Zigbee Presence Sensor With Relay MTG075-ZB-RL Review

Ever since the first generation of smart mmWave presence sensors appeared on the market (Aqara FP1, Tuya ZY-M100), manufacturers started waking up and realized this is a product that people want and need. Many devices released since are just the same presence sensors wrapped in a different case and resold with a markup.

I’ve been on the lookout for new and interesting static human presence sensors since my comparison review of the top 3 available (at the time) and I believe there are a few worth talking about.

For example, this presence sensor features a siren – it goes off whenever there is presence detected. Another example is this cheap version with an illuminance sensor both of which I’ve already bought and waiting for their arrival.

Today’s review is for a very interesting variant of a presence sensor paired with a 16A relay – which turns on the lights (or anything attached) once motion is detected and vise versa.

This model is labelled as MTG075-ZB-RL by the manufacturer and identified as _TZE204_dtzziy1e within the Tuya ecosystem, available with both 5.8GHz and 24Ghz radar sensors inside. I’m testing the 24GHz radar variant, which can be bought on AliExpress for ~$20, it’s not yet available on Amazon.

Technical Specification

• Model: MTG075-ZB-RL
• Manufacturer ID: _TZE204_dtzziy1e
• Connectivity: ZigBee / WiFi
• Input: 85-240VAC.
• Sensitivity: 1-9(default 7)
• 5.8G Beam Angle: 120X120°
• 24G Beam Angle: 110X110°
• 5.8G Sensing Distance: 0-11m(default 6m)
• 24G Sensing Distance: 2.5-10m(default 7m)
• 5.8G Sensing Radius: 2.5-3m(Presence), 4～5.5m(motion).
• 24G Sensing Radius: 2-3m(Presence), 4～4.5m(motion).
• Illuminance Sensor: 0～500 Lux
• Departure Delay: 0.5s～25 min
• Transmitting Power: 3～5 dBm(5.8G), 10dBm(24G).
• Working Temperature: -10°C~+50°C
• Working Humidity: 5～90% RH(No Condensation).
• Protection Level: IP20.
• Relay Load: Resistive load≤3000W LED≤300W.
• Size: ⌀105mm*28mm/⌀4.13inch*1.1inch

Difference between 5.8GHz vs 24GHz versions

This presence sensor is sold in both 5.8GHz and 24GHz radar variants. Even though 5.8GHz is technically microwave and not millimeter wave, it operates the same way 24GHz does.

It emits electromagnetic waves with the help of a transmitter which are reflected back to the sensor, a parameter known as the echo time. The receiver in the sensor then analyses the waves that are bounced back and the sensor is triggered/cleared. In summary:

• 24GHz has higher sensitivity
• 24GHz has more accurate departure delay (presence clearance) time. For example:
  • If you set the departure delay to 30sec on a 24GHz radar, the occupancy will be cleared after 30sec + 1-2 seconds.
  • If you set the departure delay to 30sec on a 5.8GHz radar, the occupancy will be cleared after 30sec + 5-8 seconds.
• 24GHz has higher recognition accuracy (less false triggers)
• 24GHz has shorter detection distance than 5.8GHz
• 5.8GHz is limited when used in metal containers (eg. elevators)

For the purpose of monitoring presence in a room, both versions will do a good job. However, I would go for the 24GHz sensor as it’s more powerful and can be fine-tuned better in terms of sensitivity and delay.

Teardown

The Tuya MTG075-ZB-RL came in a package with a user manual, a set of screws and a sticker for installation. The box was banged up as usual, but the device intact. No cables are included, as this is meant to go on your ceiling and mains powered (85-240VAC).

The device has a very convenient shape for ceiling installation, it’s flat and thin which makes it look good once mounted in place. It does not require drilling a hole like the ZY-M100 did.

On the backside, some information about the device is printed between the two holes used for ceiling installation. The bigger hole on the bottom is where the cables go, so they are hidden from sight.

Opening up the device reveals all the components of the main PCB. Starting with the actual mmWave presence sensor in the middle, the communication module on one side and relay and terminals on the other.

