LinknLink’s eMotion range promises to bring mmWave presence sensing into your home, with both the eMotion Max and eMotion Pro. I had the chance to test both devices and integrate them with Home Assistant. Here’s what I found.
What is a mmWave Sensor?
Most traditional motion sensors used in smart homes rely on Passive Infrared (PIR) technology. PIR sensors detect changes in heat within their field of view — when a warm body (like a person) moves across the area, the sensor triggers. They’re simple, inexpensive, and effective for motion-based automations like turning lights on when someone walks into a room.
However, PIR sensors have a big limitation: they only detect motion, not presence. If you sit still on the couch reading a book, a PIR sensor often assumes you’ve left and turns the lights off. That’s where mmWave (millimeter-wave radar) sensors come in.
mmWave sensors work by emitting high-frequency radio waves and measuring how they bounce back. Subtle movements — like breathing or shifting in your chair — create tiny changes in the reflected signal, allowing the sensor to detect that someone is still there, even when perfectly still.
Beyond just detecting presence, some advanced mmWave sensors can:
- Track multiple people in different zones of a room
- Estimate distance and direction of movement
- Provide near-instant response times for entering/leaving detection
The trade-off? mmWave sensors can sometimes detect through walls or glass, requiring careful placement and tuning to avoid false positives. Moving objects like fans can also cause a room to never be marked as unoccupied.
First Impressions
Out of the box, both devices are lightweight and sleek. Side by side, it’s hard to tell the eMotion Max and eMotion Pro apart — they share the same minimalist design and USB-C power input. Mounting is via a clever but slightly tricky 3M adhesive system. The device sticks to a mount, which itself adheres to the wall or ceiling. While this works well for most scenarios, it isn’t flexible: remove it once, and the adhesive may not stick again, making repositioning a challenge. You'll also take off some paint from your ceiling or wall (don't ask me how I know).
The adhesive mounting has an additional quirk — once you plug in the USB-C cable, you can’t easily remove it without taking the mount off. That’s something to keep in mind if you anticipate changing positions or need to switch out the cable at some point.
Setup Experience
Both devices require the LinknLink app, which asks for your email, your country, and even your town. I assume the town is used for some location-specific stuff like weather. The app also mentions that your Wi-Fi credentials will be stored on the device and in the cloud. There’s no way to opt out, which may be a concern for privacy-conscious users.
The eMotion Max sets up over Wi-Fi, while the eMotion Pro uses Bluetooth. Setup was mostly straightforward, but the app can be clunky: MQTT details are not remembered, meaning you have to re-enter broker information for each new device.
Home Assistant Integration
Once paired, both devices integrate with Home Assistant via MQTT. MQTT discovery works out of the box, though custom topics are not supported. Each sensor exposes:
- A binary presence sensor
- Zone sensors for tracking people in specific areas
- Distance/proximity sensors
- Event sensors for entering and leaving rooms
The binary sensors support a delay-off timer, which keeps the room “occupied” for a short while after someone leaves. For immediate reactions, Home Assistant can use the leave event to trigger automations instantly, or you can adjust the leave timeout in the LinknLink app.
eMotion Max Performance
The eMotion Max does a great job detecting a single person. Multi-person detection, however, is where the Max struggles. Zones will often go inactive when more than one person is present, even if the app map shows people in the correct spots. If you're entertaining or have a lot of people moving over many zones, it gets hard to rely on the accuracy of what this device is reporting.
If you're using this sensor with MQTT and Home Assistant, you might be able to get some better results that what the LinknLink app can do itself. In some situatios I found MQTT reporting person counts per zone, so Home Assistant users can workaround the limitation using template binary sensors to restore zone-based automation.
Like other mmWave sensors, the sitting still detection can be a problem. Multiple times my wife and I would be sitting on the couch directly near the eMotion Max, and the device would not see anyone in any of the zones. This is very similar to other mmWave sensors I've been experimenting with, and feel this is a limitation of the mmWave sensors more than the LinknLink product itself.
