如何使用 Node-RED和Raspberry Pi树莓派MQTT控制ESP32上的LED
在本教程中，您将学习如何使用Node-RED（一种物联网 (IoT) 可视化编程工具）通过 Raspberry Pi树莓派作为MQTT代理来控制ESP32板上的LED。MQTT是一种轻量级且简单的消息传递协议，允许设备通过网络相互通信。该项目将需要以下组件：ESP32开发板用于将ESP32 连接到计算机的USB 电缆带有Node-RED的Raspberry Pi树莓派安装有ArduinoIDE和PubSubClient库的计算机为您的项目制造PCB
步骤 1：在 Qubitro上创建设备
第一步是在 Qubitro平台上创建设备。设备代表云上的物理设备（树莓派Raspberry Pi）。您需要创建一个设备来获取树莓派Raspberry Pi的MQTT凭据和主题。
要在Qubitro上创建设备，请按照以下步骤操作：
1、登录您的Qubitro 帐户并创建一个新项目
2.然后进入“设备”页面，选择“MQTT”作为通信协议，然后单击“下一步”。
3、输入所有详细信息。
4、复制设备 ID、设备令牌、主机名、端口、发布主题和订阅主题。您稍后将在代码中需要这些值。单击“完成”。
您已在Qubitro上成功创建设备。您可以在“设备”页面上看到您的设备。
第 2 步：使用 Arduino IDE 刷新 ESP32
ESP32 是一款功能强大且多功能的微控制器，可以运行 Arduino 代码。您将使用 Arduino IDE 对 ESP32 进行编程，并使其使用 PubSubClient 库与 MQTT 代理进行通信。
要在Arduino IDE中安装ESP32板，您可以按照本教程中的说明操作或使用以下步骤：
从 Arduino IDE 打开首选项窗口：文件 > 首选项。转到“其他板管理器 URL”字段并输入以下 URL： https: //dl.espressif.com/dl/package_esp32_index.json
打 Boards Manager（工具 > Board > Boards Manager），搜索ESP32，然后单击“ESP32 by Espressif Systems”的安装按钮。
安装后，从“工具”>“开发板”菜单中选择您的 ESP32 开发板。
从 Sketch > Include Library > Manage Libraries 打开库管理器。搜索 PubSubClient 并单击“PubSubClient by Nick O'Leary”的安装按钮。安装后重新启动 Arduino IDE。
第3步：将LED连接到ESP32
LED是一种简单的器件，当电流流过时就会发光。您将LED连接到ESP32的GPIO引脚之一，并使用MQTT消息控制其状态（打开或关闭）。
就我而言，我将使用ESP32开发板上的板载LED。
第四步：为ESP32编写代码
ESP32的代码将执行以下任务：
连接到您的Wi-Fi 网络连接到树莓派Raspberry Pi上 Qubitro MQTT代理从“输出”接收消息并相应地打开或关闭LED
您可以将以下代码复制并粘贴到您的Arduino IDE中。确保将 <your_ssid>、<your_password>、<your_Qubtro_Credientials> 替换为您自己的值。
代码：
#include <WiFi.h>
#define DEBUG_SW 1
#include <PubSubClient.h>
//Relays for switching appliances
#define Relay1 2
int switch_ON_Flag1_previous_I = 0;
// Update these with values suitable for your network.
const char* ssid = "ELDRADO";
const char* password = "amazon123";
const char* mqtt_server = "broker.qubitro.com"; // Local IP address of Raspberry Pi
const char* username = "";
const char* pass = "";
// Subscribed Topics
#define sub1 "output"
WiFiClient espClient;
PubSubClient client(espClient);
unsigned long lastMsg = 0;
#define MSG_BUFFER_SIZE(50)
char msg;
int value = 0;
// Connecting to WiFi Router
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("] ");
if (strstr(topic, sub1))
{
for (int i = 0; i < length; i++)
{
Serial.print((char)payload);
}
Serial.println();
// Switch on the LED if an 1 was received as first character
if ((char)payload == 'f')
{
digitalWrite(Relay1, 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(Relay1, HIGH);// Turn the LED off by making the voltage HIGH
}
}
else
{
Serial.println("unsubscribed topic");
}
}
// Connecting to MQTT broker
void reconnect()
{
// Loop until we're reconnected
while (!client.connected()) {
Serial.print("Attempting MQTT connection...");
// Create a random client ID
String clientId = "ESP8266Client-";
clientId += String(random(0xffff), HEX);
// Attempt to connect
if (client.connect(clientId.c_str() , username, pass)) {
Serial.println("connected");
// Once connected, publish an announcement...
