SolderHub Editorial
Articles &
Guides
In-depth tutorials, component deep-dives, and hardware engineering insights — written for builders.
Page 8
NodeMCU ESP8266 MQTT LED Control with Mosquitto
Control a NodeMCU ESP8266 LED by publishing ON/OFF commands to Mosquitto over MQTT. Configure command and reported-state topics, wire an external LED, test with command-line clients and troubleshoot broker access.
ESP32 Relay Control over MQTT with State Feedback
Control relay channels from MQTT with separate command and reported-state topics. Define a safe startup policy, validate commands, handle retained messages carefully and test the relay controller with low-voltage loads.
ESP32 Automatic Plant Watering with Blynk and Soil Moisture Sensor
Build an ESP32 plant-watering system with a soil-moisture sensor and Blynk dashboard. Calibrate wet/dry readings, use hysteresis, limit pump runtime, and keep a safe local policy if Wi-Fi or cloud access disappears.
PIR Motion Notifications with Blynk Events on ESP32
Use an ESP32 PIR input to send Blynk event notifications on a new motion transition. Configure the event, add a cooldown to reduce repeated alerts, and handle sensor warm-up and cloud disconnection.
Blynk Scheduling and Automations for ESP32 Projects
Plan schedules and automations for Blynk-connected ESP32 projects. Separate cloud automation from local time-based logic, handle timezone and connectivity failures, and define safe behavior for relays and pumps.
How to Install Node-RED on Windows: Node.js, First Launch & Troubleshooting
Install Node-RED on Windows using Node.js and npm, launch the editor at localhost:1880, verify your first flow, and fix common PowerShell and startup issues.
Wemos D1 Mini Pinout: Every Pin Explained (GPIO Mapping, Boot Pins, Power)
D1 is GPIO5, not GPIO1 — the full Wemos D1 Mini pin mapping, the D3/D4/D8 boot-mode gotchas, and the voltage rules that actually matter.
TB6612FNG vs L298N Motor Driver: Which One Should You Use?
The L298N drops about 2.5 V at 1 A and runs hot. The TB6612FNG drops about 0.5 V. A datasheet-based comparison of voltage drop, heat, current ratings, 3.3 V logic, wiring and code for Arduino and ESP32, with a clear verdict.
STM32 Nucleo Pinout: Arduino Headers, Morpho Connectors, and GPIO Explained
Complete STM32 Nucleo pinout reference: Arduino-compatible headers vs ST Morpho connectors, the built-in ST-LINK debugger, ADC voltage limits, and every peripheral pin mapped.
ESP32 BLE Scanner: Find Nearby Bluetooth Devices, RSSI & iBeacons
Turn an ESP32 into a Bluetooth Low Energy scanner that lists every nearby device with its RSSI, manufacturer and iBeacon flag — complete Arduino code, the theory behind each line, and an honest look at why RSSI distance is only an estimate.
Raspberry Pi Pico 2 W Pinout: Every GPIO, ADC, and What Changed from Pico W
A complete Raspberry Pi Pico 2 W pinout reference covering GPIO, ADC, PWM, I2C, SPI, and UART -- plus the two things that actually changed from the Pico W: RP2350 analog behavior and a relocated debug header.
MAX30102 Heart Rate & SpO2 Sensor with ESP32 and Arduino Uno
Wire the MAX30102 pulse oximeter to an ESP32 or Arduino Uno, detect heartbeats, read SpO2, plot the raw PPG waveform, and understand why the readings wobble. Four tested-logic sketches included.