ESP32. MQTT. Broker. Publish. Subscribe. ThingSpeak

Juan_Antonio · June 6, 2020, 9:35pm

5.- Slider.

Juan_Antonio · June 6, 2020, 9:37pm

6.- App Inventor Subscribe to juan/aleatorio and Publish juan/boton.

p117B_mqtt_Extension.aia (74.0 KB)

Code for ESP32 is the same as example: 4.- Now the two codes united.

Broker: broker.hivemq.com
Port: 1883

ESP32 Publish: juan/aleatorio
ESP32 Subscribe: juan/boton

App Inventor Publish: juan/boton
App Inventor Subscribe: juan/aleatorio

App Inventor.

We will use this great extension:
https://ullisroboterseite.de/android-AI2-MQTT-en.html

Juan_Antonio · June 7, 2020, 12:28pm

7.- App on/off LED12 and LED14 of ESP32. App checks status LED12 and LED14.

p117B_mqtt_Extension_Btn_LED.aia (74.8 KB)

App Publish boton12 and boton14, and on/off LED12 and LED14
ESP32 Subscripted to boton12 and boton14 Publish status LEDs

Broker: broker.hivemq.com
Port: 1883

App Inventor Publish: juan/boton12
App Inventor Publish: juan/boton14
App Inventor Subscribe: juan/led12_status
App Inventor Subscribe: juan/led14_status
App Inventor Subscribe: juan/led12_led14_status

ESP32 Publish: juan/led12_status
ESP32 Publish: juan/led14_status
ESP32 Publish: juan/led12_led14_status
ESP32 Subscribe: juan/boton12
ESP32 Subscribe: juan/boton14

// Juan A. Villalpando.
// http://kio4.com/arduino/117_Wemos_MQTT.htm

//#include <ESP8266WiFi.h> // Para el ESP8266
#include <WiFi.h> // Para el ESP32
WiFiClient WIFI_CLIENT;
#include <PubSubClient.h>
PubSubClient MQTT_CLIENT;

const char* ssid = "Nombre_Red_WiFi";
const char* password = "Clave_Wifi";

#define LED12 12 // LED12 ESP32
#define LED14 14 // LED14 ESP32
String LED12_status = "- ? -";
String LED14_status = "- ? -";
String LED12_LED14_status = "- ? -";

void setup() {
  pinMode(LED12, OUTPUT);
  pinMode(LED14, OUTPUT);
  Serial.begin(115200);
  delay(10);
  Serial.println();
  Serial.print("Connecting with ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

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

Serial.println("");
Serial.print("WiFi conected. IP: ");
Serial.println(WiFi.localIP());

// Setting Callback.
  MQTT_CLIENT.setCallback(callback);
}

// What to do when it receives the data. 
void callback(char* recibido, byte* payload, unsigned int length) {
  Serial.print("Message received: ");
  Serial.print(recibido);
  Serial.print("   ");

  for (int i=0;i<length;i++) {
    char receivedChar = (char)payload[i];
    Serial.println(receivedChar);
  if (receivedChar == '1') {digitalWrite(LED12, HIGH);}
  if (receivedChar == '2') {digitalWrite(LED12, LOW);}
  if (receivedChar == '3') {digitalWrite(LED14, HIGH);}
  if (receivedChar == '4') {digitalWrite(LED14, LOW);}

    if (digitalRead(LED12) == HIGH) {LED12_status = "LED12 ON";} else {LED12_status = "LED12 OFF";}
    if (digitalRead(LED14) == HIGH) {LED14_status = "LED14 ON";} else {LED14_status = "LED14 OFF";}
    LED12_LED14_status = LED12_status + " and " + LED14_status; 
  }
}
 
void loop() {
  if (!MQTT_CLIENT.connected()) {
    reconnect();
  }

  // PUBLISH topic.
// Convierte el entero a char. Debe ser char.
char led12_st[10];
char led14_st[10];
char led12_led14_st[25];
LED12_status.toCharArray(led12_st, 10);
LED14_status.toCharArray(led14_st, 10);
LED12_LED14_status.toCharArray(led12_led14_st, 25);

MQTT_CLIENT.publish("juan/led12_status", led12_st);
  delay(1000);
MQTT_CLIENT.publish("juan/led14_status", led14_st);
  delay(1000);
MQTT_CLIENT.publish("juan/led12_led14_status", led12_led14_st);
  delay(1000);
  
  MQTT_CLIENT.loop(); // Check Subscription.

