ESP32 and Arduino tutorials: sensors, MQTT, TLS, deep sleep and OTA, with examples connected to the public broker broker.connectmq.com.
Sync the ESP32 clock with NTP, format ISO 8601 and epoch-millisecond timestamps, and attach them to MQTT payloads so readings keep their true capture time even when they are published late.
Build an ESP-IDF project from an empty folder with the esp-mqtt component: Wi-Fi station setup, the MQTT event handler, publish and subscribe, MQTT 5 properties and TLS with the certificate bundle.
A hands-on ESP-IDF project that enables MQTT 5.0 in esp-mqtt and uses user properties, message expiry, topic aliases, session expiry and response topics against a real MQTT 5 broker.
Go from an unboxed ESP32 to a secure, cloud-connected temperature sensor: Arduino IDE setup, Wi-Fi, a DHT22, MQTT publish and subscribe, remote LED control and TLS on port 8883.
A practical PubSubClient tutorial for ESP32 and ESP8266: install the library, connect to an MQTT broker, handle callbacks, size the buffer, tune keep alive and move to TLS with real credentials.
Structure an ESP32 PlatformIO MQTT project with separate dev and production environments, broker settings injected at build time, secrets kept out of version control and pinned library versions.
Turn an ESP32 and a 3.3 V RS485 transceiver into a small Modbus RTU master that polls meters and sensors, scales register values and publishes them as JSON over MQTT.
Connect an ESP32 running MicroPython to an MQTT broker with umqtt.simple, add automatic reconnects with umqtt.robust, receive commands without blocking and understand what these minimal clients cannot do.
Use a W5500 SPI module or a LAN8720 PHY to put an ESP32 on wired Ethernet, handle cable and link events cleanly, and publish machine data over MQTT without depending on Wi-Fi.
Split sensor sampling and MQTT publishing into two FreeRTOS tasks on the ESP32, connect them with a queue and keep readings flowing even while Wi-Fi or the broker reconnects.
Clamp an SCT-013 current transformer on a mains cable, measure RMS current with the ESP32 ADC, estimate power and energy, and publish the results to broker.connectmq.com for energy dashboards.
A practical design guide for an ESP32 battery powered sensor: board choice, low-quiescent regulators, battery voltage monitoring, fast Wi-Fi reconnects and MQTT publish intervals that stretch battery life.
Connect the Arduino UNO R4 WiFi to an MQTT broker with WiFiS3 and ArduinoMqttClient, publish analog readings, control the LED matrix from your laptop and move to TLS on port 8883.
Connect an ESP32 to an MQTT broker over TLS on port 8883 with WiFiClientSecure and PubSubClient, verify the server with the right root CA, sync time and keep heap usage under control.
Stop hard-coding credentials: let users enter Wi-Fi plus MQTT host, port, client ID, username and password in a WiFiManager captive portal, store them with Preferences and connect to broker.connectmq.com by default.
Replace the blocking reconnect loop from most examples with a non-blocking state machine for Wi-Fi and MQTT, with exponential backoff, jitter, resubscribe and an offline buffer, then prove it by rebooting your router.
Trigger ESP32 firmware updates with an MQTT command, download the binary over HTTPS with HTTPUpdate, and publish progress and results to a retained status topic so you always know which version each device runs.
Wire several DS18B20 probes to a single ESP32 GPIO, discover their ROM addresses, read them without blocking and publish each probe to its own topic on broker.connectmq.com.
Move a servo from MQTT commands with an ESP32 and the ESP32Servo library, ramp it smoothly to the target angle and publish position feedback that dashboards can display.
Read a NEO-6M GPS module with the ESP32, publish position, speed and fix quality over MQTT only when the device moves, and display the track live on a Leaflet map over secure WebSocket.
A practical comparison of the ESP32 and Raspberry Pi Pico W for connected projects, covering hardware, Wi-Fi and Bluetooth, programming options, TLS performance, low-power modes and MQTT code on both.
Use an ESP32 as a Bluetooth Low Energy scanner that collects advertisements from nearby sensors and beacons, filters and deduplicates them, and publishes them to per-device MQTT topics.
Choosing between the ESP32 and ESP8266 for an MQTT device? This comparison covers memory, TLS capability, peripherals, power, library support and cost, with clear recommendations by project type.
Wire a relay module to an ESP32, switch it from an MQTT command topic and publish retained state so every dashboard and app always knows whether the load is on or off.
PubSubClient prints "failed, rc=-2" and nothing else? This guide decodes every state code from -4 to 5 and gives tested fixes for DNS, port, TLS, client ID and credential problems.
Drive a NEMA 17 stepper from MQTT position commands with an ESP32, AccelStepper and an A4988 or DRV8825 driver, and publish live progress so apps know where the motor is.
Serialize sensor readings and parse incoming JSON commands with ArduinoJson 7 on an ESP32, publish them over MQTT with PubSubClient, and avoid the buffer and memory pitfalls that silently drop messages.
Learn how AsyncMqttClient keeps ESP32 firmware responsive: event-driven callbacks, automatic reconnects with FreeRTOS timers, QoS 1 and 2 publishing and fragmented payload handling.
Read temperature, humidity and pressure from a BME280 over I2C, publish JSON to broker.connectmq.com, and change the publish interval at runtime with a retained MQTT command stored in flash.
Large MQTT messages failing silently on your ESP32 or ESP8266? Learn how the PubSubClient buffer works, how to size it with setBufferSize, and how to stream big JSON payloads without wasting RAM.
Create an account, get your broker credentials and connect your first device — no servers to install, patch or scale.
