A self-hosted MQTT environment for Internet of Things – Part 2

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2019-06-22T13:56:50+02:00

Dear Sir, May I ask a question about the file to be included i.e. “WIFI_and_brocker_parameters.h” for what is this file for and where to get it? Appreciate your explanation.

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2019-06-24T06:47:04+02:00

At the bottom of the blog post, there is link to GitHub where the related code can be fetched. Specifically, the header-file exists here: https://github.com/LarsBergqvist/MQTT_IoT/tree/master/ESP8266_PubSub
The file contains constants that are specific for a local environment, WIFI-name, password etc, and you should change these values so that they match your own environment.

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	//
	// This is a minimal example on MQTT publish and subscribe from an ESP8266 board
	// to an MQTT broker (I have used a local Mosquitto running on a Raspberry Pi)
	// This example uses the PubSub client library (https://github.com/knolleary/pubsubclient)
	// Install it in the Arduino IDE before compiling the sketch

	#include <ESP8266WiFi.h>
	#include <PubSubClient.h>
	#include "WIFI_and_broker_parameters.h"

	#define CLIENT_NAME "ESP8266_1" // just a name to identify this client
	WiFiClient wifiClient;
	PubSubClient mqttClient(BROKER_IP,BROKER_PORT,wifiClient);

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

	mqttClient.setCallback(callback);

	WiFi.begin(WLAN_SSID, WLAN_PASS);

	connectToWiFiAndBroker();
	}

	void connectToWiFiAndBroker()
	{
	Serial.print("Connecting to WIFI");
	while (WiFi.status() != WL_CONNECTED)
	{
	Serial.print(".");
	delay(1000);
	}
	Serial.println("Connected to WIFI!");

	Serial.println("Connecting to broker");
	while (!mqttClient.connect(CLIENT_NAME))
	{
	Serial.print(".");
	delay(1000);
	}
	Serial.println("Connected to broker!");

	mqttClient.subscribe("InterestingTopics/#");
	}

	#define MILLISEC_DELAY_BETWEEN_PUBLISH 10000
	unsigned long lastTime = 0;
	unsigned long currentValue = 1;
	char msg[50];

	void loop()
	{
	if (!mqttClient.connected())
	{
	connectToWiFiAndBroker();
	}

	mqttClient.loop();

	if(millis() – lastTime > MILLISEC_DELAY_BETWEEN_PUBLISH)
	{
	lastTime = millis();
	Serial.println("Publishing a new value");
	snprintf (msg, 75, "%ld", currentValue);
	Serial.println(currentValue);
	mqttClient.publish("ESP8266/CurrentValue", msg);
	currentValue++;
	}
	}

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

	}

	//
	// This is an example on MQTT publish from an ESP8266 board
	// to an MQTT broker (I have used a local Mosquitto running on a Raspberry Pi)
	// This example uses the PubSub client library (https://github.com/knolleary/pubsubclient)
	// Install it in the Arduino IDE before compiling the sketch
	// Sensor values are fetched from an indoor DHT22 sensor and an outdoor DHT22 sensor


	#include <ESP8266WiFi.h>
	#include <PubSubClient.h>
	#include "WIFI_and_broker_parameters.h"

	//
	// WIFI and MQTT setup
	//
	#define CLIENT_NAME "GarageClient"
	WiFiClient wifiClient;
	PubSubClient mqttClient(BROKER_IP,BROKER_PORT,wifiClient);

	//
	// Sensor setup
	//
	#include <DHT.h>
	#define DHTPIN_OUTDOOR 4
	#define DHTTYPE_OUTDOOR DHT22
	DHT dht_outdoor(DHTPIN_OUTDOOR, DHTTYPE_OUTDOOR);
	#define DHTPIN_INDOOR 5
	#define DHTTYPE_INDOOR DHT22
	DHT dht_indoor(DHTPIN_INDOOR, DHTTYPE_INDOOR);



