The Shelly Pill: A Tiny USB-C Sensor Bridge That Punches Well Above Its Weight

Got sensors? The Shelly Pill turns basic temperature probes and environmental sensors into smart, connected data, all from a device smaller than a thumb drive.

If you've ever wanted to monitor the temperature in your fish tank, track humidity in a greenhouse, or keep tabs on a server rack but found most smart home sensors either too bulky, too expensive, or too locked into one ecosystem then Shelly's latest product is worth your attention.

The Shelly Pill is a compact WiFi and Bluetooth sensor bridge, powered by USB-C, that takes standard off-the-shelf sensors and makes them smart. No proprietary hub required. No subscription. No cloud dependency if you don't want it. Just plug it in, connect your sensors, and start getting real-time data on your phone or automation platform.

At roughly 26 x 20 x 8.5mm and weighing just 3 grams, it's genuinely tiny. You can tuck it behind a panel, inside an enclosure, next to a server rack, or anywhere else where space is tight and you need reliable environmental data.

What Does It Actually Do?

At its core, the Pill is a bridge between the physical world and your smart home. It reads data from external sensors and makes that data available over WiFi to the Shelly app, to Home Assistant, to any platform that speaks MQTT, HTTP, or WebSocket.

Out of the box, it offers plug-and-play support for two of the most widely used sensor types in the DIY and professional monitoring world.

• DS18B20 digital temperature probes connect via a simple 3.5mm jack, the same type of connector you'd find on a pair of headphones. These are waterproof probes that work brilliantly for monitoring liquids, air temperature, and anything else where you need a reliable, accurate reading.
• DHT22 combined temperature and humidity sensors are also supported, which opens up indoor climate monitoring, greenhouse management, and environmental tracking.

The Pill supports up to five DS18B20 temperature sensors simultaneously from a single device. That's five independent temperature readings, all feeding back to one tiny bridge. We'll come back to how that works in a moment.

Beyond the plug-and-play sensor support, the Pill also offers three configurable digital inputs or outputs at 3.3V logic level, meaning you can connect simple digital sensors like reed switches, motion detectors, or water-level sensors. For more advanced use cases, optional add-on modules extend the Pill's capabilities to include analog voltage measurement up to 30V (useful for monitoring battery systems) and dual-channel solid-state relay control for switching small DC loads like fans, LED indicators, or solenoid valves.

Why This Matters for Your Smart Home

Here's where the Pill gets interesting from a smart home perspective, and why we've added it to the DigIoT catalogue.

It runs on open standards.

The Pill uses WiFi for connectivity and supports MQTT, HTTP, and WebSocket protocols. That means it works with virtually any smart home platform sych asHome Assistant, Node-RED, Homey, or your own custom setup. You're not locked into the Shelly ecosystem, even though the Shelly app is perfectly good if that's what you prefer.

It supports local control.

Built on Shelly's Gen3 platform, the Pill can run local actions, scripts, and automations without needing an internet connection. Your sensor data stays on your network if you want it to. No cloud required. If your broadband goes down, your monitoring keeps working.

It doubles as a Bluetooth gateway.

The Pill includes Bluetooth Low Energy 4.2, and it can act as a gateway for Shelly's BLU series of Bluetooth sensors and devices. If you've already got Shelly BLU door/window sensors or buttons, the Pill extends their range by bridging Bluetooth to WiFi.

It's expandable.

The optional add-on modules analog voltage measurement, solid-state relay switching, and a 5-terminal I/O interface mean the Pill can grow with your needs. Start with a temperature probe, and later add voltage monitoring for a battery system or relay control for a ventilation fan.

Now Add the 1-to-5 Splitter

This is where things get properly useful.

The Shelly 1-to-5 Splitter is a simple accessory cable that takes the Pill's single 3.5mm sensor port and splits it into five 3.5mm sockets. Each socket accepts a DS18B20 temperature probe, giving you five independent measurement points from one Pill.

The splitter uses 21cm cable segments, which gives you enough flexibility to position probes in different spots without everything being jammed together. And because the DS18B20 protocol identifies each sensor by its unique serial number, the Pill automatically detects and distinguishes between all five probes no manual configuration needed.

Think about what five simultaneous temperature readings actually lets you do.

Aquarium and fish keeping.

Monitor water temperature at multiple depths and locations in a tank. Spot temperature gradients that could stress fish, and trigger alerts or automated heaters if readings drift outside your target range.

Greenhouses and growing spaces.

Track temperature at soil level, plant canopy height, and near the roof. Automate ventilation or heating based on real conditions, not a single thermostat reading that might not represent the whole space.

Home brewing and fermentation.

Place probes inside and outside a fermenter, plus in the ambient room. Track fermentation temperature precisely and catch any deviations before they affect your batch.

Server rooms and network cabinets.

Monitor hotspots across a rack or room. Get early warning of cooling failures before equipment overheats. Feed data into your monitoring dashboard alongside your network metrics.

Hot water systems and heating.

Track flow and return temperatures on a heating system, monitor a hot water cylinder at different levels, or compare boiler output against radiator performance.

Food storage and cold chains.

Place probes in fridges, freezers, or cool rooms. Log temperature continuously and receive alerts if anything moves outside safe limits, useful for food safety compliance or simply peace of mind.

The point is that multi-point temperature monitoring used to require expensive industrial equipment or cobbling together multiple standalone sensors with their own apps and batteries. The Pill plus the Splitter gives you a single, unified, WiFi-connected system for a fraction of the cost.

Setting up the Pill is straightforward. Plug it into any USB-C power source a phone charger, a USB port on a router, a power bank, whatever you have to hand. Open the Shelly app (or connect via the web UI), and the Pill appears on your network. Connect your DS18B20 probes either directly or through the Splitter, and the sensors are automatically detected. Readings start flowing immediately.

If you're using Home Assistant or another platform, the Pill integrates via MQTT or HTTP standard protocols that any decent smart home hub already supports. Shelly's Gen3 scripting also means you can write custom logic directly on the device itself, so it can make decisions locally without relying on a central hub.

We stock the Shelly Pill and the 1-to-5 Splitter because they represent exactly the kind of smart home product we look for at DigIoT: genuinely useful, sensibly priced, built on open standards, and not trying to lock you into a single ecosystem.

The Pill fills a gap that's been underserved for a long time. There are plenty of smart temperature sensors on the market, but most are self-contained units with built-in batteries, a single reading, and a dependency on their own cloud service. The Pill takes a different approach it's a bridge that lets you choose your own sensors, connect as many as you need, and feed the data wherever you want it.

Paired with the 1-to-5 Splitter, it becomes a genuinely capable multi-point monitoring system that costs less than most single-sensor smart thermometers on the market.

Whether you're monitoring a fish tank, keeping a greenhouse at the right temperature, or tracking conditions in a server room, the Pill and Splitter combination is a smart, flexible solution that plays nicely with everything else in your home.

Both products are available now in the DigIoT store.
The Shelly Pill and 1-to-5 Splitter are sold separately. DS18B20 temperature probes are also sold separately. The Pill requires a 5V USB-C power source (not included).