The terminals are plastic push-in clips which grip the wire once released. Some people prefer these because they are fast to use and don’t have screws. I much prefer screw terminals, because once I install a wire I can be confident it won’t get loose.

The 16A relay used to control the lights (or anything that’s attached to it) is model HF32FV-16 [Datasheet] manufactured by Hongfa Technology in China. I’ve encountered a 10A version of this relay in the Aqara S1E Magic Switch.

The actual mmWave radar sensor is labelled as model S3KM111L [Datasheet] manufacturer by ICLegend Micro, a company from Shenzhen in China, specializing in RF sensors.

According to the datasheet, this is a 24GHz capable sensor with 1GHz bandwidth modulation, specifically designed for the smart home industry with a secondary application in robotics and vital signs monitoring.

Communication is handled by a Tuya ZS3L Module [Datasheet], a chip I’ve encoutered many times when testing smart devices. More recently, I found it powers the Tuya ZS06 IR Blaster and Tuya PJ-MGW1203 Single Clamp Energy Meter.

This module is based on the latest gen EFR32MG21 [Datasheet] SoC by Silicon Labs, so I expect no communication issues and timely responses, which are crucial in a presence sensor.

Installation and Wiring

This presence sensor is very simple to wire and install, the terminals are the same like in any smart switch. There are a total of 4 terminals, two for input (IN L+N) and two output (OUT L+N). Remove the top cap by twisting it sideways:

• Insert the wires through the hole to hide them
• Wire the L-Live wire to the L-In terminal of the device
• Wire the N-Neutral wire to the N-In terminal of the device
• (Optional) Wire the L-Out and N-Out terminals to the L and N wires of your light

Once you’ve connected everything, you can proceed to install the sensor on your ceiling. I did not use the screws, since my testing location (hallway) was not my final installation location. I simply used the sticker and it stayed in place, the device is not very heavy. Here’s an image from the user manual:

Home Assistant Integration

The Tuya Zigbee Presence Sensor with a relay MTG072-ZB-RL is supported in Home Assistant through Zigbee2MQTT v1.33.0. ZHA support in currently in development which you can follow here.

To pair the device in Zigbee2MQTT, twist the top cap of the case counter-clockwise and press the pairing button until the indicator LED starts blinking red.

Zigbee2MQTT

Once paired to Zigbee2MQTT, it’s identified correctly as model MTG075-ZB-RL and manufacturer _TZE204_dtzziy1e. Since the device is mains powered, it’s also a Router capable or relaying Zigbee traffic from adjacent devices. It exposes the following entities:

Each of these is used to tweak and fine-tune the operation of the device. Since they can be a bit confusing in understanding what exactly they do, here’s my best effort to explain those that are not self-explanatory:

• Radar Sensitivity (default: 7, range: 0-9)
  • Adjusts the main sensitivity of the sensor
  • Used for continuous presence detection
  • Used for reducing/eliminating false triggers
• Entry Sensitivity (default: 7, range: 0-9)
  • Sensitivity threshold for the first time a target enters the detection area
  • Used for initial presence detection, can be different from the main Radar Sensitivity
  • Used for reducing/eliminating false triggers
• Detection Range (default: 6m 5.8G/7m 24G, range: 0-10m)
  • The maximum detection distance of the sensor
  • At 10m, sensitivity is automatically reduced
  • Used for reducing/eliminating false triggers
• Shield Range (default: 0m, range: 0-10m)
  • The nearest distance detected by the sensor during operation
  • The value must be lower than Detection Range
  • Used for reducing/eliminating false triggers in it’s near vicinity
• Entry Distance Indentation: (default: 0.6m)
  • This parameter is used for indenting the detection distance of the sensor inwards
  • Used for reducing/eliminating false triggers
• Entry Filter Time (default: 0.1s)
  • Time threshold for the initial detection once a target enters the detection area
  • Used for reducing/eliminating false triggers when sensor first detects motion
• Departure Delay (default: 15s, range: 0-1500s)
  • This is a motion clearance timer, which holds the state of the sensor to occupied for the set duration
  • By default, it will clear presence after 15s but can be set from 0-1500s
• Block Time (default: 2.5s)
  • Block time is used to add a delay for re-detection when the occupancy goes from True to False
  • Adding X seconds, the sensor will not detect presence again until he timer expires
  • Used for reducing/eliminating false triggers caused by edge interference
• Illuminance Threshold (default: 420, range: 0-420)
  • The illuminance threshold is used when the Breaker Mode is set to local. The illuminance level set here determines whether the relay will be triggered once motion is detected.
  • If the illuminance value is bellow the preset threshold, the relay is turned on/off normally
  • If the illuminance value is above the preset threshold, the relay will not be turned on/off, regardless of detected presence
• Breaker Status:
  • Switch for operating the relay when in Standard mode
  • Indicator for relay status when in Local mode
• Breaker Mode:
  • Standard: Can be remotely controlled through Zigbee2MQTT/Home Assistant
  • Local: Is controlled only through motion detection preconditioned with the Illuminance threshold. Automatically turns ON/OFF the relay.
• Status Indication:
  • Turns ON/OFF the LED indicator, which lights up when the sensor is triggered by default

