How to add Xiaomi hygrometer to the ecosystem of a smart home: instructions with photos and videos

Xiaomi’s hygrometers have long been the standard for monitoring the microclimate in apartments, greenhouses and offices. These compact devices not only show current humidity and temperature, but also integrate into the Mi Home ecosystem, allowing you to automate climate control along with humidifiers, air conditioners and heaters. However, many users face problems when they first connect: the sensor is not detected by the application, shows incorrect data or falls off after a few days.

In this article, we will analyze all current models of Xiaomi hygrometers (including new ones). LYWSD03MMC Bluetooth 5.0 and CGDN1 With e-ink display, we will describe in detail the process of adding to Mi Home and alternative platforms like Home Assistant, as well as reveal hidden calibration settings that the manufacturer does not advertise. We will focus on common errors, such as why the sensor can show 99 percent humidity in a normal room or why it stops updating data after moving.

1 What models of Xiaomi hygrometers exist and how they differ

Xiaomi (and its sub-brand Aqara) have produced more than 10 models of hygrometers in the past 5 years, the main differences are in the communication protocol, sensor accuracy and additional features.

For most users, the best choice is LYWSD03MMC — It combines high precision, long battery life and support for all popular smart home platforms. CGDN1 You should consider if you need a Zigbee protocol to integrate with systems like Home Assistant or the likes of a Zigbee protocol. Zigbee2MQTT.

⚠️ Note: Older models like this LYWSDCGQ (2018) are not officially supported by new Mi Home versions, and can only be connected via third-party firmware or Home Assistant.

2.Preparation for Connection: What to Do Before Adding to Mi Home

Before adding a hygrometer to the application, follow a few mandatory steps, which will help avoid most errors associated with incorrect device definition or constant communication interruptions.

• 📱 Update the Mi Home app: Outdated versions (below 6.5.0) do not support new hygrometer models. Download the latest version from Google Play or the App Store.
• 🔋 Check the battery: Even if the hygrometer is new, remove the protective film from the battery (in models with a new battery). CR2032) Or recharge the built-in battery (y) CGDN1).
• 📶 Make sure you have stable Bluetooth: Xiaomi Hygrometers connect to the BLE, Therefore, the distance to the smartphone should not exceed 10 meters, and between the devices should not be thick walls or metal obstacles.

If you are planning to use a hygrometer with a Home Assistant or Zigbee2MQTT, extra-prepare:

• 🖥️ USB Bluetooth adapter (e.g., Bluetooth adapter, CC2540 or ESP32) model BLE.
• 🔌 Zigbee Hub (for example, Aqara Hub) M2) for CGDN1.

Remove the protective film from the battery

Update Mi Home to the latest version

Select the "China" region in the settings

Place the hygrometer no further than 5 meters from the phone

Close all background applications that interfere with Bluetooth

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⚠️ Warning: If you connect the hygrometer through Home Assistant, pre-disconnect it from Mi Home! simultaneous operation in two systems will lead to data conflict and permanent communication breaks.

3. Step-by-step instructions: how to add a hygrometer to Mi Home

The process of adding a hygrometer to the official Mi Home app takes no more than 5 minutes if done correctly. Follow the instructions below to avoid typical errors such as "device not found" or "failed to connect."

1. Open Mi Home and go to Add Devices. Click on the icon + top-right → Choose Add the device → category Sensors → Thermohygrometer.
2. Activate the hygrometer pairing mode. LYWSD03MMC/MJWSD05MMC: Hold the button on the back panel. 5 - Just a few seconds before the light flashes. CGG1: Take the back cover off and press the little button next to the battery. CGDN1: Hold the button on the front panel. 10 seconds.

If the hygrometer is not detected, try:

• 🔄 Restart the phone and try again.
• 📱 Use a different smartphone (sometimes it helps to change Android to iOS or vice versa).
• 🔋 Replace the battery with a new one (even if it seems to work).

