Set up a Wio Terminal as a Remote Outdoor Air Quality Monitor Display using Machinechat and MQTT

ScottRaeker · March 30, 2022, 8:34pm

Description

This project sets up a Seeed Wio Terminal as a remote outdoor air quality display that shows ozone (O₃) and Particulate Matter (PM2.5 and PM10) data. The Wio Terminal receives AQI data over WiFi by subscribing to live sensor data using MQTT with Machinechat’s JEDI One IoT data platform. Arduino is used to implement the Wio Terminal application and JEDI One is installed and running on a Raspberry Pi 4.

Hardware

RASPBERRY PI 4B/4GB
Raspberry PI 4 Model B with 4GB SDRAM
Seeed Wio Terminal
Wio Terminal is a standalone Arduino/MicroPython compatible SAMD51-based microcontroller evaluation platform with WiFi/Bluetooth powered by a Realtek RTL8720DN. It is equipped with a 2.4” LCD Screen, onboard IMU(LIS3DHTR), Microphone, Buzzer, microSD card slot, Light sensor, and Infrared Emitter(IR 940nm).

Software

JEDI One
JEDI One is a ready-to-use IoT data management software solution. Capabilities include: collect data from sensors, devices and machines; build intuitive real-time and historical data and system view dashboards; create rules to monitor and respond to data conditions automatically; receive alert notifications by email and SMS.
Arduino
Arduino is an open-source electronics platform based on easy-to-use hardware and software.

Background

The primary air pollutants monitored by the US Environmental Protection Agency(EPA) monitors are ozone and Particulate Matter. Below map from https://www.airnow.gov/ is an interactive GUI that provides information on air quality throughout the US.

Ground-level ozone can trigger a variety of health problems, particularly for children, the elderly, and people of all ages who have lung diseases such as asthma. Particulate matter (PM2.5 and PM10) contains microscopic solids or liquid droplets that can be inhaled and cause serious health problems.

Implementation

The project uses a Wio Terminal to implement a remote outdoor air quality display and Arduino is used to implement the code. The Wio Terminal is set up to connect over WiFi to the MQTT broker running on the JEDI One. Once connected, it subscribes to ozone and PM air quality sensor data being collected by the JEDI One. The LCD display is used to provide air quality information as shown below.

The display shows AQI values, color coded AQI level, color coded timestamp of the most recent data received and a rolling two value chart showing the last 50 sensor readings. The JEDI One is also configured to display the sensor data in widgets on the Sensor Dashboard.

Note: This project builds on two other Machinechat sensor projects that provide ozone and PM data to Machinechat’s JEDI One IoT Data Platform. First project is Machinechat with Renesas ZMOD4510 Outdoor Air Quality Sensor. Second project is Machinechat with Panasonic SN-GCJA5 Air Quality (PM) Sensor.

Set up the Wio Terminal platform for the Arduino application

1 - Set up Arduino on the Wio Terminal. See link Getting started with Wio Terminal
note: make sure Realtek RTL8720DN firmware is updated per Update the Wireless Core Firmware

2 - Install libraries needed for application. Add these libraries thru Arduino’s Library Manager:

note: add “Free_Fonts.h” and “arduino_secrets.h” files to project directory (Free_Fonts.h is located in ~/Arduino/libraries/Seeed_LCD_master/examples/320 x 240/All_Free_Fonts_Demo)

3 - Code walkthrough (filename: WioTerminalMQTTDisplay2topicOAQrev2.ino)

Setup LCD display, connect to WiFi network, connect to MQTT broker and parse JSON MQTT messages