}

// Reconecta con MQTT broker
void reconnect() {
MQTT_CLIENT.setServer("broker.hivemq.com", 1883);  
//MQTT_CLIENT.setServer("mqtt.eclipse.org", 1883);
MQTT_CLIENT.setClient(WIFI_CLIENT);

// Trying connect with broker.
while (!MQTT_CLIENT.connected()) {
Serial.println("Trying to connect with Broker MQTT.");
MQTT_CLIENT.connect("JuanAntonio"); // it isn't necessary..
MQTT_CLIENT.subscribe("juan/boton12"); // HERE SUBSCRIBE.
MQTT_CLIENT.subscribe("juan/boton14"); // HERE SUBSCRIBE.

// Wait to try to reconnect again...
delay(3000);
}

Serial.println("Conectado a MQTT.");
}

Juan_Antonio · June 7, 2020, 4:56pm

8.- App Inventor Publish a text.

p117B_mqtt_Extension_Texto.aia (73.5 KB)

App Publish a text: “Set LED12 ON”, “Set LED12 OFF”,…

// Juan A. Villalpando.
// http://kio4.com/arduino/117_Wemos_MQTT.htm

//#include <ESP8266WiFi.h> // Para el ESP8266
#include <WiFi.h> // Para el ESP32
WiFiClient WIFI_CLIENT;
#include <PubSubClient.h>
PubSubClient MQTT_CLIENT;

const char* ssid = "Nombre_Red_Wifi";
const char* password = "Clave_Wifi";

#define LED12 12 // LED12 ESP32
#define LED14 14 // LED14 ESP32
String message = "";

void setup() {
  pinMode(LED12, OUTPUT);
  pinMode(LED14, OUTPUT);
  Serial.begin(115200);
  delay(10);
  Serial.println();
  Serial.print("Connecting with ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

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

Serial.println("");
Serial.print("WiFi conected. IP: ");
Serial.println(WiFi.localIP());

// Setting Callback.
  MQTT_CLIENT.setCallback(callback);
}

// What to do when it receives the data. 
void callback(char* recibido, byte* payload, unsigned int length) {
  Serial.print("Message received: ");
  Serial.print(recibido);
  Serial.print("   ");
  message = "";
  for (int i=0;i<length;i++) {
    message += (char)payload[i];
  }
   Serial.println(message);
   if (message == "Set LED12 ON") {digitalWrite(LED12, HIGH);}
   if (message == "Set LED12 OFF") {digitalWrite(LED12, LOW);}
   if (message == "Set LED14 ON") {digitalWrite(LED14, HIGH);}
   if (message == "Set LED14 OFF") {digitalWrite(LED14, LOW);}
}
 
void loop() {
  if (!MQTT_CLIENT.connected()) {
    reconnect();
  }

  // PUBLISH topic.
  // Does not Publish.
  
  MQTT_CLIENT.loop(); // Check Subscription.

}

// Reconecta con MQTT broker
void reconnect() {
MQTT_CLIENT.setServer("broker.hivemq.com", 1883);  
//MQTT_CLIENT.setServer("mqtt.eclipse.org", 1883);
MQTT_CLIENT.setClient(WIFI_CLIENT);

// Trying connect with broker.
while (!MQTT_CLIENT.connected()) {
Serial.println("Trying to connect with Broker MQTT.");
MQTT_CLIENT.connect("JuanAntonio"); // it isn't necessary..
MQTT_CLIENT.subscribe("juan/boton12"); // HERE SUBSCRIBE.
MQTT_CLIENT.subscribe("juan/boton14"); // HERE SUBSCRIBE.

// Wait to try to reconnect again...
delay(3000);
}

Serial.println("Conectado a MQTT.");
}

Juan_Antonio · June 7, 2020, 5:59pm

9.- App Publish and moves a Servo in ESP32.

p117B_mqtt_Extension_Servo.aia (73.6 KB)

Publish juan/mensaje = “increases” —> increases grado +5
Publish juan/mensaje = “decreases” —> decreases grado -5
Publish juan/mensaje = 90* —> Move Servo to those position

// Juan A. Villalpando.
// http://kio4.com/arduino/117_Wemos_MQTT.htm

//#include <ESP8266WiFi.h> // Para el ESP8266
#include <WiFi.h> // Para el ESP32
WiFiClient WIFI_CLIENT;
#include <PubSubClient.h>
PubSubClient MQTT_CLIENT;

const char* ssid = "Nombre_Red_Wifi";
const char* password = "Clave_Wifi";

// Servo.
#include <Servo.h>
Servo myservo;
#define servoPin  27 // El servo en pin 27
int grado = 90;
String message = "";

void setup() {
  Serial.begin(115200);
  delay(10);
  myservo.attach(servoPin);
  Serial.println();
  Serial.print("Connecting with ");
  Serial.println(ssid);

  WiFi.begin(ssid, password);

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

Serial.println("");
Serial.print("WiFi conected. IP: ");
Serial.println(WiFi.localIP());