Zone setup in the app is straightforward: a drag-to-draw interface allows up to 4 zones, more than most multi-zone sensors on the market. Response time to someone entering the room is a bit slow (typical for mmWave sensors), but overall, it’s stable once triggered.
eMotion Pro Performance
The eMotion Pro doesn't have multi-zone support like the eMotion Max, however it does support distance sensing, letting you know how close someone is to the device — though it cannot detect direction.
Entry and exit detection was fast. Like the eMotion Max, events are exposed via MQTT, allowing immediate reactions in Home Assistant. Like other mmWave devices, the Pro can sometimes detect people through walls. This was solved in my laundry by setting the detection range to short, which avoids false positives without compromising in-room detection.
Real-World Use & Observations
Both devices work well at single-room presence detection. I would put these on-par with the Aqara FP1 sensor (I haven't tested the newer FP2 devices yet).
Multi-room and multi-person tracking on the eMotion Max are inconsistent. For example, if one person is in Room A and another in Room B, the sensor might drop the person in Room B. In spaces with 5 or more people, zone reliability diminishes further. These are worth noting if you’re aiming for occupancy-based automations in larger rooms or open-plan spaces. If you're thinking you can detect people in multiple rooms with one device - as advertised - I don't think this is the device for you.
Privacy & Local Control Considerations
While initial setup depends on the cloud, once integrated via MQTT, both devices can operate locally, meaning automations in Home Assistant do not require ongoing cloud access. That said, the mandatory cloud storage of Wi-Fi credentials may still deter privacy-focused users.
As the host of the Home Assistant Podcast, I've seen many devices turned into paper weights thanks to companies going under, or their products costing them money to service. The LinknLink devices require an app from a manufacturer, and the devices need to initially connect to their cloud servers to operate. Unlike a Zigbee, Zwave or ESPHome device, there is always a risk that the LinknLink app may not be available in the app stores one day, and these devices are then destined for your local e-waste collection point.
Together with Rohan Karamandi, hear me break down the latest Home Assistant release and talk with other users of Home Assistant across the open-source community.
Comparing Other Brands
I took a look at some of the other mmWave sensors in comparison:
| Product | Price |
|---|---|
| eMotion Pro | $25.90 |
| Apollo Automation MSR-2 | $37.99 |
| eMotion Max | $39.90 |
| Apollo Automation MTR-1 | $39.99 |
| Aqara FP1E | $50.99 |
| Everything Presence One | $63.68 |
| Aqara FP2 | $85.99 |
The Apollo Automation MSR-2 would be a direct contender against the eMotion Pro (no zone detection) and the MTR-1 with the eMotion Max. I know the Everything Presence and Apollo Automation devices are popular with the Home Assistant Community. In terms of build quality, the eMotion devices from LinknLink feel more superior. The Apollo devices are 3D printed (they also make these 3D print files available) whereas the eMotion devices are not.
Bottom Line
These two motion sensors are very competitively priced, and have some aesthetic pros over some competitors from Apollo Automation and Everything Smart Technology. However there are some drawbacks:
- Propriety application for onboarding and administering the device
- Requirement to send WiFi credentials to a cloud server
- The MQTT integration with Home Assistant is great and is designed for Home Assistant's MQTT device discoverability. However changing this behaviour under the hood for yourself is limited (ie no custom MQTT base topics)
- Like the EP One and Apollo Automation ESPHome based sensors, these are WiFi devices which require a constant power source. There is no Matter or Thread support for this device, so integrating with Home Assistant today is limited to MQTT.
If you haven't used a mmWave sensor before and want to dip your toes in, these are worth a look. The design of these feel more polished than some of the 3D printed options out there. The 3M mounting could be improved.
I still feel multi-room support for mmWave devices is great in theory, but no one has mastered it yet.
You can get the eMotion devices on Amazon below:
