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Learn Tai Chi Maker - mqtt (VIII) esp8266 subscribe to mqtt topic
2022-06-27 02:14:00 【xuechanba】
The data link ：http://www.taichi-maker.com/homepage/esp8266-nodemcu-iot/iot-tuttorial/mqtt-tutorial/esp8266-subscribe-mqtt/
1、 Subscribe to a single topic
/********************************************************************** Project name /Project : Zero basic introduction to the Internet of things Program name /Program name : subscribe_ranye_url The team /Team : Taiji maker team / Taichi-Maker (www.taichi-maker.com) author /Author : CYNO Shuo date /Date（YYYYMMDD） : 20200708 Purpose of procedure /Purpose : The purpose of this program is to demonstrate how to use PubSubClient Library usage ESP8266 towards MQTT Server subscription information . ----------------------------------------------------------------------- This sample program is made by Taiji maker team 《 Zero basic introduction to the Internet of things 》 Sample program in . This tutorial is designed and produced by friends who are interested in the development of the Internet of things . For more information about this tutorial , Please refer to the following pages ： http://www.taichi-maker.com/homepage/esp8266-nodemcu-iot/iot-c/esp8266-nodemcu-web-client/http-request/ ***********************************************************************/
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
// Set up wifi Access information ( Please according to your WiFi Modify the information )
const char* ssid = "FAST_153C80";
const char* password = "123456798";
const char* mqttServer = "test.ranye-iot.net";
// As above MQTT The server cannot connect normally , Please go to the following page to find a solution
// http://www.taichi-maker.com/public-mqtt-broker/
WiFiClient wifiClient;
PubSubClient mqttClient(wifiClient);
void setup() {
pinMode(LED_BUILTIN, OUTPUT); // Set up on the board LED Pin is output mode
digitalWrite(LED_BUILTIN, HIGH); // Turn it on and off the board LED
Serial.begin(9600); // Start serial communication
// Set up ESP8266 The working mode is wireless terminal mode
WiFi.mode(WIFI_STA);
// Connect WiFi
connectWifi();
// Set up MQTT Server and port number
mqttClient.setServer(mqttServer, 1883);
// Set up MQTT Subscription callback function
mqttClient.setCallback(receiveCallback);
// Connect MQTT The server
connectMQTTserver();
}
void loop() {
if (mqttClient.connected()) {
// If the development board successfully connects to the server
mqttClient.loop(); // Process information and heartbeat
} else {
// If the development board fails to connect to the server
connectMQTTserver(); // Then try to connect to the server
}
}
// Connect MQTT Server and subscribe to information
void connectMQTTserver(){
// according to ESP8266 Of MAC Address generation client ID（ Avoid contact with other ESP8266 The client of ID The nuptial ）
String clientId = "esp8266-" + WiFi.macAddress();
// Connect MQTT The server
if (mqttClient.connect(clientId.c_str())) {
Serial.println("MQTT Server Connected.");
Serial.println("Server Address:");
Serial.println(mqttServer);
Serial.println("ClientId: ");
Serial.println(clientId);
subscribeTopic(); // Subscribe to specific topics
} else {
Serial.print("MQTT Server Connect Failed. Client State:");
Serial.println(mqttClient.state());
delay(5000);
}
}
// Callback function after receiving information
void receiveCallback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message Received [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}
Serial.println("");
Serial.print("Message Length(Bytes) ");
Serial.println(length);
if ((char)payload[0] == '1') {
// If you receive a message with “1” For the beginning
digitalWrite(BUILTIN_LED, LOW); // Then light up LED.
Serial.println("LED ON");
} else {
digitalWrite(BUILTIN_LED, HIGH); // Otherwise, it goes out LED.
Serial.println("LED OFF");
}
}
// Subscribe to specific topics
void subscribeTopic(){
// Create a subscription topic . The title of the topic is Taichi-Maker-Sub The prefix , The device is added later MAC Address .
