shelly 1 temperature sensor

• time：2025-08-25 03:21:17
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Transform Your Shelly 1 into a DIY Temperature Monitoring Powerhouse

Imagine controlling your lights, appliances, or garage door remotely with the versatile Shelly 1 smart switch. It’s a fantastic piece of hardware, offering cloud and local control to automate your home. But what if you could unlock an entirely new capability hidden within its compact form? What if this affordable device could also become your vigilant temperature sensor, alerting you to potential freezer failures, overheating server cabinets, or even fluctuating room conditions? The exciting reality is that with a simple, inexpensive modification, your Shelly 1 can become a powerful Shelly 1 temperature monitoring tool.

The Shelly 1 itself isn’t natively equipped with an integrated temperature sensor. Its core function is to act as a robust relay switch, intelligently turning connected devices on or off based on schedules, app commands, web interfaces, or integrations with platforms like Home Assistant, Google Home, or Alexa. However, Shelly’s engineers included a powerful feature often overlooked: an Analog-to-Digital Converter (ADC) input accessible via the GPIO34 header pin on the device. This input is designed to measure voltage levels (typically 0-3.3V or 0-10V depending on configuration). This is the critical gateway we exploit to add temperature sensing.

This transformation hinges on a fundamental electronic component: an NTC (Negative Temperature Coefficient) thermistor. This small, inexpensive sensor changes its electrical resistance predictably in response to changes in temperature – as the temperature increases, its resistance decreases. To interface this thermistor with the Shelly 1’s ADC, we create a simple voltage divider circuit. Here’s the setup:

1. Connect one leg of the NTC thermistor (usually 10kΩ at 25°C is a common, compatible value) to the +3.3V power pin (often labeled 3V3 or VCC) on the Shelly 1’s header.
2. Connect the other leg of the NTC thermistor to the ADC input pin (GPIO34).
3. Connect a fixed resistor (commonly 10kΩ, matching the thermistor’s nominal value) between the ADC input pin (GPIO34) and the Ground (GND) pin.

In this configuration, the NTC thermistor and the fixed resistor form the voltage divider. The Shelly 1 measures the voltage at the junction point (GPIO34). As the temperature changes, the resistance of the NTC changes, altering this voltage. The Shelly firmware then converts this measured voltage into a resistance value using the known value of the fixed resistor, and subsequently converts that resistance into a temperature reading using the thermistor’s specified beta (β) coefficient or lookup table.

Transforming your Shelly 1 into a functional temperature sensor is remarkably straightforward. Here’s what you’ll need and the basic process:

• Materials Needed: Your Shelly 1 smart switch; A compatible NTC thermistor (e.g., 10kΩ, β=3950); A fixed resistor (e.g., 10kΩ); Thin hookup wire; Soldering iron & solder (or suitable connectors like JST or Dupont if using compatible pre-wired sensors); Basic tools (wire strippers, etc.).
• Safety First: Always disconnect mains power before opening the Shelly 1’s case or working on its internal header.
• Access the Headers: Carefully open the Shelly 1 case to reveal the internal PCB and the header pins (3V3, GND, GPIO34, etc.).
• Solder the Circuit: Solder wires to the legs of your NTC thermistor and the fixed resistor. Connect them according to the voltage divider schematic described above:
• Attach one thermistor wire to 3V3.
• Attach the junction wire (connecting the thermistor’s other leg AND one leg of the fixed resistor) to GPIO34.
• Attach the remaining leg of the fixed resistor to GND.
• Position the Sensor: Carefully route the thermistor wires out of the Shelly 1 enclosure. You can seal the exit point with hot glue or silicone for strain relief and insulation. Mount the thermistor probe where you need temperature monitoring (e.g., inside a fridge, near electronics, in a room corner). Ensure the thermistor wires cannot touch mains voltage terminals inside the Shelly 1 – this is crucial to prevent shorts or a fire hazard.
• Configure in the App:
• Power the Shelly 1 back up and connect to its Wi-Fi.
• Open the Shelly Smart Control app (or web interface).
• Navigate to your Shelly 1 device settings.
• Go to ADC (or Analog Input) settings.
• Set the ADC Type to Temperature. (This is vital!)
• Configure specific parameters: Set R1 to the value of your fixed resistor (e.g., 10000 Ω). Set β (Beta) to the value specified for your NTC thermistor (e.g., 3950). You might need to adjust the offset if readings seem slightly off after calibration. Save the settings.

Accuracy is paramount for reliable monitoring, so calibration is highly recommended. While the Beta value provides a theoretical curve, actual components can have slight variances. Compare your Shelly 1’s initial readings against a known accurate reference thermometer placed near your thermistor probe at a stable temperature (like room temperature water in an insulated container). If there’s a consistent offset, apply that adjustment value in the Shelly device’s “Offset” field within the ADC/Temperature settings. This simple step significantly enhances the reliability of your DIY sensor.

Unlocking temperature sensing transforms your humble Shelly 1 into a versatile guardian across numerous scenarios:

• Appliance & Equipment Health: Monitor your refrigerator or freezer temperature remotely. Receive instant alerts via the Shelly app if temperatures rise dangerously, potentially saving hundreds in spoiled food. Prevent costly damage by monitoring a server cabinet, network closet, or entertainment center for overheating.
• Environmental Comfort & Efficiency: Track temperatures in specific rooms, attics, garages, or greenhouses. Use this data in automations – e.g., triggering a fan when the attic exceeds a threshold, or activating ventilation in a greenhouse. *