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Sketch for the ESP8266 to publish temperature and humidity values received from a DHT22 to MQTT
// Get ESP8266 going with Arduino IDE
// - https://github.com/esp8266/Arduino#installing-with-boards-manager
// Required libraries (sketch -> include library -> manage libraries)
// - PubSubClient by Nick ‘O Leary
// - DHT sensor library by Adafruit
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
#include <DHT.h>
#define wifi_ssid "YOUR WIFI SSID"
#define wifi_password "WIFI PASSWORD"
#define mqtt_server "YOUR_MQTT_SERVER_HOST"
#define mqtt_user "your_username"
#define mqtt_password "your_password"
#define humidity_topic "sensor/humidity"
#define temperature_topic "sensor/temperature"
#define DHTTYPE DHT22
#define DHTPIN 14
WiFiClient espClient;
PubSubClient client(espClient);
DHT dht(DHTPIN, DHTTYPE, 11); // 11 works fine for ESP8266
void setup() {
Serial.begin(115200);
dht.begin();
setup_wifi();
client.setServer(mqtt_server, 1883);
}
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_password);
while (WiFi.status() != WL_CONNECTED) {
delay(500);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi connected");
Serial.println("IP address: ");
Serial.println(WiFi.localIP());
}
void reconnect() {
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Attempt to connect
// If you do not want to use a username and password, change next line to
// if (client.connect("ESP8266Client")) {
if (client.connect("ESP8266Client", mqtt_user, mqtt_password)) {
Serial.println("connected");
} else {
Serial.print("failed, rc=");
Serial.print(client.state());
Serial.println(" try again in 5 seconds");
// Wait 5 seconds before retrying
delay(5000);
}
}
}
bool checkBound(float newValue, float prevValue, float maxDiff) {
return !isnan(newValue) &&
(newValue < prevValue - maxDiff || newValue > prevValue + maxDiff);
}
long lastMsg = 0;
float temp = 0.0;
float hum = 0.0;
float diff = 1.0;
void loop() {
if (!client.connected()) {
reconnect();
}
client.loop();
long now = millis();
if (now - lastMsg > 2000) {
lastMsg = now;
float newTemp = dht.readTemperature();
float newHum = dht.readHumidity();
if (checkBound(newTemp, temp, diff)) {
temp = newTemp;
Serial.print("New temperature:");
Serial.println(String(temp).c_str());
client.publish(temperature_topic, String(temp).c_str(), true);
}
if (checkBound(newHum, hum, diff)) {
hum = newHum;
Serial.print("New humidity:");
Serial.println(String(hum).c_str());
client.publish(humidity_topic, String(hum).c_str(), true);
}
}
}

DHT library seemingly has changed since you wrote this.....getting this error:
/Arduino/libraries/DHT_sensor_library/DHT_U.h:25:29: fatal error: Adafruit_Sensor.h: No such file or directory
#include <Adafruit_Sensor.h>

                         ^

compilation terminated.
exit status 1
Error compiling for board SparkFun ESP8266 Thing.

h00s commented Jan 24, 2017

@john3exonets problem you experiencing was introduced in dht library version 1.3.0. Install version 1.2.3 and it will work ok!

He guys,

on question.

I flashed the sketch on a nodemcu, the serial monitor keeps saying:

Attempting MQTT connection...connected
Attempting MQTT connection...connected
Attempting MQTT connection...connected
Attempting MQTT connection...connected
Attempting MQTT connection...connected
Attempting MQTT connection...connected
Attempting MQTT connection...connected
Attempting MQTT connection...connected

Whats the problem?

I have one older sensor with the same sketch just working fine (flashed it 3 months ago)
BR

Lukas

@ballob i have this error:

C:\Users\Paula Alves\Desktop\dddddd\dddddd.ino: In function 'void setup()':

dddddd:32: error: 'class PubSubClient' has no member named 'setServer'

client.setServer(mqtt_server, 1883);

      ^

C:\Users\Paula Alves\Desktop\dddddd\dddddd.ino: In function 'void reconnect()':

dddddd:62: error: no matching function for call to 'PubSubClient::connect(const char [14], const char [14], const char [14])'

 if (client.connect("ESP8266Client", mqtt_user, mqtt_password)) {

                                                             ^

C:\Users\Paula Alves\Desktop\dddddd\dddddd.ino:62:65: note: candidates are:

In file included from C:\Users\Paula Alves\Desktop\dddddd\dddddd.ino:8:0:

C:\Users\Paula Alves\Documents\Arduino\libraries\pubsubclient-master\src/PubSubClient.h:111:9: note: bool PubSubClient::connect(String)

bool connect(String id);

     ^

C:\Users\Paula Alves\Documents\Arduino\libraries\pubsubclient-master\src/PubSubClient.h:111:9: note: candidate expects 1 argument, 3 provided

C:\Users\Paula Alves\Documents\Arduino\libraries\pubsubclient-master\src/PubSubClient.h:123:9: note: bool PubSubClient::connect(String, String, uint8_t, bool, String)

bool connect(String id, String willTopic, uint8_t willQos, bool willRetain, String willMessage);

     ^

C:\Users\Paula Alves\Documents\Arduino\libraries\pubsubclient-master\src/PubSubClient.h:123:9: note: candidate expects 5 arguments, 3 provided

C:\Users\Paula Alves\Documents\Arduino\libraries\pubsubclient-master\src/PubSubClient.h:185:9: note: bool PubSubClient::connect(MQTT::Connect&)

bool connect(MQTT::Connect &conn);

     ^

C:\Users\Paula Alves\Documents\Arduino\libraries\pubsubclient-master\src/PubSubClient.h:185:9: note: candidate expects 1 argument, 3 provided

dddddd:66: error: 'class PubSubClient' has no member named 'state'

   Serial.print(client.state());

                       ^

C:\Users\Paula Alves\Desktop\dddddd\dddddd.ino: In function 'void loop()':

dddddd:101: error: invalid conversion from 'const char*' to 'const uint8_t* {aka const unsigned char*}' [-fpermissive]

   client.publish(temperature_topic, String(temp).c_str(), true);

                                                        ^

In file included from C:\Users\Paula Alves\Desktop\dddddd\dddddd.ino:8:0:

C:\Users\Paula Alves\Documents\Arduino\libraries\pubsubclient-master\src/PubSubClient.h:144:9: error: initializing argument 2 of 'bool PubSubClient::publish(String, const uint8_t*, uint32_t, bool)' [-fpermissive]

bool publish(String topic, const uint8_t *payload, uint32_t plength, bool retained = false);

     ^

dddddd:108: error: invalid conversion from 'const char*' to 'const uint8_t* {aka const unsigned char*}' [-fpermissive]

   client.publish(humidity_topic, String(hum).c_str(), true);

                                                    ^

In file included from C:\Users\Paula Alves\Desktop\dddddd\dddddd.ino:8:0:

C:\Users\Paula Alves\Documents\Arduino\libraries\pubsubclient-master\src/PubSubClient.h:144:9: error: initializing argument 2 of 'bool PubSubClient::publish(String, const uint8_t*, uint32_t, bool)' [-fpermissive]

bool publish(String topic, const uint8_t *payload, uint32_t plength, bool retained = false);

     ^

exit status 1
'class PubSubClient' has no member named 'setServer'

errece commented Oct 12, 2017

Yes, that's perfect, but I don't know how to implement it with HomeAssistant Generic Thermostat, it requires a float, and don't know how change the code to do that...

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