concentration
* the environmental concentration of pm2.5 in ug/m3
* @return AQI number. 0 to 500 for valid calculation. 99999 for out of range.
*/
uint16_t Adafruit_PM25AQI::pm25_aqi_china(float concentration) {
float c;
float AQI;
c = concentration;
if (c < 0)
AQI = 0;
else if (c <= 35) {
AQI = linear(50, 0, 35, 0, c);
} else if (c <= 75) {
AQI = linear(100, 51, 75, 35, c);
} else if (c <= 115) {
AQI = linear(150, 101, 115, 75, c);
} else if (c <= 150) {
AQI = linear(200, 151, 150, 115, c);
} else if (c <= 250) {
AQI = linear(300, 201, 250, 150, c);
} else if (c <= 350) {
AQI = linear(400, 301, 350, 250, c);
} else if (c <= 500) {
AQI = linear(500, 401, 500, 350, c);
} else {
AQI = 99999; //
}
return round(AQI);
}

/*!
* @brief Get AQI of PM10 in China standard
* @param concentration
* the environmental concentration of pm10 in ug/m3
* @return AQI number. 0 to 500 for valid calculation. 99999 for out of range.
*/
uint16_t Adafruit_PM25AQI::pm100_aqi_china(float concentration) {
float c;
float AQI;
c = concentration;
if (c < 0)
AQI = 0;
else if (c <= 50) {
AQI = linear(50, 0, 50, 0, c);
} else if (c <= 150) {
AQI = linear(100, 51, 150, 50, c);
} else if (c <= 250) {
AQI = linear(150, 101, 250, 150, c);
} else if (c <= 350) {
AQI = linear(200, 151, 350, 250, c);
} else if (c <= 420) {
AQI = linear(300, 201, 420, 350, c);
} else if (c <= 500) {
AQI = linear(400, 301, 500, 420, c);
} else if (c <= 600) {
AQI = linear(500, 401, 600, 500, c);
} else {
AQI = 99999; //
}
return round(AQI);
}

/*!
* @brief Linearly map a concentration value to its AQI level
* @param aqi_high max aqi of the calculating range
* @param aqi_low min aqi of the calculating range
* @param conc_high max concentration value (ug/m3) of the calculating range
* @param conc_low min concentration value (ug/m3) of the calculating range
* @param concentration
* the concentration value to be calculated
* @return Calculated AQI value
*/
float Adafruit_PM25AQI::linear(uint16_t aqi_high, uint16_t aqi_low,
float conc_high, float conc_low,
float concentration) {
float f;
f = ((concentration - conc_low) / (conc_high - conc_low)) *
(aqi_high - aqi_low) +
aqi_low;
return f;
}
34 changes: 32 additions & 2 deletions Adafruit_PM25AQI.h
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Original file line number Diff line number Diff line change
Expand Up @@ -41,8 +41,31 @@ typedef struct PMSAQIdata {
particles_25um, ///< 2.5um Particle Count
particles_50um, ///< 5.0um Particle Count
particles_100um; ///< 10.0um Particle Count
uint16_t unused; ///< Unused
uint16_t checksum; ///< Packet checksum
uint16_t unused; ///< Unused (version + error code)

// when copy data from int8 array to this struct with memcpy, error_code need
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// to be defined before version otherwise they are swapped. reason is that
// arduino is little endian and memcpy swap the bytes when copy int16 into the
// 2 int8s? will manually copy them instead
// uint8_t error_code; ///<
// uint8_t version; ///<

uint16_t checksum; ///< Packet checksum

// verbose infos:
uint16_t datasum; ///< the calculated sum of the data in the current packet
uint8_t startbyte_fail; ///< startbyte check fail?: 1 - fail, 0 - success
uint8_t checksum_fail; ///< checksum check fail?: 1 - fail, 0 - success
uint8_t version; ///< version number
uint8_t error_code; ///< error code
uint8_t raw[32]; ///< raw packet data