// Setting Callback.
  MQTT_CLIENT.setCallback(callback);
}

// What to do when it receives the data. 
void callback(char* recibido, byte* payload, unsigned int length) {
  Serial.print("Message received: ");
  Serial.print(recibido);
  Serial.print("   ");
  message = "";
  for (int i=0;i<length;i++) {
    message += (char)payload[i];
  }
   Serial.println(message);
   if (message == "increases") {grado = grado + 5; myservo.write(grado);}
   if (message == "decreases") {grado = grado - 5; myservo.write(grado);}
   if (message.indexOf("*") != -1)  { // if message contain *
   message = message.substring(0, message.length() - 1); // Delete last char *
   grado = message.toInt();
   myservo.write(grado);
   }
}
 
void loop() {
  if (!MQTT_CLIENT.connected()) {
    reconnect();
  }

  // PUBLISH topic.
  // Does not Publish.
  
  MQTT_CLIENT.loop(); // Check Subscription.

}

// Reconecta con MQTT broker
void reconnect() {
MQTT_CLIENT.setServer("broker.hivemq.com", 1883);  
//MQTT_CLIENT.setServer("mqtt.eclipse.org", 1883);
MQTT_CLIENT.setClient(WIFI_CLIENT);

// Trying connect with broker.
while (!MQTT_CLIENT.connected()) {
Serial.println("Trying to connect with Broker MQTT.");
MQTT_CLIENT.connect("JuanAntonio"); // it isn't necessary..
MQTT_CLIENT.subscribe("juan/mensaje"); // HERE SUBSCRIBE.

// Wait to try to reconnect again...
delay(3000);
}

Serial.println("Conectado a MQTT.");
}

It is convenient that the Servo is powered by an external power supply.

Juan_Antonio · June 7, 2020, 8:58pm

10.- Mobile chat.

p117B_mqtt_Extension_Chat.aia (73.8 KB)

This is a similar chat with CloudDB or FireBaseDB.

oooooooooooooo000oooooooooooooo

You can also send messages online.
http://www.hivemq.com/demos/websocket-client/

Juan_Antonio · June 8, 2020, 10:36am

11.- ThingSpeak Broker. ESP32 uploads random numbers to ThingSpeak.

It is necessary to register with an email account: ThingSpeak.
For users of the free option, the message update interval limit remains limited at 15 seconds.
New Channel.
Field1 = aleatorio.

ESP32 generates a random number every 15 seconds and uploads it to ThingSpeak.
Library ThingSpeak.
Sketch / Include Library / Manage Libraries… ThingSpeak

esp32_thingspeak813×548 28.3 KB

// Juan A. Villalpando.
// http://kio4.com/arduino/117_Wemos_MQTT.htm

// #include <ESP8266WiFi.h> // Para ESP8266
#include <WiFi.h> // Para ESP32
WiFiClient WIFI_CLIENT;
#include <ThingSpeak.h>

const char* ssid = "Nombre_de_tu_Red_Wifi";
const char* password = "Clave_Wifi";  

unsigned long Channel_ID = 746330;
const char * WriteAPIKey = "SVRKZNDDNS9TÑÑÑÑ";
unsigned long tiempo_actual = 0;

void setup() {
  Serial.begin(115200);

  WiFi.mode(WIFI_STA);   
  ThingSpeak.begin(WIFI_CLIENT);

  Serial.println();
  Serial.print("Connecting with ");
  Serial.println(ssid);
 
  WiFi.begin(ssid, password);
 
  while (WiFi.status() != WL_CONNECTED) {
  delay(500);
  Serial.print(".");
  }
  
  Serial.println("");
  Serial.print("WiFi conected. IP: ");
  Serial.println(WiFi.localIP());
}

void loop() {
  if((millis()-tiempo_actual)>= 16000){ // Each 16 seconds upload.
          int alea = random(0,90);
          tiempo_actual = millis();
          // Send alea to field1.
          int x = ThingSpeak.writeField(Channel_ID, 1, alea, WriteAPIKey);
          if(x == 200){ Serial.println("Upload correct: " + String(alea));}
          else{ Serial.println("Upload failed: " + String(alea)); }
  }
}

Juan_Antonio · June 8, 2020, 10:41am

12.- From App Inventor on/off a Lamp in ThingSpeak.

Remember: updates are every 15 seconds or more.

This example does not use ESP32.

Channel Settings / Field2 --> lamp
Add Widgets --> Lamp

Juan_Antonio · June 8, 2020, 11:25am

13.- App Inventor sends a number to ThingSpeak and gets last value. WebViewer.