/*
 Wio Terminal MQTT data display example 
 filename: WioTerminalMQTTDisplay2topicOAQ.ino
 project based on WioTerminalMQTTDisplay.ino which is a sketch that demonstrates using the Wio Terminal to mqtt subscribe to air quality sensor data on the 
 machinechat JEDI One IoT data platform. It uses WiFi to connect to the JEDI One MQTT broker.
 Ozone air quality sensor data - Renesas
 Particle air quality sensor date - Panasonic
 11/10/2021 - this project takes sketch WioTerminalMQTTDisplay.ino and modifies to subscribe to 2 topics and changes topics to outdoor air quality sensors for 
 ozone and particulate matter to display AQI
 11/16/2021 - clean up code and change to version to "_rev1", also add 3rd subtopic for testing
 3/30/2022 - rev2 change back to subscribe to just two topics (comment out subtopic1
*/

#include <rpcWiFi.h>
#include <PubSubClient.h>
#include <TFT_eSPI.h>
#include "Free_Fonts.h"
#include"seeed_line_chart.h" //include the library

TFT_eSPI tft;

// for LCD line chart
#define max_size 50 //maximum size of data
doubles data[2]; //Initilising a doubles type to store data
TFT_eSprite spr = TFT_eSprite(&tft);  // Sprite 


char value[7] = "      "; //initial values
char value2[7] = "      ";
char stamp[40] = "2021-09-01T13:04:34"; 

//#include <ESP8266WiFi.h>
//#include <PubSubClient.h>
#include <ArduinoJson.h>
#include "arduino_secrets.h" 

// Update these with values suitable for your network.
char ssid[] = SECRET_SSID;     // your network SSID (name)
char pass[] = SECRET_PASS;    // your network password (use for WPA, or use as key for WEP)

// MQTT server info for JEDI One
const char* mqttServer = "192.168.1.7";
const int mqttPort = 1883;

StaticJsonDocument<256> doc;

int data1 = 0;  //data1 of MQTT json message
int data2 = 0;  //data2 of MQTT json message
int data3 = 0;  //data3 of MQTT json message
int data4 = 0;  //data3 of MQTT json message
int msg = 0;
const char* timestamp = "dummy data";  //the is the MQTT message timestamp (this works)
String recv_payload;
const char* subtopic1 = "datacache/T960981B2D";                //pump house humidity, temp sensor
const char* subtopic2 = "datacache/MKR1010_Z4510oaq2S31PMOD";  //ZMOD4510 air quality/ozone sensor
const char* subtopic3 = "datacache/MKR1010WiFiSensor_SNGCJA5"; //SNGCJA5x air quality particl sensor

// wio terminal wifi 
WiFiClient wclient;
PubSubClient client(wclient); // Setup MQTT client

void setup_wifi() {

  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, pass);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  randomSeed(micros());
  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

// mqtt message callback
void callback(char* topic, byte* payload, unsigned int length) {

  //print out message topic and payload  
  Serial.print("New message from Subscribe topic: ");
  Serial.println(topic);
  Serial.print("Subscribe JSON payload: ");
  for (int i = 0; i < length; i++) {
    Serial.print((char)payload[i]);     // print mqtt payload
  }
  Serial.println();

  msg = 1;  //set message flag = 1 when new subscribe message received

  
  //check subscribe topic for message received and decode    
  
  //********************************//
  //if message from topic subtopic1
  //********************************//
  if (strcmp(topic, subtopic1)== 0) {  
    // "clear" old data by rewriting old info in white
    tft.setTextColor(TFT_WHITE);   //"clear" old data by rewriting old info in white
    tft.setFreeFont(FF19);
    tft.drawString(value,200,78); 
    //tft.drawString(value2,60,78);  //value2 is same as data2
    tft.setFreeFont(FF18);
    tft.drawString(stamp,60,110);             