// AQI conversion results:
uint8_t aqi_pm25_us; ///< pm2.5 AQI of United States
uint8_t aqi_pm100_us; ///< pm10 AQI of United States
uint8_t aqi_pm25_china; ///< pm2.5 AQI of China
uint8_t aqi_pm100_china; ///< pm10 AQI of China

} PM25_AQI_Data;

/*!
Expand All @@ -56,6 +79,13 @@ class Adafruit_PM25AQI {
bool begin_UART(Stream *theStream);
bool read(PM25_AQI_Data *data);

uint16_t pm25_aqi_us(float concentration);
uint16_t pm25_aqi_china(float concentration);
uint16_t pm100_aqi_us(float concentration);
uint16_t pm100_aqi_china(float concentration);
float linear(uint16_t aqi_high, uint16_t aqi_low, float conc_high,
float conc_low, float concentration);

private:
Adafruit_I2CDevice *i2c_dev = NULL;
Stream *serial_dev = NULL;
Expand Down
37 changes: 33 additions & 4 deletions examples/PM25_test/PM25_test.ino
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Original file line number Diff line number Diff line change
Expand Up @@ -42,20 +42,24 @@ void loop() {

if (! aqi.read(&data)) {
Serial.println("Could not read from AQI");

//print verbose info
// Serial.println("FAIL reading. Error info:");
// printInfo(data);
// Serial.println();

delay(500); // try again in a bit!
return;
}
Serial.println("AQI reading success");

Serial.println();
Serial.println(F("---------------------------------------"));
Serial.println(F("Concentration Units (standard)"));
Serial.println(F("---------------------------------------"));
Serial.print(F("PM 1.0: ")); Serial.print(data.pm10_standard);
Serial.print(F("\t\tPM 2.5: ")); Serial.print(data.pm25_standard);
Serial.print(F("\t\tPM 10: ")); Serial.println(data.pm100_standard);
Serial.println(F("Concentration Units (environmental)"));
Serial.println(F("---------------------------------------"));
Serial.println(F("Concentration Units (environmental)"));
Serial.print(F("PM 1.0: ")); Serial.print(data.pm10_env);
Serial.print(F("\t\tPM 2.5: ")); Serial.print(data.pm25_env);
Serial.print(F("\t\tPM 10: ")); Serial.println(data.pm100_env);
Expand All @@ -67,7 +71,32 @@ void loop() {
Serial.print(F("Particles > 5.0um / 0.1L air:")); Serial.println(data.particles_50um);
Serial.print(F("Particles > 10 um / 0.1L air:")); Serial.println(data.particles_100um);
Serial.println(F("---------------------------------------"));

Serial.println(F("AQI"));
Serial.print(F("PM2.5 AQI US: ")); Serial.print(data.aqi_pm25_us);
Serial.print(F("\tPM10 AQI US: ")); Serial.println(data.aqi_pm100_us);
// Serial.print(F("PM2.5 AQI China: ")); Serial.print(data.aqi_pm25_china);
// Serial.print(F("\tPM10 AQI China: ")); Serial.println(data.aqi_pm100_china);
Serial.println(F("---------------------------------------"));
Serial.println();

delay(1000);
}

void printInfo(PM25_AQI_Data data)
{
Serial.print(F("startbyte_fail: ")); Serial.println(data.startbyte_fail);
Serial.print(F("checksum_fail: ")); Serial.println(data.checksum_fail);
Serial.print(F("framelen: ")); Serial.println(data.framelen);
Serial.print(F("version: ")); Serial.println(data.version);
Serial.print(F("error_code: ")); Serial.println(data.error_code);
Serial.print(F("checksum: ")); Serial.println(data.checksum);
Serial.print(F("datasum: ")); Serial.println(data.datasum);
Serial.println(F("raw data: "));
for(int i = 0; i < sizeof(data.raw); i++)
{
Serial.print(data.raw[i]);
Serial.print("\t");
if((i+1)%2==0)
Serial.println();
}
}