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

	WiFi.begin(WLAN_SSID, WLAN_PASS);

	dht_outdoor.begin();
	dht_indoor.begin();
	}

	#define SECONDS_BETWEEN_MEASUREMENTS 600
	unsigned long lastTime = 0;
	bool firstTime = true;

	void loop()
	{
	if ( firstTime \|\| (millis() – lastTime > SECONDS_BETWEEN_MEASUREMENTS*1000) )
	{
	firstTime = false;
	lastTime = millis();

	if (!mqttClient.connected())
	{
	connectToWiFiAndBroker();
	}

	mqttClient.loop();

	float h_outdoor = dht_outdoor.readHumidity();
	float t_outdoor = dht_outdoor.readTemperature();
	float h_indoor = dht_indoor.readHumidity();
	float t_indoor = dht_indoor.readTemperature();

	publishFloatValue(h_outdoor,"Home/Outdoor/Humidity");
	publishFloatValue(t_outdoor,"Home/Outdoor/Temperature");
	publishFloatValue(h_indoor,"Home/Garage/Humidity");
	publishFloatValue(t_indoor,"Home/Garage/Temperature");
	}
	}

	void connectToWiFiAndBroker()
	{
	Serial.print("Connecting to WIFI");
	while (WiFi.status() != WL_CONNECTED)
	{
	Serial.print(".");
	delay(1000);
	}
	Serial.println("Connected to WIFI!");

	Serial.println("Connecting to broker");
	while (!mqttClient.connect(CLIENT_NAME))
	{
	Serial.print(".");
	delay(1000);
	}
	Serial.println("Connected to broker!");
	}

	char msg[50];
	void publishFloatValue(float value, char* topic)
	{
	if (isnan(value))
	{
	Serial.println("Invalid value!");
	return;
	}

	Serial.println("Publishing a new value");
	ftoa(msg,value);
	Serial.println(msg);
	mqttClient.publish(topic, msg);
	}

	char ftoa(char buffer, float f)
	{
	char *returnString = buffer;
	long integerPart = (long)f;
	itoa(integerPart, buffer, 10);
	while (*buffer != '\0') buffer++;
	*buffer++ = '.';
	long decimalPart = abs((long)((f – integerPart) * 100));
	itoa(decimalPart, buffer, 10);
	return returnString;
	}

	void loop()
	{
	if ( firstTime \|\| (millis() – lastTime > SECONDS_BETWEEN_MEASUREMENTS*1000) )
	{
	firstTime = false;
	lastTime = millis();

	if (!mqttClient.connected())
	{
	connectToWiFiAndBroker();
	}

	mqttClient.loop();

	float h_indoor = dht_indoor.readHumidity();
	float t_indoor = dht_indoor.readTemperature();

	publishFloatValue(h_indoor,"Home/GroundFloor/Humidity");
	publishFloatValue(t_indoor,"Home/GroundFloor/Temperature");

	int moistureWarning = digitalRead(14);
	if (moistureWarning == 1)
	{
	mqttClient.publish("Home/GroundFloor/PlantStatus", "Please water the plant!");
	}
	else
	{
	mqttClient.publish("Home/GroundFloor/PlantStatus", "Plant is ok!");
	}
	}

	}

	import paho.mqtt.client as mqtt
	import datetime

	def on_connect(client, userdata, flags, rc):
	print("Connected with result code "+str(rc))
	client.subscribe("Home/#")

	def on_message(client, userdata, msg):
	print(str(datetime.datetime.now()) + ": " + msg.topic + " " + str(msg.payload))

	client = mqtt.Client()
	client.on_connect = on_connect
	client.on_message = on_message

	client.connect("192.168.1.16", 1883, 60)

	client.loop_forever()

A self-hosted MQTT environment for Internet of Things – Part 2

MQTT client libraries for Arduino

The PubSub client library

Setting up a real environment with sensors

Setting up the garage ESP8266 board

Setting up the groundfloor ESP8266 board

Setting up the subscriber

Next step

Published by Lars

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