// This is to make sure that different devices use the same MQTT When the server tests the message subscription , The topic names you subscribe to are different
String topicString = "Taichi-Maker-Sub-" + WiFi.macAddress();
char subTopic[topicString.length() + 1];
strcpy(subTopic, topicString.c_str());
// The serial port monitor outputs whether the topic is successfully subscribed and the name of the subscription topic
if(mqttClient.subscribe(subTopic)){
Serial.println("Subscrib Topic:");
Serial.println(subTopic);
} else {
Serial.print("Subscribe Fail...");
}
}
// ESP8266 Connect wifi
void connectWifi(){
WiFi.begin(ssid, password);
// wait for WiFi Connect , Output success information after successful connection
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi Connected!");
Serial.println("");
}
The program runs as follows ,
Let's try again MQTT.fx This software provides Taichi-Maker-Sub-EC:FA:BC:40:6F:5B This topic publishes information , At the same time, observe the output of the serial port monitor .
When LED ON when ,ESP8266 On board LED Also lit .
below , To explain the key points of the program .
// Set up MQTT Subscription callback function
mqttClient.setCallback(receiveCallback);
Here ESP8266 The function of the development board is to subscribe MQTT The theme , It is subscribing MQTT After the theme , Whenever you receive this topic message , He will call a callback function receiveCallback , To process the received information .
2、 Subscribe to specific topics
// The serial port monitor outputs whether the topic is successfully subscribed and the name of the subscription topic
if(mqttClient.subscribe(subTopic)){
Serial.println("Subscrib Topic:");
Serial.println(subTopic);
} else {
Serial.print("Subscribe Fail...");
}
mqttClient.subscribe(subTopic) Will try to subscribe to a topic , The theme is called “Taichi-Maker-Sub-” + WiFi.macAddress(),
If the subscription is successful, it will return 1 .
3、 Callback function after receiving information
void receiveCallback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message Received [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}
Serial.println("");
Serial.print("Message Length(Bytes) ");
Serial.println(length);
if ((char)payload[0] == '1') {
// If you receive a message with “1” For the beginning
digitalWrite(BUILTIN_LED, LOW); // Then light up LED.
Serial.println("LED ON");
} else {
digitalWrite(BUILTIN_LED, HIGH); // Otherwise, it goes out LED.
Serial.println("LED OFF");
}
}
Notice the three parameters , The three parameters are fixed format .
topic It's the theme name
payload Is the content of specific information , It's an array type
length Is the length of the specific information
2、 Subscribe to multiple topics
/********************************************************************** Project name /Project : Zero basic introduction to the Internet of things Program name /Program name : subscribe_multitopic_ranye_url The team /Team : Taiji maker team / Taichi-Maker (www.taichi-maker.com) author /Author : CYNO Shuo date /Date（YYYYMMDD） : 20201125 Purpose of procedure /Purpose : The purpose of this program is to demonstrate how to use PubSubClient Library usage ESP8266 towards MQTT The server subscribes to multiple topics ----------------------------------------------------------------------- This sample program is made by Taiji maker team 《 Zero basic introduction to the Internet of things 》 Sample program in . This tutorial is designed and produced by friends who are interested in the development of the Internet of things . For more information about this tutorial , Please refer to the following pages ： http://www.taichi-maker.com/homepage/esp8266-nodemcu-iot/iot-c/esp8266-nodemcu-web-client/http-request/ ***********************************************************************/
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
// Set up wifi Access information ( Please according to your WiFi Modify the information )
const char* ssid = "FAST_153C80";
const char* password = "123456798";