    Serial.print("decode payload from topic ");
    Serial.println(topic);
    deserializeJson(doc, (const byte*)payload, length);   //parse MQTT message
    data1 = doc["data1"];    // data1 is humidity
    //data2 = data4;           // data4 is O3 FastAQI
    //data2 = doc["data2"];    // data2 is temp
    //data3 = doc["data3"];    // data3 is empty
    timestamp = doc["timestamp"];    //mqtt message timestamp
    //  stamp = timestamp;
    strcpy (stamp,timestamp);
    stamp[19] = 0;   // terminate string after seconds
    Serial.println(stamp);     //debug print

    tft.setTextColor(TFT_MAGENTA);
    tft.setFreeFont(FF19);     
    itoa(data1,value,10);  //convert data integer value to character
    tft.drawString(value,200,78);//prints data at (x,y)
    //itoa(data2,value2,10);  
    //tft.setTextColor(TFT_BLUE);
    //tft.drawString(value2,60,78);  
    tft.setTextColor(TFT_BLACK);
    tft.setFreeFont(FF18);
    tft.drawString(stamp,60,110); //print timestamp
  }
  //********************************//
  //if message from topic subtopic2
  //********************************//
  if (strcmp(topic, subtopic2)== 0) {   
    // "clear" old data by rewriting old info in white
    tft.setTextColor(TFT_WHITE);   //"clear" old data by rewriting old info in white
    tft.setFreeFont(FF19);
    tft.drawString(value2,50,78);  //"clear" old value2 (is same as data2)  
    tft.setFreeFont(FF18);
    tft.drawString(stamp,60,110);   //"clear" old timestamp      
    
    Serial.print("decode payload from topic ");
    Serial.println(topic);
    deserializeJson(doc, (const byte*)payload, length);   //parse MQTT message
//    data1 = doc["data1"];    
    data2 = doc["FastAQI"];    // 
    itoa(data2,value2,10); 
    tft.setFreeFont(FF19); 
    tft.setTextColor(TFT_BLUE);
    tft.drawString(value2,50,78);  //print new value2 on LCD
    Serial.print("data2 is O3 FastAQI = ");
    Serial.println(data2);
    
    timestamp = doc["timestamp"];    //mqtt message timestamp
    //  stamp = timestamp;
    strcpy (stamp,timestamp);
    stamp[19] = 0;   // terminate string after seconds     
    tft.setTextColor(TFT_BLUE);
    tft.setFreeFont(FF18);
    tft.drawString(stamp,60,110); //print new timestamp on LCD   
    
    //print out color of "AQI" font based on value of AQI
    // <50=green,51to100=yellow,101to150=orange,>150=red
    if (data2 < 51) {
      tft.setTextColor(TFT_GREEN);
    }
    else if (data2 < 101){
      tft.setTextColor(TFT_YELLOW);
    }
    else if (data2 < 151){
      tft.setTextColor(TFT_ORANGE);
    }
    else {
      tft.setTextColor(TFT_RED);  
    }
    tft.setFreeFont(FF18);
    tft.drawString("AQI",100,78);
     
  }
    
  //********************************//
  //if message from topic subtopic3
  //********************************//
  if (strcmp(topic, subtopic3)== 0) {   
    // "clear" old data by rewriting old info in white
    tft.setTextColor(TFT_WHITE);   //"clear" old data by rewriting old info in white
    tft.setFreeFont(FF19);
    tft.drawString(value,200,78);  //"clear" old value   
    tft.setFreeFont(FF18);
    tft.drawString(stamp,60,110);   //"clear" old timestamp   

    Serial.print("decode payload from topic ");
    Serial.println(topic);
    deserializeJson(doc, (const byte*)payload, length);   //parse MQTT message
    data3 = doc["aqiPM2_5"];
    data4 = doc["aqiPM10"];
    Serial.print("data3 = aqiPM2_5 = ");
    Serial.println(data3);
    Serial.print("data4 = aqiPM10 = ");
    Serial.println(data4);
    // determine which PM2.5 or PM10 is larger to use when displaying PM AQI
    if (data3 >= data4) {
      data1 = data3;
    }
    else {
      data1 = data4;
    }
    Serial.print("Particle AQI = ");
    Serial.println(data1);
    tft.setTextColor(TFT_MAGENTA);
    tft.setFreeFont(FF19);     
    itoa(data1,value,10);  //convert data integer to character "value"
    tft.drawString(value,200,78);//prints "value" at (x,y)

    timestamp = doc["timestamp"];    //mqtt message timestamp
    strcpy (stamp,timestamp);
    stamp[19] = 0;   // terminate string after seconds     
    tft.setTextColor(TFT_MAGENTA);
    tft.setFreeFont(FF18);
    tft.drawString(stamp,60,110); //print new timestamp on LCD 

