ESP32 自託管 IoT 平台教學：15 分鐘發送第一條 MQTT 訊息

This article is cross-posted from the ThingBoot Guides repository on GitHub, where you'll also find the Chinese version.

Most ESP32 tutorials stop at "blink an LED". Real products need the next step:
get your device talking to a platform you own — not someone else's cloud.

This guide walks you from a stock ESP32 to publishing telemetry and receiving
commands over MQTT against a self-hosted broker. It takes about 15 minutes.

What you need

• An ESP32 dev board (ESP32 / ESP32-S3 / ESP32-C3 all work)
• USB cable + Arduino IDE (or PlatformIO)
• A machine that can run an MQTT broker (Docker is fine)

Architecture

[ESP32] --WiFi--> [MQTT Broker (self-hosted)] ---> [Your apps / dashboards / AI agents]
         <-------- (commands, OTA triggers) ------

Self-hosting the broker means: your data stays on your network, you control
auth, and AI agents can talk to devices through the same topics later.

Step 1 — Run a broker

The fastest way to get a local broker:

docker run -d -p 1883:1883 --name mosquitto eclipse-mosquitto

Then create a minimal mosquitto.conf allowing local testing:

listener 1883
allow_anonymous true

For production: always enable auth + TLS. See the OTA & safe-mode guide.

Step 2 — Flash the ESP32

Install the ThingBoot ESP Arduino SDK,
which wraps WiFi provisioning, MQTT reconnect, and OTA into a setup()/loop()
model. Or use plain Arduino with PubSubClient — the flow is the same:

#include <WiFi.h>
#include <PubSubClient.h>

WiFiClient net;
PubSubClient mqtt(net);

void setup() {
  Serial.begin(115200);
  WiFi.begin("YOUR_SSID", "YOUR_PASSWORD");
  while (WiFi.status() != WL_CONNECTED) delay(500);

  mqtt.setServer("192.168.1.100", 1883);   // your broker's LAN IP
  mqtt.setCallback([](char* topic, byte* payload, unsigned int len) {
    Serial.printf("command received on %s: %.*s\n", topic, len, (char*)payload);
  });
}

void loop() {
  if (!mqtt.connected()) mqtt.connect("esp32-demo");
  mqtt.loop();

  static uint32_t last = 0;
  if (millis() - last > 5000) {
    last = millis();
    mqtt.publish("things/esp32-demo/telemetry",
                 "{\"temp\":25.5,\"rssi\":-60}");
  }
}

Step 3 — Verify

Subscribe from your computer and watch data arrive:

mosquitto_sub -h 192.168.1.100 -t "things/#" -v

Then send a command back to the device:

mosquitto_pub -h 192.168.1.100 -t "things/esp32-demo/cmd" -m '{"relay":"on"}'

If you see telemetry flowing and the device reacting to commands — congratulations,
that's the entire foundation of an IoT fleet: device → platform → device.

Where to go next

ThingBoot provides free device SDKs and a self-hosted IoT platform.
Questions? Open an issue.