const char* mqttServer = "test.ranye-iot.net";
// As above MQTT The server cannot connect normally , Please go to the following page to find a solution
// http://www.taichi-maker.com/public-mqtt-broker/
WiFiClient wifiClient;
PubSubClient mqttClient(wifiClient);
void setup() {
pinMode(LED_BUILTIN, OUTPUT); // Set up on the board LED Pin is output mode
digitalWrite(LED_BUILTIN, HIGH); // Turn it on and off the board LED
Serial.begin(9600); // Start serial communication
// Set up ESP8266 The working mode is wireless terminal mode
WiFi.mode(WIFI_STA);
// Connect WiFi
connectWifi();
// Set up MQTT Server and port number
mqttClient.setServer(mqttServer, 1883);
mqttClient.setCallback(receiveCallback);
// Connect MQTT The server
connectMQTTserver();
}
void loop() {
if (mqttClient.connected()) {
// If the development board successfully connects to the server
mqttClient.loop(); // Process information and heartbeat
} else {
// If the development board fails to connect to the server
connectMQTTserver(); // Then try to connect to the server
}
}
// Connect MQTT Server and subscribe to information
void connectMQTTserver(){
// according to ESP8266 Of MAC Address generation client ID（ Avoid contact with other ESP8266 The client of ID The nuptial ）
String clientId = "esp8266-" + WiFi.macAddress();
// Connect MQTT The server
if (mqttClient.connect(clientId.c_str())) {
Serial.println("MQTT Server Connected.");
Serial.println("Server Address:");
Serial.println(mqttServer);
Serial.println("ClientId: ");
Serial.println(clientId);
subscribeTopic(); // Subscribe to specific topics
} else {
Serial.print("MQTT Server Connect Failed. Client State:");
Serial.println(mqttClient.state());
delay(5000);
}
}
// Callback function after receiving information
void receiveCallback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message Received [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}
Serial.println("");
Serial.print("Message Length(Bytes) ");
Serial.println(length);
if ((char)payload[0] == '1') {
// If you receive a message with “1” For the beginning
digitalWrite(BUILTIN_LED, LOW); // Then light up LED.
} else {
digitalWrite(BUILTIN_LED, HIGH); // Otherwise, it goes out LED.
}
}
// Subscribe to specific topics
void subscribeTopic(){
// Create a subscription topic 1. The title of the topic is Taichi-Maker-Sub The prefix , The device is added later MAC Address .
// This is to make sure that different devices use the same MQTT When the server tests the message subscription , The topic names you subscribe to are different
String topicString = "Taichi-Maker-Sub-" + WiFi.macAddress();
char subTopic[topicString.length() + 1];
strcpy(subTopic, topicString.c_str());
// Create a subscription topic 2
String topicString2 = "Taichi-Maker-Sub2-" + WiFi.macAddress();
char subTopic2[topicString2.length() + 1];
strcpy(subTopic2, topicString2.c_str());
// Output whether the topic has been successfully subscribed through the serial port monitor 1 And the topics you subscribe to 1 name
if(mqttClient.subscribe(subTopic)){
Serial.println("Subscrib Topic:");
Serial.println(subTopic);
} else {
Serial.print("Subscribe Fail...");
}
// Output whether the topic has been successfully subscribed through the serial port monitor 2 And the topics you subscribe to 2 name
if(mqttClient.subscribe(subTopic2)){
Serial.println("Subscrib Topic:");
Serial.println(subTopic2);
} else {
Serial.print("Subscribe Fail...");
}
}
// ESP8266 Connect wifi
void connectWifi(){
WiFi.begin(ssid, password);
// wait for WiFi Connect , Output success information after successful connection
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi Connected!");
Serial.println("");
}
The running code is as follows ,
Let's try again MQTT.fx This software is directed to Taichi-Maker-Sub-EC:FA:BC:40:6F:5B and Taichi-Maker-Sub2-EC:FA:BC:40:6F:5B These two topics publish information , At the same time, observe the output of the serial port monitor .
No matter which topic you post on , As long as the first character of the message is 1 , Then light up the onboard LED .