    //print out color of "AQI" font based on value of AQI
    // <50=green,51to100=yellow,101to150=orange,>150=red
    if (data1 < 51) {
      tft.setTextColor(TFT_GREEN);
    }
    else if (data1 < 101){
      tft.setTextColor(TFT_YELLOW);
    }
    else if (data1 < 151){
      tft.setTextColor(TFT_ORANGE);
    }
    else {
      tft.setTextColor(TFT_RED);  
    }
    tft.setFreeFont(FF18);
    tft.drawString("AQI",250,78);
  }
}

//connect to mqtt broker on JEDI One and subscribe to topics
void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Create a unique client ID using the Wio Terminal MAC address
    String MACadd = WiFi.macAddress();
    MACadd = "WioTerminal" + MACadd;  
    String clientID = MACadd;

    // Attempt to connect
    if (client.connect(clientID.c_str())) {
      Serial.println("connected");
      // set up MQTT topic subscription     note: topic needs to be "datacache/" + Device on JEDI One 
      Serial.println("subscribing to topics:");
      //Serial.println(subtopic1);        //comment out subtopic1 for this revision of code
      //client.subscribe(subtopic1);        
      Serial.println(subtopic2);
      client.subscribe(subtopic2); 
      Serial.println(subtopic3);
      client.subscribe(subtopic3); 
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void setup() {
  // setup lcd display
  tft.begin();
  tft.setRotation(3);
  tft.fillScreen(TFT_WHITE); //Black background
  spr.createSprite(320,110); //try 320x110
  tft.setFreeFont(FF19); //select font
  tft.setTextColor(TFT_BLACK  );
  tft.drawString("Outdoor Air ",5,5);
  tft.drawString("Quality",195,5);
  tft.setTextColor(TFT_BLACK);
  tft.setFreeFont(FF18);
  tft.drawString("  Ozone AQI:    Particle AQI:",10,50);
  tft.drawString(stamp,60,110);
  tft.setFreeFont(FF18);
  tft.setTextColor(TFT_BLACK);
  tft.drawString("AQI",250,78);
  tft.drawString("AQI",100,78);  
  tft.fillRect(0, 40, 320, 2, TFT_BLACK);
  
  Serial.begin(115200);
  setup_wifi();
  client.setServer(mqttServer, 1883);  //set mqtt server
  client.setCallback(callback);
}

Main loop checks if connected, checks for MQTT messages and pushes latest line chart of sensor data to the LCD display

void loop() {
  // check if connected to mqtt
  if (!client.connected()) {
    reconnect();
  }
  if (msg == 1) {                         // check if new callback message
    
    msg = 0;                             // reset message flag
    Serial.print("decoded timestamp = ");
    Serial.println(stamp);
    Serial.print("decoded data1 = ");
    Serial.println(data1);
    Serial.print("decoded data2 = ");
    Serial.println(data2);

    // update line chart code
    // chart consists of two lines tracking values data1 and data2
    Serial.print("data[].size = ");
    Serial.println(data[0].size());  //debug - print data[] size for line chart
    if (data[0].size() == max_size) {
      for (uint8_t i = 0; i<2; i++){
        data[i].pop();              //this is used to remove the first read variable when max_size reached
      }
    }
    data[0].push(1.0 * data1);  //read variables and store in line chart data array
    data[1].push(1.0 * data2); 
//    Serial.println(data[0]);   //debug    

    spr.fillSprite(TFT_WHITE);  //clear line chart area
    
    //Settings for the line graph title
    auto header =  text( 0, 100)
                .value("test")
                .align(center)
                .valign(vcenter)
                .width(tft.width())
                .thickness(3);
 
