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=== (Hard) UART ===
=== (Hard) UART ===


The test points are tiny.
Necessary: reasonably fine soldering iron tip, steady hand
Highly recommended: microscope, steadier hand


* Disassemble the phone. [https://youtu.be/xWvFOEW-n1o Here]'s a decent video.
* Disassemble the phone. [https://youtu.be/xWvFOEW-n1o Here]'s a decent video.
Line 105: Line 106:
* After removing the glass, remove the ~12ish green screws holding the upper panel in place. One is hidden under a sticker. Pop the panel off with more prying, as gently as you can but some force will be needed.
* After removing the glass, remove the ~12ish green screws holding the upper panel in place. One is hidden under a sticker. Pop the panel off with more prying, as gently as you can but some force will be needed.
* This is the end of disassembly, the test points are now exposed.
* This is the end of disassembly, the test points are now exposed.
* Solder as shown in diagram.
* Test connectivity between everything to make sure there's no shorts.
* Connect to your favorite UART adapter. It expects 1.8v, but I used [https://www.sparkfun.com/products/12731 this] adapter that only goes down to 3.3v, and it hasn't bricked yet.


[[File:Xiaomi_Willow_UART_locations.jpeg|thumb|Test point locations]]
[[File:Xiaomi_Willow_UART_locations.jpeg|thumb|Test point locations]]

Revision as of 09:15, 29 April 2020

Xiaomi Redmi Note 8T
Redmi Note 8T
Redmi Note 8T
Manufacturer Xiaomi
Name Redmi Note 8T
Codename xiaomi-willow
Released 2019
Hardware
Chipset Qualcomm SDM665 Snapdragon 665 (11 nm)
CPU Octa-core (4x2.0 GHz Kryo 260 Gold
4x1.8 GHz Kryo 260 Silver)
GPU Adreno 610
Display 1080 x 2340 IPS LCD
Storage 32GB, 64GB, 128GB
Memory 3GB, 4GB, 4GB
Architecture aarch64
Software
Android 9, MIUI 10
Android 9, MIUI 10
postmarketOS
no
4.14.117
4168.2
Device package device-xiaomi-willow
Kernel package linux-xiaomi-willow
Features
Works
Partial
Untested
Partial
Touchscreen
Works
Multimedia
3D Acceleration
Broken
Untested
Camera
Untested
Connectivity
WiFi
Broken
Bluetooth
Untested
GPS
Untested
Modem
Calls
Untested
SMS
Untested
Mobile data
Untested
Miscellaneous
Untested
Sensors
Untested

Contributors

Maintainer(s)

Users owning this device


Note

This device is quite similar to the Xiaomi Redmi Note 7 (xiaomi-lavender), and many of the issues were solved with steps from that device page, so if you're hacking on the 8T it's a good idea to read the xiaomi-lavender page closely.

How to enter flash mode

Unlocking the bootloader

As with any Xiaomi device, in order to unlock the bootloader you need to sign up for a Mi Account, register your device through the MIUI Settings app (requires a working SIM inserted, but only for a few moments), and wait a week. The official Xiaomi tool only runs on Windows, but XiaoMiTool V2 worked for me on Debian Linux. Be careful, it's a closed source jar!

Before you go further

You are strongly recommended to install TWRP and back up ALL partitions to a safe place! (you can adb pull the images from twrp)

Entering recovery

Hold Volume Up + Power until you see the recovery screen.

Entering fastboot

Hold Volume Down + Power until you see the fastboot screen.

Installation

  • Install pmbootstrap.
  • pmbootstrap -y zap; pmbootstrap init, choose xiaomi-willow as your device
    • firmware is currently needed for tianma touchscreen
    • rndis doesn't work, and weston is currently the only working display server, so pick weston for ui if you want to know if the flash worked
  • pmbootstrap install
  • Enter fastboot, plug USB into computer
  • pmbootstrap flasher flash_kernel
  • pmbootstrap flasher flash_rootfs
  • pmbootstrap flasher flash_vbmeta
  • Reboot, sometimes fastboot reboot works, otherwise hold down Power until it reboots to system.
  • Hopefully weston comes up with postmarketos-demos.

Getting a shell

RNDIS doesn't work yet, not sure why. Could be an easy fix for someone more experienced with Qualcomm USB drivers.

(Easy) USB-C to Ethernet adapter

If you have a USB-C to Ethernet adapter with drivers already compiled into mainline, this will be easy. I had an iTeknic IK-UC002 lying around, which has an RTL8152 inside, merged into mainline a while ago and already included the downstream Kconfig. device-xiaomi-willow includes an interfaces file so that eth0 is DHCPed at boot, and then avahi-daemon will advertise itself at hostname.local.

So if the phone is connected to your LAN at boot through the adapter, you should be able to ssh user@xiaomi-willow.local from your computer.

(Hard) UART

Necessary: reasonably fine soldering iron tip, steady hand Highly recommended: microscope, steadier hand

  • Disassemble the phone. Here's a decent video.
  • I spent way too much time heating up the rubber and trying to use a suction cup. The glue is quite strong, and after heating up the edges to unreasonable temperatures I still couldn't pull the glass off with a suction cup. The key is to heat up the bottom a bit (around 100-150C) and use an extremely thin piece of metal to slide in the bottom and tear the rubber a bit. Then you can keep heating the edges and work your way around the perimeter.
  • After removing the glass, remove the ~12ish green screws holding the upper panel in place. One is hidden under a sticker. Pop the panel off with more prying, as gently as you can but some force will be needed.
  • This is the end of disassembly, the test points are now exposed.
  • Solder as shown in diagram.
  • Test connectivity between everything to make sure there's no shorts.
  • Connect to your favorite UART adapter. It expects 1.8v, but I used this adapter that only goes down to 3.3v, and it hasn't bricked yet.
Test point locations
Only TX pin soldered
Blurry pic of TX and RX soldered

See also