3、 Subscribe to topics using single level wildcards
/********************************************************************** Project name /Project : Zero basic introduction to the Internet of things Program name /Program name : subscribe_single_level_wildcard_ranye The team /Team : Taiji maker team / Taichi-Maker (www.taichi-maker.com) author /Author : CYNO Shuo date /Date（YYYYMMDD） : 20200813 Purpose of procedure /Purpose : The purpose of this procedure is to demonstrate ESP8266 Unipolar wildcard when subscribing to information + application . ----------------------------------------------------------------------- This sample program is made by Taiji maker team 《 Zero basic introduction to the Internet of things 》 Sample program in . This tutorial is designed and produced by friends who are interested in the development of the Internet of things . For more information about this tutorial , Please refer to the following pages ： http://www.taichi-maker.com/homepage/esp8266-nodemcu-iot/iot-c/esp8266-nodemcu-web-client/http-request/ ***********************************************************************/
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
// Set up wifi Access information ( Please according to your WiFi Modify the information )
const char* ssid = "taichi-maker";
const char* password = "12345678";
const char* mqttServer = "test.ranye-iot.net";
// As above MQTT The server cannot connect normally , Please go to the following page to find a solution
// http://www.taichi-maker.com/public-mqtt-broker/
WiFiClient wifiClient;
PubSubClient mqttClient(wifiClient);
void setup() {
pinMode(LED_BUILTIN, OUTPUT); // Set up on the board LED Pin is output mode
digitalWrite(LED_BUILTIN, HIGH); // Turn it on and off the board LED
Serial.begin(9600); // Start serial communication
// Set up ESP8266 The working mode is wireless terminal mode
WiFi.mode(WIFI_STA);
// Connect WiFi
connectWifi();
// Set up MQTT Server and port number
mqttClient.setServer(mqttServer, 1883);
mqttClient.setCallback(receiveCallback);
// Connect MQTT The server
connectMQTTserver();
}
void loop() {
if (mqttClient.connected()) {
// If the development board successfully connects to the server
mqttClient.loop(); // Process information and heartbeat
} else {
// If the development board fails to connect to the server
connectMQTTserver(); // Then try to connect to the server
}
}
// Connect MQTT Server and subscribe to information
void connectMQTTserver(){
// according to ESP8266 Of MAC Address generation client ID（ Avoid contact with other ESP8266 The client of ID The nuptial ）
String clientId = "esp8266-" + WiFi.macAddress();
// Connect MQTT The server
if (mqttClient.connect(clientId.c_str())) {
Serial.println("MQTT Server Connected.");
Serial.println("Server Address:");
Serial.println(mqttServer);
Serial.println("ClientId: ");
Serial.println(clientId);
subscribeTopic(); // Subscribe to specific topics
} else {
Serial.print("MQTT Server Connect Failed. Client State:");
Serial.println(mqttClient.state());
delay(5000);
}
}
// Callback function after receiving information
void receiveCallback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message Received [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}
Serial.println("");
Serial.print("Message Length(Bytes) ");
Serial.println(length);
if ((char)payload[0] == '1') {
// If you receive a message with “1” For the beginning
digitalWrite(BUILTIN_LED, LOW); // Then light up LED.
} else {
digitalWrite(BUILTIN_LED, HIGH); // Otherwise, it goes out LED.
}
}
// Subscribe to specific topics
void subscribeTopic(){
// Create a subscription topic . The title of the topic is Taichi-Maker-Sub The prefix , The device is added later MAC Address .
// This is to make sure that different devices use the same MQTT When the server tests the message subscription , The topic names you subscribe to are different
String topicString = "Taichi-Maker-Sub-" + WiFi.macAddress()+"/+/data";
char subTopic[topicString.length() + 1];
strcpy(subTopic, topicString.c_str());
// The serial port monitor outputs whether the topic is successfully subscribed and the name of the subscription topic
if(mqttClient.subscribe(subTopic)){
Serial.println("Subscrib Topic:");
Serial.println(subTopic);
} else {
Serial.print("Subscribe Fail...");
}
}
// ESP8266 Connect wifi
void connectWifi(){
WiFi.begin(ssid, password);
// wait for WiFi Connect , Output success information after successful connection
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi Connected!");
Serial.println("");
}
It is similar to the first program .
