1. Project introduction

At present, the common sensor in Mijia is the human body infrared sensor. People are currently in the sensor Lingpu and Ziqing, and there is no action in the headquarters of the Mi family.

Since Xiaomi IOT does not provide chips for sale to individual developers, there are also many human sensors, door and window sensors, and so on on the Internet. The basic features are pretty much the same. It's really not very optimistic in terms of price.

After my whimsical ideas and inspiration from the bigwigs' plans. Came up with the idea of transforming the human presence sensor through the Mijia smart light-sensing night light newly launched by Mijia, which is cheap and moderately functional. It only costs 30-50 yuan.

This plan is partly inspired by Xianyu@狗东的间谍  B站@沈乔治_

QQ group: 713228544

2. Description

This item is divided into Deluxe Edition and Normal Edition.

The Deluxe Edition adopts advanced ACDC power modules, and arranges peripheral security measures and filtering to ensure a more stable and safe power supply.

The standard version uses the most basic components to ensure the normal operation of the circuit.

Control Principle:

The original solution was to use the radar to control an LED to irradiate the photoresistor to achieve the switch, but the heat was severe and the LED could be damaged during use.

Therefore, the scheme has been improved and realized through optocoupler.

The night light used to be able to link the switch of other devices through the luminous flux of the photoresistor, but now the linkage can be realized by changing the photoresistor to the form of optocoupler. The radar detects that someone outputs a high level, gives the optocoupler a signal, and turns on the light. The radar detects that there is no one, outputs a low level, and turns off the lights.

3. Component preparation

Normal version

1. Mijia intelligent light sensing night light MESH.

2. LD2410B radar, choose the Bluetooth version.

3.EL357N optocoupler

4. ACDC power module

5.1K resistor*1, 0603LED*1, cable tie*2, electrical tape, M2*5 screws 4pcs.

Deluxe Edition (on top of the above)

1. ACDC was replaced with HLK-PM01

2.100NF safety capacitors K104K275VC3L3.5

3. Varistor 10D561K

4. Disposable fuse SET T2.5A 250V

5.100UF capacitance

6.common mode choke

4. Magic Change

Comes to 220V strong electricity, please pay attention to the safety of electricity.

Both the adapter board and the 3D enclosure can be printed free of charge.

The adapter plate is 1.2mm.

Solder the radar, resistor, and LED to the back of the adapter board.

Solder the power module and optocoupler to the front of the adapter plate, and fix the power module with cable ties or adhesive tape.

Attach the adapter plate to the 3D housing.

Remove the night light housing, remove the night light resistor, and remove the touch spring.

Connect the power module through the 220V pin of the night light, and connect the optocoupler to the photosensitive pin {photocoupler + on the left side of the photoresistor, and optocoupler on the right side of the photoresistor-}

Isolate the 220V power supply pin and the night light PCB with electrical tape to avoid contact with short circuit.

Install the shell to complete the assembly (I have made the shell bigger, and now the size is normal in the project)

5. Testing

Since there is no night light reset, the night light reset method is still the original long press spring reset. The spring did not long press the original spring contact with tweezers.

Download HLKRadarTool https://www.pgyer.com/Lq8p

IOS is available for download in the store search.

Mi Home is set to turn off the light sensor, automatically turn on the lights, and automate scene settings.

Ambient light - ON XX.

Ambient light and darkness - off XX.

Plug the modified night light into the socket, and after powering on, open the APP to automatically search for the radar signal. Enter your password to log in.

The red circle means there is someone, the pink circle means stationary, and the green circle means no one.

The red line represents the set threshold The blue line represents the energy value of the object, and the light is on when the energy value of the object is higher than the threshold.

Someone LED is detected to be on, and no one LED is off.

You can adjust the parameters according to the test of the entry and exit of the human entity. Specific space adjustments.

There is no moderation here. A sensitivity of 0 is the most sensitive and 100 is the least sensitive.

6. Video

Bilibili：https://www.bilibili.com/video/BV1GR4y1y7Mn/?vd_source=74a9f6cb9a59140477fef67bbb0ec8ee

At present, I have not fully adjusted this, and there is a delay in turning on the lights.