RSS #20 Demo IoT in Action Using MQTT

temptron.ino

/**
* Written by [email protected]
* 28 March 2021
* To use this script you should using ESP32, DHT22 sensor and LCD SSD1306
* Please comment when you got any issue
*/

#include <WiFi.h>
#include <PubSubClient.h>
#include "DHT.h"
#include "SSD1306Wire.h"
#include <ArduinoJson.h>

#define DHTPIN 15     // what digital pin the DHT22 is conected to
#define DHTPIN2 23
#define DHTTYPE DHT22   // There are multiple kinds of DHT sensors

DHT dht(DHTPIN, DHTTYPE);
DHT dht2(DHTPIN2, DHTTYPE);
SSD1306Wire  display(0x3c, 18, 19);

// WiFi credentials.
const char* WIFI_SSID = "";
const char* WIFI_PASS = "";

// Broker
const char* mqtt_server = "";

WiFiClient wifiClient;
PubSubClient client(wifiClient);

float temperature=0, suhu = 0;
float humidity=0, lembab = 0;

const int ledPin = 4;

long lastMsg = 0;
char msg[50];
int value = 0;
String mac;

void setup() {
  Serial.begin(9600);

  dht.begin();
  dht2.begin();
  
  setup_wifi();
  client.setServer(mqtt_server, 1883);
  client.setCallback(callback);

  pinMode(ledPin, OUTPUT);

  display.init();
  display.flipScreenVertically();
  display.setFont(ArialMT_Plain_16);
}

void setup_wifi() {
  delay(10);
  // We start by connecting to a WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(WIFI_SSID);

  WiFi.begin(WIFI_SSID, WIFI_PASS);

  mac = WiFi.macAddress();
  mac.replace(":", "");
  mac.toLowerCase();

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }

  Serial.println("");
  Serial.println("WiFi connected");
  Serial.println("IP address: ");
  Serial.println(WiFi.localIP());
}

void callback(char* topic, byte* message, unsigned int length) {
  Serial.print("Message arrived on topic: ");
  Serial.print(topic);
  Serial.print(". Message: ");
  String messageTemp;
  
  for (int i = 0; i < length; i++) {
    Serial.print((char)message[i]);
    messageTemp += (char)message[i];
  }
  Serial.println();

  // Feel free to add more if statements to control more GPIOs with MQTT

  // If a message is received on the topic esp32/output, you check if the message is either "on" or "off". 
  // Changes the output state according to the message
  if (String(topic) == "temptron/output") {
    Serial.print("Changing output to ");
    if(messageTemp == "on"){
      Serial.println("on");
      digitalWrite(ledPin, HIGH);
    }
    else if(messageTemp == "off"){
      Serial.println("off");
      digitalWrite(ledPin, LOW);
    }
  }
}

void reconnect() {
  // Loop until we're reconnected
  while (!client.connected()) {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect("ESP8266Client")) {
      Serial.println("connected");
      // Subscribe
      client.subscribe("temptron/output");
    } else {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}

void loop() {
  char tempString[8];
  char humString[8];
  char suhuString[8];
  char lembabString[8];
  if (!client.connected()) {
    reconnect();
  }
  client.loop();

  long now = millis();
  if (now - lastMsg > 5000) {
    lastMsg = now;
    
    // Temperature in Celsius
    temperature = dht.readTemperature();
    // Uncomment the next line to set temperature in Fahrenheit 
    // (and comment the previous temperature line)
    //temperature = 1.8 * bme.readTemperature() + 32; // Temperature in Fahrenheit
    suhu = dht2.readTemperature();
    
    // Convert the value to a char array
    // char tempString[8];
    dtostrf(temperature, 1, 2, tempString);
    dtostrf(suhu, 1, 2, suhuString);
    Serial.print("Temperature: ");
    Serial.println(tempString);

    humidity = dht.readHumidity();
    lembab = dht2.readHumidity();
    
    // Convert the value to a char array
    // char humString[8];
    dtostrf(humidity, 1, 2, humString);
    dtostrf(lembab, 1, 2, lembabString);
    Serial.print("Humidity: ");
    Serial.println(humString);

    StaticJsonBuffer<500> jsonBuffer;
    JsonObject& root = jsonBuffer.createObject();
    JsonObject& data = jsonBuffer.createObject();
    data["tempA"] = temperature;
    data["tempB"] = suhu;
    data["humidityA"] = humidity;
    data["humidityB"] = lembab;
    root["data"] = data;
    root["deviceId"] = mac;
    char buffer[200];
    root.printTo(buffer);
    client.publish("temptron/json", buffer);
    
    String deviceTopic = mac + "/state";
    char topic[20];
    deviceTopic.toCharArray(topic, 20);
    client.publish(topic, buffer);
    
  }

  drawFontFaceDemo(tempString, humString, suhuString, lembabString);

}

void drawFontFaceDemo(char *temp, char *hum, char *suhu, char *lembab) {
  //char *degree = "C";
  // clear the display
  display.clear();
    // Font Demo1
    // create more fonts at http://oleddisplay.squix.ch/
    display.drawRect(0, 0, 128, 48);
    display.drawLine(0, 16, 128, 16);
    display.drawLine(64, 0, 64, 47);
    display.drawRect(0, 64, 64, 34);
    display.setTextAlignment(TEXT_ALIGN_LEFT);
    display.setFont(ArialMT_Plain_16);
    
    // HEADER
    display.fillRect(0,0,128,16);
    display.setColor(BLACK);
    display.drawString(7, 0, "ATAS");
    display.drawString(66, 0, "BAWAH");
    
    
    display.setColor(WHITE);
    // ATAS
    display.drawString(3, 15, temp);
    display.drawString(48, 15, "C");
    display.drawString(3, 31, hum);
    display.drawString(48, 31, "%");
    // BAWAH
    display.drawString(67, 15, suhu);
    display.drawString(110, 15, "C");
    display.drawString(67, 31, lembab);
    display.drawString(110, 31, "%");
  // write the buffer to the display
  // display.fillRect(0,48,128,16);
  display.display();
}