Buying a quality smartphone accessory is always a step towards making the gadget more usable. Redmi 9T owners often choose smart cases that allow them to control the device without opening the lid.
The main difficulty is that a smart case does not require the installation of drivers in the classical sense, as it happens with the periphery for a PC. All the magic lies in the operation of the magnetic Hall sensor built into the accessory lid, and the software reaction of the MIUI operating system. If this bundle works incorrectly, the screen may not go out when closed or, conversely, randomly turn on in the pocket.
In this guide, we will examine all the nuances of the interaction between accessory and smartphone, you will learn where to look for hidden settings, how to calibrate sensitivity and what to do if standard methods do not work.
The Principle of Magnetic Sensor in Redmi 9T
The fundamental basis of the smart case is a physical phenomenon known as the Hall effect. In the end of the case Xiaomi Redmi 9T built a miniature sensor that responds to the change in the magnetic field.
When you close the lid, the magnet comes to the sensor, the field changes, and the sensor sends an electrical signal to the processor. The Android operating system receives an interrupt and initiates a command to lock the screen or go to sleep. When you open the lid, the process is reversed: the magnetic field disappears, and the screen is activated.
It is important to understand that the physical matching of positions is critical for proper operation: if the case is chosen incorrectly or skewed, the magnet may not fall into the sensor sensitivity zone, in which case the system will not receive a signal to close, and the screen will remain on, which will lead to a rapid discharge of the battery and heating of the device in the pocket.
⚠️ Attention: Using cases with too powerful neodymium magnets can cause interference with the compass and navigation modules of the smartphone. Try to use certified accessories where the strength of the magnet is selected specifically for mobile devices.
There is a misconception that this feature requires a case from Xiaomi manufacturer. In fact, most third-party accessories labeled as "Smart Case" or "View Case" use a standard magnet layout. Compatibility issues are rare and most often related to the design features of a particular lid model, rather than software constraints.
Basic configuration through the system menu
Once you install the case on Redmi 9T, the first thing you need to do is check for activation of the corresponding feature in the MIUI shell. By default, this option is often turned on, but after updating the firmware or resetting the settings, it can be deactivated. To access the settings, go to the main settings menu of your device.
The interface of the settings may vary slightly depending on the version of MIUI, but the logic remains the same: you need to find the partition responsible for locking the screen or special features, and that's where the switch that activates the response to close the lid is hidden.
Follow the step-by-step algorithm to activate the function:
- 🔍 Open the Settings app and in the search bar at the top, type the word "pocket" or "case".
- 📱 Go to the Lock Screen section (sometimes in the General Settings or Special Opportunities group").
- ✅ Find the item in your pocket or smart mode and make sure that the slider is lit blue (active).
- 🧪 If possible, run a test: Close the lid, wait 3 seconds, then open. The screen should go out and light up accordingly.
In some versions of the firmware, this option may be called "Pocket Mode," and it's designed not only for cases, but also to prevent accidental tapping when the phone is in a tight pocket of pants without a case, but it's this algorithm that processes signals from the magnetic sensor of the case-book.
Setting up scenarios and automation
Standard settings are sometimes not enough, especially if you want the case to perform more complex actions, such as turning on certain applications when opening the lid or changing the volume. Xiaomi has a powerful tool in its arsenal - the Auto Tasks app (in older versions of MIUI) or integration with Google Home and third-party launchers.
Consider creating a simple script that will be useful to every Redmi 9T user. We will set up automatic bright screen mode or start the navigator when you remove the lock with a case, which makes a regular accessory into a full-fledged element of a smart home.
To create an advanced logic of work, perform the following actions:
- Launch the standard Security app, which is preinstalled on all Xiaomi smartphones.
- Scroll down the tool list to the Tools block and select Auto Tasks.
- Click the add-on button for a new script (usually a plus in the corner).
- In the condition (trigger), select Smart Case or Approximation Sensor Status if there is no direct option.
- In action, specify what is to happen: launch the application, change the sound settings or send a notification.
Automation allows for unique features, such as setting up your phone so that when you close your cover at night, you automatically turn on Do Not Disturb and your alarm, eliminating the need to manually change your settings before bedtime.
⚠️ Note: When creating complex scenarios through Auto Tasks, make sure that conditions do not conflict with each other. For example, if one scenario turns off Wi-Fi and another turns it on when the same action occurs, the system may not work.
Problems with the proximity sensor and their solution
The most common problem that Redmi 9T owners face when using smart cases is the incorrect operation of the proximity sensor. The screen may not go out during a conversation or, conversely, constantly burn in the pocket, causing a “pocket set”. Often the culprit is a protective glass that covers the top of the display.
The proximity sensor in this model is located at the top of the screen, next to the speaker. If you use a solid protective glass (2.5D or 3D) that covers this area, or if you have a low-quality glass paste without a cutout, the sensor will be disrupted. The cover magnet can cause additional interference in this area.
To diagnose and troubleshoot, calibrate the sensor:
- 📞 Open the Phone app and dial the secret code ##64663## to log into the engineering menu.
- 📟 Find the Proximity Sensor test in the list).
- 👐 Put your hand over the top of the screen, then remove your hand.
- 🔧 If the test is not passed, press the Calibration button and follow the instructions on the screen, closing and opening the sensor.
If the software calibration doesn't work, it's worth checking the physical condition of the top of the smartphone. Dirt, grease, or glue residue from the old protective glass can shield the sensor. Gently wipe the speaker area with an alcohol wipe. In rare cases, removing the case and re-installing it with a tighter press at the top helps.
Comparison of smart cases for Redmi 9T
Xiaomi’s accessories market offers many smart cases, which differ not only in design but also in functionality, and understanding the differences will help you choose the best option that will interact correctly with the MIUI system and not cause conflicts.
The main differences are the presence of a transparent window on the back cover and the type of magnetic fastener. Some models have a built-in battery, which is a separate class of devices that require USB connection, but we are talking about classic magnetic cases.
| Type of case | Presence of a window | Compatibility with sensor | Features |
|---|---|---|---|
| Flip with window | Yeah (transparent) | Tall. | Allows you to see time and notifications without opening |
| Book (Book) | No. | Medium | Full protection requires opening up for any action |
| Slim Fit | No. | Low. | A thin, often weak magnet may not wake the screen |
| Original Xiaomi | Depends on the model. | Perfect. | Precise positioning of the magnet, support for themes of design |
When choosing, consider the thickness of the front cover, if it is too thick or made of metallic material (such as a decorative insert), it can shield the magnetic field, in which case the distance between the magnet in the cover and the sensor in the phone becomes critical, and the function may stop working.
FAQ: Frequently Asked Questions
Why does the Redmi 9T screen not go out when the case is closed?
Can I use a case from another Xiaomi model?
Does a smart case affect the battery discharge rate?
How to turn off the reaction to the cover if it interferes?
In conclusion, the precise alignment of the cover magnet relative to the top end of the Redmi 9T is key to the stability of the entire system. Don't be afraid to experiment with the density of the cover if there are failures. A properly configured accessory makes using the smartphone much more comfortable and safer.