I, Stonez56, also known as Kevin Chen, am a tech enthusiast based in Hsinchu, Taiwan. I’m known for my work in Arduino, IoT, app development, and more. My YouTube channel and blog are platforms where I share my knowledge and projects. I’ve also developed an online tool for generating U8g2 UTF8 font codes for Arduino projects. My work is educational, aimed at helping others learn and implement technology in their own projects. Visit stonez56.blogspot.com
/*
Basic ESP8266 MQTT example
This sketch demonstrates the capabilities of the pubsub library in combination
with the ESP8266 board/library.
It connects to an MQTT server then:
- publishes "hello world" to the topic "outTopic" every two seconds
- subscribes to the topic "inTopic", printing out any messages
it receives. NB - it assumes the received payloads are strings not binary
- If the first character of the topic "inTopic" is an 1, switch ON the ESP Led,
else switch it off
It will reconnect to the server if the connection is lost using a blocking
reconnect function. See the 'mqtt_reconnect_nonblocking' example for how to
achieve the same result without blocking the main loop.
To install the ESP8266 board, (using Arduino 1.6.4+):
- Add the following 3rd party board manager under "File -> Preferences -> Additional Boards Manager URLs":
http://arduino.esp8266.com/stable/package_esp8266com_index.json
- Open the "Tools -> Board -> Board Manager" and click install for the ESP8266"
- Select your ESP8266 in "Tools -> Board"
*/
#include <WiFi.h>
#include <PubSubClient.h>
#include <EasyButton.h>
#define LED 2 //built-in LED on ESP32
#include "DHT.h"
#define DHTPIN 23 // Digital pin connected to the DHT sensor
#define DHTTYPE DHT11 // DHT11
DHT dht(DHTPIN, DHTTYPE); // Initialize DHT sensor.
// Set up the temp / humidity update cycle
const int updateCycle = 5000;
// Update these with values suitable for your network.
const char *ssid = "Wi-Fi SSID";
const char *password = "Wi-Fi Password";
// Define your client ID on EMQX
String mqtt_ClientID = "stonez56_IOT_Station_";
// Define your topics to subscribe / publish
const char* sub_topic = "stonez56/esp32s";
const char* pub_led_topic = "stonez56/esp32s_led_state";
const char* pub_init_topic = "stonez56/esp32s_is_back";
const char* pub_temp_topic = "stonez56/esp32s_temp";
const char* pub_humd_topic = "stonez56/esp32s_humd";
// EMQX broker parameters
const char *mqtt_server = "broker.emqx.io";
const char *mqtt_userName = "emqx";
const char *mqtt_password = "public";
WiFiClient espClient;
PubSubClient client(espClient);
unsigned long lastMsg = 0;
#define MSG_BUFFER_SIZE (50)
char msg[MSG_BUFFER_SIZE];
char msg1[MSG_BUFFER_SIZE];
int value = 0;
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, password);
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());
}
void callback(char *topic, byte *payload, unsigned int length)
{
Serial.print("Message arrived [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++)
{
Serial.print((char)payload[i]);
}
Serial.println();
payload[length] = '\0';
String message = (char *)payload;
if (strcmp(topic, sub_topic) == 0)
{
if (message == "off")
{
digitalWrite(LED, LOW); //Turn off
client.publish(pub_led_topic, "off");
}
if (message == "on")
{
digitalWrite(LED, HIGH); //Turn on
client.publish(pub_led_topic, "on");
}
}
/* Switch on the LED if an 1 was received as first character
// if ((char)payload[0] == '1')
// {
// digitalWrite(BUILTIN_LED, LOW); // Turn the LED on (Note that LOW is the voltage level
// // but actually the LED is on; this is because
// // it is active low on the ESP-01)
// }
// else
// {
// digitalWrite(BUILTIN_LED, HIGH); // Turn the LED off by making the voltage HIGH
// } */
}
void reconnect()
{
// Loop until we're reconnected
while (!client.connected())
{
Serial.println("Attempting EMQX MQTT connection...");
// Create a random client ID
mqtt_ClientID += String(random(0xffff), HEX);
// Attempt to connect
if (client.connect((mqtt_ClientID, mqtt_userName, mqtt_password)))
{
Serial.print(" connected with Client ID: ");
Serial.println(mqtt_ClientID);
// Once connected, publish an announcement...
client.publish(pub_init_topic, "Hi, I'm online!");
// ... and resubscribe
client.subscribe(sub_topic);
}
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()
{
//Start DH11 sensor
dht.begin();
pinMode(LED, OUTPUT); // Initialize the _LED pin as an output
digitalWrite(LED, LOW); //default ESP32 LOW is turn off
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
}
void loop()
{
if (!client.connected())
{
reconnect();
}
client.loop();
unsigned long now = millis();
if (now - lastMsg > updateCycle)
{
lastMsg = now;
float humidity = dht.readHumidity();
float temperature = dht.readTemperature();
// Check if any reads failed and exit early (to try again).
if (isnan(humidity) || isnan(temperature))
{
Serial.println(F("Failed to read from DHT sensor!"));
return;
}else{ // publish the message
snprintf(msg, MSG_BUFFER_SIZE, "%.1lf°", temperature);
snprintf(msg1, MSG_BUFFER_SIZE,"%.0lf%%", humidity);
Serial.print("Publish message: ");
Serial.println(msg);
client.publish(pub_temp_topic, msg);
client.publish(pub_humd_topic, msg1);
}
}
}
