Xiaomi Mi 9 (xiaomi-cepheus)

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Xiaomi Mi 9
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Mi 9
Manufacturer Xiaomi
Name Mi 9
Codename xiaomi-cepheus
Released 2019
Category testing
Original software Android 9.0, up to 10, MIUI 11
Hardware
Chipset Qualcomm SM8150 Snapdragon 855
CPU 8-core (1x 2.84 GHz Kryo 485 & 3x 2.42 GHz Kryo 485 & 4x 1.78 GHz Kryo 485)
GPU Adreno 640
Display 1080 x 2340
Storage 64/128/256 GB
Memory 6/8 GB
Architecture aarch64
Features
USB Networking
Flashing
Touchscreen
Display
WiFi
Xwayland
FDE
Mainline
Battery
3D Acceleration
Accelerometer
Audio
Bluetooth
Camera
GPS
Mobile data
SMS
Calls
USB OTG


Contributors

Maintainer(s)

Users owning this device

  • Alexeymin (Notes: Main phone wannabe, Custom ROM - Pixel Experience, no pmOS port)
  • Frankwalter (Notes: Used as main, but a phone is of no use to me. I aim to make it completely mainline.)


How to enter flash mode

Bootloader Unlocking

Like other Xiaomi devices, the user will have to acquire the bootloader unlock key: https://en.miui.com/unlock

The device will not unlock if the device isn't 7 days old (from the time when your device connects to internet and powered on, and linked with Mi Account)

Recovery mode

  • Turn the device off (or restart also works)
  • Hold Volume Up and Power button
  • Once you feel vibration and phone turns on, release Power button
  • Keep holding Volume Up until you get to recovery.

Flashing (Download, Fastboot) mode

  • Same as recovery, but this time hold the Volume Down and Power keys.


Getting logs through debug UART

Tested! It works extremely well and the TX pin is easily accessible even without soldering. For the ground you can force a breadboard pin into some metal shield. Be careful not to break the back being of a glassy material, so use a piece of plastic such as a credit card (not to scratch the metal edges) to unstick the glue in the edges. To get the credit card into the edges you must first heat them with a phono or with a gas stove and then with a suction cup lift the back (opposing the strength of the glue). Never bend the back too much to avoid the risk of breaking it, but it is relatively flexible and always keeping in mind that it is a glassy material you will not have to leave defects, let alone cracks. If you care about aesthetics and plan to combine a mess, I recommend you put a spare back on the cart, they have a paltry price. The image below indicates which are the serial pins, this is the upper board.
Xiaomi-cepheus UART pins.jpg Xiaomi-cepheus-UART-pins-schematic.jpg

Links