Miyoo Mini Starter Guide

Last updated: 07JAN2023 (see Changelog for details)

This guide will show you everything you need to know about the Miyoo Mini — where to buy one, the best tools to get it set up, accessories, and how to install custom operating systems like Onion and MiniUI.

Buy one here: AliExpress | Amazon (faster shipping) | KeepRetro

Note that due to demand, availability has been an issue. The cheapest prices will be through the official Miyoo store on AliExpress, but you will need to check periodically to see when the device will be in stock. You can also try KeepRetro who will take your order and ship it when it is available, or you can pay a premium price on Amazon to get it more quickly. Here is a video with tips on how to buy a Miyoo Mini.

Table of Contents:

Recommended tools
Accessories and mods
Update to the April 2022 firmware
OnionOS installation
Add BIOS files
Add game files and images
Customize your themes
MiniUI installation
Custom boot logo

Changelog

Recommended tools

To install new firmware, I recommend starting from scratch with a new microSD card. You could use a 16GB card to save on costs and keep your game library trim (which will also result in faster navigation), or you could fill it up with the works. Personally, I use a 32GB card in mine, with only a few PS1 and Sega CD games taking up the majority of the space. Here are the cards I recommend:

16GB cards: 
SanDisk Ultra  
SanDisk Industrial

32GB cards:
Samsung Pro Endurance
SanDisk Extreme

64GB cards:
Samsung Pro Endurance
SanDisk Extreme

128GB cards:
SanDisk Extreme
Samsung EVO Select
Samsung Pro Endurance
SanDisk Ultra

The Miyoo Mini v2 comes with a cheap SD card reader, but I recommend a nicer one instead. This one from Anker has never done me wrong.

Accessories and mods

One of the great things about a popular device like the Miyoo Mini is that the community comes together to find all sorts of accessories and solutions to every little need. There are plenty of choices when it comes to custom buttons and stickers, 3D-printed grips, and more. The Miyoo Mini is approximately the same size as a deck of playing cards, so playing card cases are great alternative carriers for this device.

Cases:
Maze (synthetic) leather case
Custom leather case
Hardshell case (use coupon RETROGAMECORPS10)
Snap-on screen protector case

Other accessories:
Buttons and stickers
Magnetic charging dock
3D-printed grips

Update to the April 2022 firmware

In order to use the most recent versions of OnionOS, you must first update the Miyoo Mini base firmware to the April 2022 (or later) version. To check your firmware version, go to Setting > Device Info and verify the the “Version Number” is 202204190828 or “20221216XXXX” — if so, you are good to go to the next section. If it is something earlier (i.e. it starts with 202201… instead) then follow the firmware update instructions below.

• Save any important game files or your BIOS folder to your computer just in case.
• Go to the Miyoo website and download the latest image update, then unzip the file.
• In the unzipped folder, go to “The firmware” > miyoo283_fw.img and drag that file into the root of your Miyoo Mini SD card
• Go to “TF card” folder and drag the three subfolders (Emu, miyoo, and RetroArch) into the root of your card, and replace any existing files when prompted (this part is optional).
• Eject the SD card from your computer and plug it into the Miyoo Mini
• Plug the Mini into a wall charger, and be sure to use use a low-wattage wall plug. For best results, use a USB-A to USB-C cable, and a “smart” plug that can adjust wattage, or one of those cheap 5V/1A plugs that used to come with cell phones.
• The Miyoo Mini will automatically power on and run the update. Don’t touch the device at all!
• The device will restart and will then display a battery image and the charging screen. At this point you are done. Unplug the device from the cable and remove the SD card.
• Plug the SD card into your computer and delete the miyoo283_fw.img file before doing anything else.

Here is a fancy infographic (credit: PIXELSHIFT and TNGLIKER) that walks you through the process. Their process is a bit different, in that they move the “TF card” files to the SD card after the upgrade; either method works fine.

If you are having issues upgrading your device, or it gets caught in a loading screen while flashing the new firmware, follow the instructions provided in this Reddit comment.

PSA: new Miyoo Mini devices are showing up with “20221216XXXX” firmware on them and they are only compatible with OnionOS v4.0.4 and later. Be sure to use the latest OnionOS release.

OnionOS installation

Here are the installation instructions for Onion. For a full list of features, stop by their Features page. If you run into any issues, be sure to check out Onion’s comprehensive wiki page.