⚠️ Attention: After adding a hygrometer to the Mi Home, the data on its display can be updated with a delay of up to 5 minutes. This is normal - this is how energy saving mode works. To get an instant reading, press the button on the case.

4. Alternative ways of connecting: Home Assistant and Zigbee2MQTT

If you’re using Home Assistant or other smart home systems, connecting a Xiaomi hygrometer will require additional steps.

Connection via Bluetooth (for the purpose of) LYWSD03MMC, CGG1)

To integrate Bluetooth Low Energy hygrometers into Home Assistant, you will need:

1. USB Bluetooth adapter (recommended) ESP32 or CC2540).
2. Installed component esp32_ble or ble_monitor.

Add the following lines to the configuration.yaml file:

sensor:


- platform: ble_monitor




devices:




- name: "Bedroom Hygrometer"




mac:"XX:XX:XX:XX:XX:XX"# Replace with MAC- your sensor address




restore_state: true




temperature:




name: "Temperature"




humidity:




name: "Humidity"




battery:




name: "Battery charge"

To find out MAC-Hygrometer address, use the nRF Connect application (Android/iOS) terminal-mate:

hcitool lescan

Connection via Zigbee (for the purpose of CGDN1)

Model CGDN1 It supports Zigbee, which makes it compatible with the:

• 🏠 Aqara Hub (official support).
• 🖥️ Zigbee2MQTT (firmware).
• 🌐 Home Assistant with Integration ZHA.

To connect through Zigbee2MQTT:

1. Make sure you have a Zigbee Coordinator installed (e.g., a Zigbee Coordinator, CC2531 or ConBee II).
2. Activate the conjugation mode on CGDN1 (Hold the button for 5 seconds).
3. In the web interface Zigbee2MQTT Press Permit join and wait for the new device to arrive.

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If the hygrometer CGDN1 If you don't see it through Zigbee, try resetting it to factory settings: hold the button for 20 seconds until the display blinks three times.

Comparison of connection methods

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For maximum stability of the hygrometer in the smart home, it is recommended to use Zigbee (if the model supports) or Home Assistant with a local Bluetooth adapter.

5. Hygrometer calibration: why data can be inaccurate

Even Xiaomi’s new hygrometers can show 5 to 15 percent over- or under-humidity, which is due to sensor manufacturing and storage conditions, and fortunately, most models support manual calibration.

5.1 How to check the accuracy of the hygrometer

To test the accuracy, use the salt method:

1. Pour some warm water into a sealed container (such as a jar).
2. Add salt (proportion: 1 part salt to 4 parts water) and stir until dissolved.
3. Place the hygrometer in the container, close the lid and wait 6-8 hours.
4. The ideal humidity in this environment is 75 percent, and if your sensor is reading a different value, you need to calibrate it.

⚠️ Note: Do not use wet towels or steam for the test - this creates a humidity of 95-100%, which can damage the electronic components of the hygrometer with prolonged exposure.

5.2 Calibration via Mi Home

The official Mi Home app doesn’t provide any calibration tools, but there’s a workaround:

1. Go to the hygrometer settings in Mi Home.
2. Click on three dots in the upper right corner → About the device → Reset.
3. After reset, place the sensor next to the reference hygrometer (e.g., Xiaomi). CGDK2 or professional appliances) for 24 hours.
4. If the difference in readings persists, use the correction factor in automation (for example, in Home Assistant, add offset to the humidity value).

Calibration via Home Assistant

In Home Assistant, you can adjust the hygrometer readings with the template sensor. Add to configuration.yaml:

sensor:


- platform: template




sensors:




humidity_calibrated:




friendly_name: “Humidity (adjusted)”




unit_of_measurement:"%"




value_template:"{{ (states('sensor.lywsd03mmc_humidity') | float + 5) | round(1) }}" # Add +5% to the original value

Replace. + 5 on your correction (may be negative if the sensor overstates the values).

