Air Quality Monitoring Station (AQMS)

After a long time I decided to share my Personal Weather Station.
It is based on my PMS library (https://github.com/fu-hsi/PMS).

Installation

Configuration

Before uploading code, change configuration:

// Don't touch this ;-)
// #define FU_PROFILE

#ifdef FU_PROFILE
#include "Settings.h"
#else
// Debug (D4)
#define DBG Serial1

// Webservice
static const char* WS_UA = "AQMS/2.0";
static const char* WS_TOKEN = "YOUR TOKEN";
static const char* WS_URL = "YOUR SERVER SCRIPT";

// Wireless credentials
static const char* WL_SSID = "YOUR SSID";
static const char* WL_PASS = "YOUR PASSWORD";
static const uint8_t WL_CHANNEL = 0;

// OTA credentials
static const char* BE_USERNAME = "admin";
static const char* BE_PASSWORD = "admin";

// PMS configuration (INTERVAL & DELAY can't be equal!!!)
static const uint32_t PMS_READ_INTERVAL = 150000;
static const uint32_t PMS_READ_DELAY = 30000;

// Takes N samples and counts the average
static const uint8_t PMS_READ_SAMPLES = 2;
#endif // FU_PROFILE

Board settings

Board identification

If you have any problems, use flashInfo() function to identify board or CheckFlashConfig.ino (it's the same). This is very imporant for OTA update.

Circuit

I don't have necessary components for Fritzing, sorry...

Component	WeMos	Note
Debug output	D4
Battery monitor	A1	100k resistor in series (max. 4.2V).
PMS7003	TX => RX RX => TX VCC => 5V GND => GND	Disconnect before programming via a usb port!
SHT31-D	SDA => D1 SCL => D2 VCC => 3.3V GND => GND	For temperature and humidity (built-in heater).
BME280	SDA => D1 SCL => D2 VCC => 3.3V GND => GND	For pressure and temperature (temperature and humidity as backup).

Alternative sensors

I testet many sensors... The following list shows my ranking.

Rank	Sensor	Note
1	SHT31-D	Temperature, Humidity (built-in heater, Filter Caps are also available).
2	BMP280	Temperature, Pressure.
3	BMP180	Temperature, Pressure.
4	BME280	Temperature, Humidity, Pressure.
5	DHT22 (AM2302)	Temperature, Humidity.

Don't use BME280 for measuring temperature... I get readings overstated more than 2°C.
DHT22 is also a bad choice for measuring humidity.
Best combo for me is SHT31-D with BMP280, but BMP280 stopped working properly before publishing this project and I use BME280 now.

Dashboard

Components

• Radiation shield TFA 98.1114.02
• Wemos D1 ESP-WROOM-02
• Plantower PMS7003
• SHT31-D
• BME280

Measured values

• Pollution
• Temperature and humidity
• Pressure
• Battery voltage

Additional features

• OTA update over Wi-Fi
• Sending data to the server
• Mobility (Lithium-ion battery)
• Battery monitor
• File logging

Working time

Up to 8 hours with listed conditions:

• Default configuration
• Li-Ion ~1500mAh
• Temperature ~3°C

Photos

Rev. 1

In surface mounted S-BOX 116B IP65 (old hardware).

Rev. 2

Merged with my previous meteorological station in the radiation shield.

Mounted on the balcony and powered through a thin cable connected to a PC USB.
USB socket in WeMos was removed (accidentally ;-).

Couple pictures from inside.

Database

Table structure

CREATE TABLE `weather_pms` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `dt` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `pm1` smallint(6) DEFAULT NULL,
  `pm25` smallint(6) DEFAULT NULL,
  `pm10` smallint(6) DEFAULT NULL,
  `rv` smallint(6) DEFAULT NULL,
  `v` float(4,2) DEFAULT NULL,
  `temperature` float(4,2) DEFAULT NULL,
  `humidity` float(4,2) DEFAULT NULL,
  `pressure` float(6,2) DEFAULT NULL,
  `bm280_temp` float(4,2) DEFAULT NULL,
  `bm280_hum` float(4,2) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=146810 DEFAULT CHARSET=utf8;

Sample data

    id                   dt     pm1    pm25    pm10      rv       v  temperature  humidity  pressure  bm280_temp  bm280_hum  
------  -------------------  ------  ------  ------  ------  ------  -----------  --------  --------  ----------  -----------
146810  2018-12-17 22:00:57      22      40      52    1024    4.20        -0.79     95.15   1008.28       -0.26        81.28
146809  2018-12-17 21:57:57      26      44      66    1024    4.20        -0.72     94.94   1008.31       -0.17        80.95
146808  2018-12-17 21:54:57      22      36      40    1024    4.20        -0.76     94.93   1008.31       -0.28        81.25
146807  2018-12-17 21:51:57      18      34      43    1024    4.20        -0.79     95.20   1008.26       -0.17        81.19
146806  2018-12-17 21:48:57      16      34      50    1024    4.20        -0.92     95.49   1008.25       -0.35        81.66
146805  2018-12-17 21:45:57      22      40      52    1024    4.20        -0.93     95.45   1008.27       -0.41        81.77

Server

I have PHP script on my VPS server where I receive POST data. These data are then sent (after some calculations) to:

• SQL Database
• https://thingspeak.com/
• https://www.wunderground.com/

What calculations do I mean? For example:

• Reduced pressure
• Heat Index
• Dev Point

I also reject the results below a certain voltage.

For simplicity, I share only a basic ws.php script. Rest is in your gesture.

<?php
error_reporting(0);
ini_set('display_errors', 0);
date_default_timezone_set('Europe/Warsaw');

// define('FU_PROFILE', true);

if (defined('FU_PROFILE')) {
    require_once 'config.php';
} else {
    define('WS_TOKEN', 'YOUR TOKEN');

    define('DB_HOST', 'YOUR DB HOST');
    define('DB_USER', 'YOUR DB USER');
    define('DB_PASS', 'YOUR DB PASS');
    define('DB_NAME', 'YOUR DB NAME');
}

class DB
{
    private static $db = null;
    private function __construct()
    {}
    public static function getConnection()
    {
        if (self::$db == null) {
            $dsn = sprintf('mysql:dbname=%s;host=%s', DB_NAME, DB_HOST);
            $options = array(
                PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8",
                PDO::ATTR_ERRMODE => PDO::ERRMODE_SILENT,
                PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
            );
            self::$db = new PDO($dsn, DB_USER, DB_PASS, $options);
        }
        return self::$db;
    }
}

if (!empty($_SERVER['HTTP_X_TOKEN']) && $_SERVER['HTTP_X_TOKEN'] == WS_TOKEN) {
 
  // Allowed fields
  $whiteList = [
    'pm1', 'pm25', 'pm10',
    'rv', 'v',
    'temperature', 'humidity', 'pressure', 'bm280_temp', 'bm280_hum'
  ];  

  // Clear array
  $whiteList = array_fill_keys($whiteList, NULL);

  // Prepare array
  $storeData = [];
  $storeData = array_merge($storeData, $whiteList, array_intersect_key($_POST, $whiteList));

  try {   
    $db = DB::getConnection();
    $stm = $db->prepare('INSERT INTO weather_pms SET dt = NOW(), ' . implode(',', array_map(function ($key) {
      return $key . ' = :' . $key;
    }, array_keys($storeData))));
    $stm->execute($storeData);   
  } catch(PDOException $e) {
    exit('DB error');
  }

}
?>

Typical flow

Todo

• Add a GPS module for use in the field (https://github.com/fu-hsi/FuGPS).
  UTC time from GPS is an extra bonus for work in offline mode.