4、 Use multi-level wildcards to subscribe to topics
/********************************************************************** Project name /Project : Zero basic introduction to the Internet of things Program name /Program name : subscribe_multi_level_wildcard_ranye The team /Team : Taiji maker team / Taichi-Maker (www.taichi-maker.com) author /Author : CYNO Shuo date /Date（YYYYMMDD） : 20200813 Purpose of procedure /Purpose : The purpose of this procedure is to demonstrate ESP8266 Multipole wildcard when subscribing to information # application . ----------------------------------------------------------------------- This sample program is made by Taiji maker team 《 Zero basic introduction to the Internet of things 》 Sample program in . This tutorial is designed and produced by friends who are interested in the development of the Internet of things . For more information about this tutorial , Please refer to the following pages ： http://www.taichi-maker.com/homepage/esp8266-nodemcu-iot/iot-c/esp8266-nodemcu-web-client/http-request/ ***********************************************************************/
#include <ESP8266WiFi.h>
#include <PubSubClient.h>
// Set up wifi Access information ( Please according to your WiFi Modify the information )
const char* ssid = "taichi-maker";
const char* password = "12345678";
const char* mqttServer = "test.ranye-iot.net";
// As above MQTT The server cannot connect normally , Please go to the following page to find a solution
// http://www.taichi-maker.com/public-mqtt-broker/
WiFiClient wifiClient;
PubSubClient mqttClient(wifiClient);
void setup() {
pinMode(LED_BUILTIN, OUTPUT); // Set up on the board LED Pin is output mode
digitalWrite(LED_BUILTIN, HIGH); // Turn it on and off the board LED
Serial.begin(9600); // Start serial communication
// Set up ESP8266 The working mode is wireless terminal mode
WiFi.mode(WIFI_STA);
// Connect WiFi
connectWifi();
// Set up MQTT Server and port number
mqttClient.setServer(mqttServer, 1883);
mqttClient.setCallback(receiveCallback);
// Connect MQTT The server
connectMQTTserver();
}
void loop() {
if (mqttClient.connected()) {
// If the development board successfully connects to the server
mqttClient.loop(); // Process information and heartbeat
} else {
// If the development board fails to connect to the server
connectMQTTserver(); // Then try to connect to the server
}
}
// Connect MQTT Server and subscribe to information
void connectMQTTserver(){
// according to ESP8266 Of MAC Address generation client ID（ Avoid contact with other ESP8266 The client of ID The nuptial ）
String clientId = "esp8266-" + WiFi.macAddress();
// Connect MQTT The server
if (mqttClient.connect(clientId.c_str())) {
Serial.println("MQTT Server Connected.");
Serial.println("Server Address:");
Serial.println(mqttServer);
Serial.println("ClientId: ");
Serial.println(clientId);
subscribeTopic(); // Subscribe to specific topics
} else {
Serial.print("MQTT Server Connect Failed. Client State:");
Serial.println(mqttClient.state());
delay(5000);
}
}
// Callback function after receiving information
void receiveCallback(char* topic, byte* payload, unsigned int length) {
Serial.print("Message Received [");
Serial.print(topic);
Serial.print("] ");
for (int i = 0; i < length; i++) {
Serial.print((char)payload[i]);
}
Serial.println("");
Serial.print("Message Length(Bytes) ");
Serial.println(length);
if ((char)payload[0] == '1') {
// If you receive a message with “1” For the beginning
digitalWrite(BUILTIN_LED, LOW); // Then light up LED.
} else {
digitalWrite(BUILTIN_LED, HIGH); // Otherwise, it goes out LED.
}
}
// Subscribe to specific topics
void subscribeTopic(){
// Create a subscription topic . The title of the topic is Taichi-Maker-Sub The prefix , The device is added later MAC Address .
// This is to make sure that different devices use the same MQTT When the server tests the message subscription , The topic names you subscribe to are different
String topicString = "Taichi-Maker-Sub-" + WiFi.macAddress()+"/sensor/#";
char subTopic[topicString.length() + 1];
strcpy(subTopic, topicString.c_str());
// The serial port monitor outputs whether the topic is successfully subscribed and the name of the subscription topic
if(mqttClient.subscribe(subTopic)){
Serial.println("Subscrib Topic:");
Serial.println(subTopic);
} else {
Serial.print("Subscribe Fail...");
}
}
// ESP8266 Connect wifi
void connectWifi(){
WiFi.begin(ssid, password);
// wait for WiFi Connect , Output success information after successful connection
while (WiFi.status() != WL_CONNECTED) {
delay(1000);
Serial.print(".");
}
Serial.println("");
Serial.println("WiFi Connected!");
Serial.println("");
}
It is similar to the first program .
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