client.publish("outTopic", "hello world");
// ... and resubscribe
client.subscribe(sub1);
} 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()
{
pinMode(Relay1, OUTPUT);
Serial.begin(115200);
setup_wifi();
client.setServer(mqtt_server, 1883);
client.setCallback(callback);
}
void loop()
{
if (!client.connected())
{
reconnect();
}
client. Loop();
}
编写代码后，从“工具”菜单中选择正确的板和端口，然后单击“上传”按钮，将其上传到 ESP32 板。
步骤 5：创建 Node-RED 流
Node-RED流程将执行以下任务：
连接到树莓派Raspberry Pi上的MQTT代理订阅名为“output”的主题将消息“true”或“false”发布到名为“output”的主题创建带有按钮和文本节点的仪表板
您可以通过从面板中拖放节点并用电线连接它们来创建 Node-RED流。您还可以从此链接导入流程或使用下面的 JSON 代码：
代码：
{
"id": "eb8f9c0d054be30c",
"type": "tab",
"label": "Flow 2",
"disabled": false,
"info": "",
"env": []
},
{
"id": "4ce6cd876fd5441f",
"type": "mqtt out",
"z": "eb8f9c0d054be30c",
"name": "",
"topic": "output",
"qos": "",
"retain": "",
"respTopic": "",
"contentType": "",
"userProps": "",
"correl": "",
"expiry": "",
"broker": "6d40b7b21c734b53",
"x": 870,
"y": 240,
"wires": []
},
{
"id": "974a7a8bb6db9bf9",
"type": "mqtt in",
"z": "eb8f9c0d054be30c",
"name": "",
"topic": "output",
"qos": "2",
"datatype": "auto-detect",
"broker": "6d40b7b21c734b53",
"nl": false,
"rap": true,
"rh": 0,
"inputs": 0,
"x": 670,
"y": 320,
"wires": [
[
"d0dc7378c7bfb03b",
"f1219a2eeabe825f"
]
]
},
{
"id": "d0dc7378c7bfb03b",
"type": "debug",
"z": "eb8f9c0d054be30c",
"name": "debug 4",
"active": true,
"tosidebar": true,
"console": false,
"tostatus": false,
"complete": "payload",
"targetType": "msg",
"statusVal": "",
"statusType": "auto",
"x": 880,
"y": 320,
"wires": []
},
{
"id": "6bd227b280e372b7",
"type": "ui_switch",
"z": "eb8f9c0d054be30c",
"name": "",
"label": "Light One",
"tooltip": "",
"group": "cd687a95.00e108",
"order": 0,
"width": 0,
"height": 0,
"passthru": true,
"decouple": "false",
"topic": "topic",
"topicType": "msg",
"style": "",
"onvalue": "true",
"onvalueType": "bool",
"onicon": "",
"oncolor": "",
"offvalue": "false",
"offvalueType": "bool",
"officon": "",
"offcolor": "",
"animate": false,
"x": 680,
"y": 240,
"wires": [
[
"4ce6cd876fd5441f"
]
]
},
{
"id": "f1219a2eeabe825f",
"type": "ui_text",
"z": "eb8f9c0d054be30c",
"group": "cd687a95.00e108",
"order": 1,
"width": "6",
"height": "2",
"name": "",
"label": "Status : ",
"format": "{{msg.payload}}",
"layout": "row-center",
"x": 1060,
"y": 320,
"wires": []
},
{
"id": "6d40b7b21c734b53",
"type": "mqtt-broker",
"name": "Qubitro Downlink",
"broker": "broker.qubitro.com",
"port": "1883",
"clientid": "",
"autoConnect": true,
"usetls": false,
"protocolVersion": "4",
"keepalive": "60",
"cleansession": true,
"autoUnsubscribe": true,
"birthTopic": "r43MsJYzcVwZtUXVfZo6XD0Ym7CRegewPQXMt$ho",
"birthQos": "0",
"birthPayload": "",
"birthMsg": {},
"closeTopic": "",
"closeQos": "0",
"closePayload": "",
"closeMsg": {},
"willTopic": "",
"willQos": "0",
"willPayload": "",
"willMsg": {},
"userProps": "",
"sessionExpiry": ""
},
{
"id": "cd687a95.00e108",
"type": "ui_group",
"name": "ESP32 Home Controller",
"tab": "aa146f4d.b53ca",
"order": 1,
"disp": true,
"width": "6",
"collapse": false
},
{
"id": "aa146f4d.b53ca",
"type": "ui_tab",
"name": "Demo Lab",
"icon": "dashboard",
"order": 1,
"disabled": false,
"hidden": false
}
输入开关在打开时将发送“true”，在触发关闭时将发送“false”。
然后单击Qubitro上行链路托盘并编辑属性。
在这里您需要替换您的连接详细信息和凭据。
接下来，只需部署流程即可。并导航到node-red服务器的/ui。
您可以在此处切换开关以打开和关闭导联。
另外，打开串行监视器并检查节点红色响应。
结论：
在本教程中，我们了解了如何使用Node-Red和MQTT服务器控制LED。
本文作者：CETech
原文地址：https://community.dfrobot.com/makelog-313500.html
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