Typical problems and their solutions

Even after successful connectivity, Xiaomi hygrometers can behave in an unstable way, and here is a list of the most common problems and specific ways to solve them, proven in practice.

6.1 The hygrometer shuts down after a few days

If the sensor disappears from the Mi Home or stops updating the data, the reasons may be as follows:

• 🔋 Battery expires: Replace it with a new one (even if the indicator is 50%). Use Panasonic or Duracell batteries, which last longer.
• 📶 Weak Bluetooth signal: Move the hygrometer closer to the phone or hub (maximum distance – 10m without obstacles).
• 📱 Conflict with other devices: In Bluetooth phone settings, “forget” all unnecessary devices (earphones, fitness bracelets).
• 🌐 Xiaomi Cloud Problems: Restart the Mi Home app or reinstall it.

Temperature and humidity readings not updated

If the data on the hygrometer display and in the application are frozen:

1. Press the button on the sensor case - this will force the readings to be updated.
2. Remove the battery for 30 seconds, then insert it back.
3. In Mi Home, remove the device and add it again.

For models LYWSD03MMC and CGDN1 It will also help to update the firmware through Home Assistant:

esp32_ble:


scan_parameters:




active: true




devices:




- mac:"XX:XX:XX:XX:XX:XX"




update_interval: 300 # Update every 5 minutes

The hygrometer shows unrealistic values (e.g. 0% or 100%)

Extreme indications usually indicate:

• Sensor malfunction: Try resetting the device to factory settings (hold the 15-second button).
• External interference: Keep the hygrometer away from heat sources (batteries, cookstoves) or cold (air conditioning).
• Software glitch: Update your firmware through Mi Home or Home Assistant.

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If the hygrometer LYWSD03MMC It shows the temperature at 2-3.°C above the real one, place it 10 to 15 cm from the wall, and the body heats up from nearby surfaces, distorting the data.

Table of errors and decisions

7 Automation: How to Use Hygrometer Data in a Smart Home

The main advantage of Xiaomi hygrometers is the ability to integrate into smart home scenarios. Below are some practical examples of automation that can be configured in the Mi Home or Home Assistant.

Automatic control of the humidifier

Scenario: If the humidity drops below 40%, the Xiaomi Smartmi humidifier is turned on.

At Mi Home:

1. Go to Automation. → Add → If.
2. Select the condition: Humidity < 40% (source: your hygrometer).
3. Action: Insert the humidifier → Select the device.
4. Add a 30 minute delay so that the humidifier doesn't turn on too often.

At Home Assistant:

automation:


- alias: "Low humidifier"




trigger:




platform: numeric_state




entity_id: sensor.lywsd03mmc_humidity




below: 40




action:




service: switch.turn_on




entity_id: switch.xiaomi_uvlazhitel

7.2 Critical alerts

Set up notifications if the humidity or temperature is outside the normal range, such as:

• 📱 In Mi Home: Create Automation with Humidity > 70% and action Send notification.
• 🔔 Home Assistant: Use notify to send push messages or SMS.

Example of code for Home Assistant:

automation:


- alias: "High humidity warning"




trigger:




platform: numeric_state




entity_id: sensor.lywsd03mmc_humidity




above: 70




action:




service: notify.notify




data:




message: "Attention! The humidity in {{ trigger.to_state.attributes.friendly_name }} has exceeded 70%!"

Logistics of data for analysis

To track the climate change in a room over a long period, set up a record of data in:

• 📊 Mi Home: Reading history is stored for 30 days (available in the device schedule).
• 📈 Home Assistant: Use Recorder or InfluxDB to chart.
• 🌐 Third-party services: Export data to Google Sheets using AppDaemon.

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To accurately monitor the microclimate, place the hygrometer at a height of 1-1.5 meters from the floor, away from direct sunlight and drafts, this minimizes measurement errors.

8. Frequently Asked Questions (FAQ)