Remember: updates are every 15 seconds or more.

p117_thingspeak_valor.aia (3.2 KB)

Create field3.
App Inventor sends values to field3.

esp32_thing20800×569 169 KB

esp32_thing22

Get last value:
https://api.thingspeak.com/channels/746330/fields/field3/last
Show WebViewer:
https://thingspeak.com/channels/746330/charts/1?&results=60&dynamic=true
Show all data in Json:
https://api.thingspeak.com/channels/746330/feeds.json
Show 6 last data in Json:
https://api.thingspeak.com/channels/746330/feeds.json?results=6
Show all data field1 in Json:
https://api.thingspeak.com/channels/746330/fields/1.json

Juan_Antonio · June 8, 2020, 4:40pm

14.- App Inventor Publish, sends values by Extension to ThingSpeak.

Now with extension.
Subscribe doesn’t work for me.

Subscribe: channels/Channel ID/subscribe/fields/field1/ReadAPIKey

Publish: channels/Channel ID/publish/fields/field1/WriteAPIKey

last value: https://api.thingspeak.com/channels/746330/fields/field1/last

Juan_Antonio · June 8, 2020, 5:39pm

15.- Others Dashboards.

https://mydevices.com/cayenne/signup/

https://accounts.adafruit.com/settings/profile

http://www.hivemq.com/demos/websocket-client/

MQTTLens Google Chrome Web Store
If you are a fan of Raspberry Pi, install mosquitto broker.
https://randomnerdtutorials.com/how-to-install-mosquitto-broker-on-raspberry-pi/
http://kio4.com/raspberry/16_mosquitto.htm

Luciano_De_Leon_Mene · September 7, 2020, 11:57pm

great job
muy buena explicacion de todo, hice unas pruebas con cloudmqtt con un wemos d1 esp8266 y funciona perfecto todo.
la extension es muy buena.
gracias por toda la informacion.

Juan_Antonio · April 30, 2021, 9:56pm

16.- Basic example of Subscribe and Publish to HiveMQ.

Normally MQTT is used in IoT, example: a sensor in a hardware sends a short message to a Broker and in real time an app receives it, or an app sends a short message to a Broker and this information is received by a hardware that performs a certain function.

We are going to see a basic example of Publish and Subscribe in the HiveMQ Broker.
We will not use hardware, only the application and the Broker.

Do this example! No registration required.

https://www.hivemq.com/

p117B_mqtt_Extension_Hivemq.aia (73.6 KB)

Juan_Antonio · May 5, 2021, 3:07pm

17.- Example with Slider.

p117Bi_mqtt_Extension_Hivemq_Slider.aia (83.7 KB)

We create the same Topic in Publish and Subscriptions: juan/Slider

mqtt19900×650 82.2 KB
We set two Sliders, Publish and Subscribe the same topic: juan/Slider

mqtt20578×935 59.9 KB
The first Slider sends the information directly. The second Slider uses the SliderTools extension and will send the value when "TouchUp".
The information will travel in "go and return".
We observe that the information "sends" and "receives" quite fast.
Extension SliderTools by @WatermelonIce
[FREE / Open Source] SliderTools - Bit of useful feature for sliders

Juan_Antonio · July 17, 2021, 1:45pm

18 .- AccelerometerSensor Publish and Subscribe x, y, z. Send and receive the three variables. HiveMQ.

p117B_mqtt_Extension_Hivemq_Acele.aia (72.0 KB)

AcceleratorSensor "Publish" in HiveMQ xAccel,yAccel,zAccel with topic: juan/acelerometer
and "Subscribe" juan/acelerometer, receive: xAccel,yAccel,zAccel

frdsir777 · December 23, 2021, 4:42am

why port at hivemq not same with port at mit app?
if i write at hivemq, host : broker.hivemq.com. , at mit app must be broker: broker.hivemq.com . it right?

the topic at publish should be title that my project right?

Juan_Antonio · December 23, 2021, 9:57am

https://www.hivemq.com/public-mqtt-broker/

Moh_Khafil_A · July 6, 2022, 2:08pm

please help me how to get updated data on mqtt server
Hello friend I'm studying the mqtt protocol
my project is to turn the room lights on and off with every button publish and subscribe
publish to send data values and subscribe to receive data but there is a problem when the application is disconnected with the subscriber data broker not being successfully updated
if anyone in the mqtt extension can request a request to the broker to update the missed data, I really need advice. thanks

I use the following extension
Ullis Roboter Seite/AI2 MQTT

TIMAI2 · July 6, 2022, 2:12pm

@Moh_Khafil_A

You have posted the same on Kodular Community. Are you working with Kodular or App Inventor ?

Moh_Khafil_A · July 6, 2022, 2:55pm

sorry I just want to receive input and suggestions from different forums , because the two platforms are almost the same implementation . is this against the rules? thanks