Owning a Xiaomi smartphone involves not only using advanced CPU features, but also interacting with accessories that extend the functionality of the device. One of the most popular additions is smart cases equipped with magnetic Hall sensors, which allow you to automatically lock the screen when you close the lid and wake the device when you open it, saving battery power and preventing accidental taps in your pocket.
However, many users are faced with a situation where after installing the new protection system does not recognize the magnet, and the screen continues to burn in a closed state, the problem can be in the software settings of the MIUI shell or HyperOS, and in the physical location of the magnet in the accessory. Understanding the principle of operation of the Hall sensors will help you quickly fix the malfunction.
In this article, we will take a closer look at the Smart Case activation algorithm, the calibration features for different Redmi and POCO models, and why cheap accessory copies may not work properly. You will learn to distinguish between software failures and physical defects so that your smartphone reacts to the movements of the cover instantly and seamlessly.
The principle of the Hall sensor in Xiaomi smartphones
The fundamental basis of any smart case is a Hall sensor built directly into the smartphone board, usually at the top of the display or next to the front camera. This tiny element responds to changes in the magnetic field. In the top of the quality case, a small neodymium magnet is built in, which, when closed, creates a field that is captured by the sensor.
When the magnet approaches, the sensor sends an electrical signal to the processor, which initiates the screen to go to sleep, and when the lid is opened, the magnetic field disappears, and the system unlocks the display. It is important to understand that in order to work correctly, the distance between the magnet in the case and the sensor in the phone must be minimal.
⚠️ Attention: Using cases with too thick a back wall or metal inserts in the upper frame area can shield the magnetic field, which makes the Hall sensor no longer respond to the cover closing.
Modern Xiaomi models often use complex magnet layouts to determine not only the fact of closure, but also the position of the case (for example, for the Smart View function, when time is displayed in the window).
Why do magnets sometimes demagnetize?
Activation of the function in the system settings MIUI and HyperOS
In most cases, after installing the original or certified case, Xiaomi’s Android shell system will recognize the accessory automatically. However, if this does not happen, you need to manually check the status of the function. The path to setting up may vary slightly depending on the firmware version, but the logic remains the same.
First, you need to go to the main settings menu. Find the partition that locks the screen. In newer versions of HyperOS, this item is often hidden inside the Always On and Lock menu. This is where the switch is located, which forcefully activates the Hall sensor poll.
☑️ Checking the activation of the smart case
If you can't find the right item, search by settings, type "Cover" or "Smart Case" into the search box, and the system will suggest you go to the desired menu, and make sure the switch is blue or green, which indicates its active state.
Sometimes, when you update the firmware, you reset the settings to the factory ones, and then even the case that you used will stop working until you turn on that option again, which is the normal behavior of the MIUI security system.
Calibration of the sensor and elimination of false positives
When the screen goes out on its own or doesn’t respond to closing, it often requires calibration. Xiaomi smartphones don’t have a separate magnet calibration app available to the average user, but there are engineering menus and hidden tests that help diagnose the problem.
To test the sensor, you can use a special code in the Phone app, and if you type ##6484##, you'll be taken to the CIT engineering menu, and you'll find a test that's connected to the Hall Sensor or magnetic sensor, and if you hold the magnet to the top of the screen, the values should change.
If the sensor is responding in the test, but the case is not working normally, the software logic of the signal processing may have gone wrong, in which case resetting the system settings, but not the data, helps. Go to Settings → About Phone → Resetting → Reset all settings. This will return the system settings to the original, without deleting your photos and applications.
| Symptoms. | Possible cause | Method of decision |
|---|---|---|
| The screen does not go out when closed. | Weak magnet in the case | Replacement of the cover with the original |
| The screen goes off spontaneously. | A third-party magnet in your pocket | Checking environments and accessories |
| The case is unstable. | Magnetization of speakers | Demagnetization or resetting |
| Smart View window is not working. | Incompatibility of the model | Checking the compatibility of the cover |
💡
If the Hall sensor is not working properly, try putting the phone on a flat surface and slowly opening and closing the cover several times, which sometimes helps the system recalibrate the magnetic field threshold.
Compatibility problems of original and copy covers
Xiaomi's accessories market is full of offerings, and not all of them are equally good. Original cases like the Mi Flip Cover or Redmi Note Protective Case are designed with the magnets in place and have the right traction force. Copies are often sinned by the fact that the magnet is not where it is needed or its strength is insufficient.
One of the common problems is using cases from other models. For example, the case from the Redmi Note 10 can physically fit on the Redmi Note 11 in size, but the magnetic tag will be 2-3 millimeters below the sensor, as a result, the smart lock function will not work.
Also worth considering is the fabrication material. Silicone and plastic cases usually do not interfere with the sensor, but cases with metal plates for mounting in the car or with card pockets located on the back cover opposite the sensor can cause interference.
If you have a third-party case that doesn't work, try moving it up or down slightly when you close it, and if the screen goes out in some position, it's the magnet's shifting relative to your smartphone case.
Impact of Third-Party Applications and Launchers
Sometimes the feature conflict is not the case itself, but the software that controls the lock screen. Third-party launchers or Lock Screen apps can intercept control of the Hall sensor, ignoring the system settings of the MIUI.
If you have installed an app for a beautiful lock screen, check its settings. There should be a clause that allows you to work with smart cases. If there is no such item, or the application has been written for a long time and has not been updated, it can block the work of the regular sensor.
Also, some battery-saving apps aggressively (aggressively) manage background processes and can "sleep" the Hall sensor survey to save energy, leading to delays in the response of the case.
⚠️ Note: When using custom firmware (Custom ROMs), the functionality of the smart case can be reduced or absent if the developer has not included the appropriate drivers in the kernel of the system.
For diagnostics, try running your phone in Safe Mode, and if it starts working correctly, it means that the problem is in one of the apps you installed, and remove the recently installed programs one by one, checking the result.
Mechanical damage and sensor repair
In rare cases, the problem lies with the smartphone itself. If the phone was hit or dropped, the plume connecting the board to the side button or sensors could move away. In some Xiaomi models, the Hall sensor is placed on a separate plume of a flexible printed circuit board (Flex cable).
Not only can the case be affected by hardware failure, but the compass or navigation can also be affected, because these systems often use adjacent magnetic field sensors. If the compass in the cards is not working properly, the magnetic sensor is likely to be damaged.
Replacing the sensor requires disassembling the device, which takes a little time in service centers, as the entire plume assembly with volume and switch on is most often changed, and self-repair without experience is not recommended because of the risk of damaging the display plume.
💡
If neither the replacement of the case, nor the reset, nor the check in safe mode did not help - a hardware malfunction of the Hall sensor or its plume is likely, requiring the intervention of the service center.