Testing

Once I added the device to Zigbee2MQTT from my workbench, I tinkered with it’s parameters to get an idea of how it operates and what each parameter does. This device can be very confusing to setup initially, but once you get a general understanding of the settings available it’s one of the most tweakable presence sensors out there.

I used a sticker and installed the device in my hallway, attaching the ceiling light to the relay terminals. It provided me with a nice visual indicator of the detection/clearance speed of the Tuya MTG075-ZB-RL Presence Sensor. Here are my findings so far:

• The device trigger time is instant with Entry Filter Time set to 0.1 (default)
  • Great for triggering automations
• The device presence clearance time is respected by the parameters set in Zigbee2MQTT
  • The Departure Delay goes as low as 2s (presence clear), although it’s recommended by the manufacturer to not go lower than 15s as it can cause false negatives
  • The Block Time (a time interval for re-detection) can be lowered to 1.5s maximum. I found 10s works perfectly
• The initial presence detection respects the following parameters:
  • Entry Sensitivity
  • Detection Range
  • Entry Filter Time
  • Entry Distance Indentation
• The continuous presence detection respects the following parameters:
  • Detection Range
  • Radar Sensitivity
  • Shield Range
• The relay is triggered instantly when presence is detected with the Breaker Mode set to Local
• The device suffers from the same interference sources as other mmWave presence sensors
  • Fans (Air Fans, PC Case Fans, Ceiling Fans)
  • Air Conditioning (Swing)
  • Rolling Shutters/Shades
  • Animals (Pets)
• The target distance is inaccurate, in my estimate by an offset of 30%
• The Radar sensitivity needs to be lower than 9, which is way to high and produces false positives. I found 6-7 works perfectly for me
• The Illuminance reading is very responsive, but somewhat inaccurate. It’s only relevant if you use it as a precondition for triggering the relay
• The Detection Range parameters is not absolute. For example, if you set the range to 3 meters, the sensor can be triggered ±1 from the preset value. This is considered normal and can also cause false negative triggers within 1 meter of the parameter value.

Summary

If you are looking for a ceiling presence sensor, this Tuya model MTG075-ZB-RL is the way to go. The previous model I reviewed, the Tuya ZY-M100, required a hole in the ceiling in order to install it. This one is non-invasive, meaning you can attach it to any ceiling in your home.

Zigbee connectivity was rock solid, paired to the Sonoff ZBDongle-E and Zigbee2MQTT. It’s worth noting that I have a pretty robust mesh network, with every device reporting a LQI of over 200.

Getting the device in optimal state to avoid any false positive and negative triggers can be a challenging task. I’ve found this to be true for any presence sensor I’ve tested so far, not just this Tuya model MTG075-ZB-RL.

I appreciate the two separate sets of parameters available for tweaking the device: one for the initial presence detection and the other for the continuous (static) presence detection. This allows for a more versatile usage of the device and more room for eliminating false triggers.

Overall, I’ve had a good experience with the Tuya MTG075-ZB-RL. I experienced a couple of false positive triggers before I found the optimal parameters, but no false negatives.

Pricing and Availability