    header.height(header.font_height() );
   // header.draw(); //Header is not used so disabled
    
    auto content = line_chart(20, header.height()-10); //(x,y) where the line graph begins
         content
                .height(tft.height() - 140) //header.height() * 1.5) //actual height of the line chart
                .width(tft.width() - 20) //actual width of the line chart
                .based_on(0.0) //Starting point of y-axis, must be a float
                .show_circle(false) //drawing a cirle at each point, default is on so set to false.
                .value({data[0], data[1]}) //passing through the data to line graph
                .color(TFT_PURPLE, TFT_BLUE) //Setting the color for each line
                .draw();
    
    spr.pushSprite(0, 130);  //display line chart
  }
  Serial.println("debug - in main loop");


  delay(2000);

  client.loop();

}

4 - Example Serial Monitor output from Arduino code

Various Print statements have been inserted in the example Arduino code to help during debug and code modifications. Example output is shown below.

5 - Latest source code for the WioTerminalMQTTDisplay2topicOAQrev2.ino application is on github at below link:

github.com

eewiki/machinechat/blob/master/Wio Terminal/WioTerminalMQTTDisplay2topicOAQrev2.ino

/*
 Wio Terminal MQTT data display example 
 filename: WioTerminalMQTTDisplay2topicOAQ.ino
 project based on WioTerminalMQTTDisplay.ino which is a sketch that demonstrates using the Wio Terminal to mqtt subscribe to air quality sensor data on the 
 machinechat JEDI One IoT data platform. It uses WiFi to connect to the JEDI One MQTT broker.
 Ozone air quality sensor data - Renesas
 Particle air quality sensor date - Panasonic
 11/10/2021 - this project takes sketch WioTerminalMQTTDisplay.ino and modifies to subscribe to 2 topics and changes topics to outdoor air quality sensors for 
 ozone and particulate matter to display AQI
 11/16/2021 - clean up code and change to version to "_rev1", also add 3rd subtopic for testing
 3/30/2022 - rev2 change back to subscribe to just two topics (comment out subtopic1
*/

#include <rpcWiFi.h>
#include <PubSubClient.h>
#include <TFT_eSPI.h>
#include "Free_Fonts.h"
#include"seeed_line_chart.h" //include the library

TFT_eSPI tft;

This file has been truncated. show original

Set up the JEDI One

1 - If machinechat JEDI One is not already installed on the Raspberry Pi see below:

Get Raspberry Pi version of JEDI One DK-JEDIONE-RP
Install on Pi, see Raspberry Pi - Installing JEDI One as a Service

2 - Set up the JEDI One as described in the referenced two projects First project is Machinechat with Renesas ZMOD4510 Outdoor Air Quality Sensor. Second project is Machinechat with Panasonic SN-GCJA5 Air Quality (PM) Sensor.

Example JEDI One air quality data screenshot.

Conclusion

Seeed’s Wio Terminal makes it easy to implement a low cost full color graphical remote MQTT data display for outdoor air quality. It’s built-in WiFi and associated Arduino libraries enable a direct connection to the JEDI One MQTT broker running on the Raspberry Pi. Machinechat’s JEDI One IoT data management provides MQTT access to any data it is collecting as well as additional processing, alerts or other actions.

References

Seeed - Wio Terminal Product Page
Seeed - Wio Terminal Wiki
Seeed - Wio Terminal LCD Linecharts
Seeed - Wio Terminal LCD Fonts
Getting Started with machinechat’s JEDI One IoT Platform
Arduino - How to use ArduinoJson with PubSubClient?
machinechat Product Guide - Built In MQTT Broker - Data Collector
machinechat Product Guide - MQTT Broker - Subscribing to a topic
HIVEMQ - MQTT Essentials
EPA - Ground-level Ozone Pollution website
EPA - Particulate Matter (PM) Pollution website