• Format your microSD card to FAT32 file system.
  • If using Windows, use the guiformat tool to format the card to FAT32. You can name it whatever you want.
  • If you have a Mac, “Erase” the disk using the Mac’s built-in Disk Utility app, with the format MS-DOS (FAT), name it whatever you want.
• Head over to the Onion GitHub Releases page and grab the latest release (it will be a zip file).
• Unzip the file, and place all of the contents into your SD card.
• Eject the SD card and place it in your Miyoo Mini. Start up the device and it will run the installer.

To update from a previous release of Onion, check out the Onion upgrade instructions from their wiki page.

Credit for Onion goes to their wonderful ragtag team of community contributors.

Add BIOS files

Once you have run the Onion Installer, you can now shut down the device, eject the microSD card, and add your files to it.

In the BIOS folder, add your BIOS file collection. You can simply copy/paste the files from your stock SD card, or add your own. On the stock SD card, you can find the BIOS files under RetroArch > .retroarch > System

You will need to be able to see hidden files in Windows or your Mac to see the .retroarch folder. Here is how to do that:

• Windows 10: Open File Explorer from the taskbar. Select View > Options > Change folder and search options. Select the View tab and, in Advanced settings, select Show hidden files, folders, and drives and OK.
• MacOS: Press CMD + SHIFT + . (period) to show/hide hidden files.

To see a recommended list of BIOS files to add, head over to the Onion wiki page to see their list of emulators and recommended BIOS files for each system. For most systems, BIOS are not required, but can enhance the playing experience (like adding the original boot logo when starting up a game). For systems like PS1, Sega CD, and TurboGrafx-CD, BIOS are a necessary component.

Add game files and images

In the Roms folder, add your game files into the corresponding subfolder. Some of the folders are named after their Japanese counterpart, like “FC” (Famicom) for NES, “MD” (Mega Drive”) for Sega Genesis, or “PCE” (PC-Engine) for TurboGrafx-16. For a full listing of each folder and the accepted file extensions, check out the Onion wiki page. You can also run a limited number of ports and third-party apps on the device, too.

When adding game files for systems that use the same RetroArch core file, you can create subfolders. For example, You could make Sega CD and Sega 32x subfolders inside of your Sega Genesis to clean up your front menu and streamline the navigation experience.

If you would like to add boxart to your games, here is more information.

For a list of hotkeys in Onion, check out this page. For more in-depth features and issues, check out their FAQ page.

Customize your themes

The Onion apps section has the ability to install your own themes, and you can also grab more from this massive themes repository. Moreover, you can adjust the themes to your liking, or create your own.

You can also adjust the music in the themes; for example, you could download this lo-res version of the Retro Game Corps theme song and add it to your theme of choice. In a fun twist, this theme was written by Jim Gray, one of the first Onion developers. Thanks to HyperPragmatist for editing the song down to work as a Miyoo Mini theme! To add your own track, rename the file to “bgm.mp3” and place it in the Themes > [name of theme] > sound folder on your SD card). Note that the tracks need to be 96kbps, 48khz, mono, and under 2 minutes to work as a Miyoo Mini theme.

MiniUI installation

MiniUI is a lightweight launcher that is focused on simplicity. As expected, the installation of MiniUI is simple. Note that the Miyoo Mini firmware upgrade is not required for MiniUI.

• Head over to the MiniUI GitHub page and download the latest release
• Inside the release will be a readme file, simply follow those instructions!
• If you would like to add the official “extra” systems, download the extras zip from the same releases page and follow the instructions inside the provided readme file
• If you would like to add community-driven “extra” pak systems, check out Tiduscrying’s repo.

Note that in my initial MiniUI video, I mentioned that some SNES games don’t play at full speed. One way to improve performance is to keep the games at Integer Scaling (“Native” in the options menu) which will improve performance. For example, Final Fantasy III (SNES) will play at full speed without frameskip when at Native resolution.

To update MiniUI, download the latest release (base version), unzip the file, and move the miyoo folder into your SD card. It will take care of the rest upon your next bootup.

Credit for MiniUI goes to the always-prolific Shaun Inman.

Custom boot logo

Note that as this time, if you are running the 20221216XXXX firmware on this Miyoo Mini, this process will brick your device. This is only recommended for devices running firmware older than 20221216XXXX.

If you would like to use (or create) a custom boot logo for your Miyoo Mini, you can follow the instructions in the video above. This can be used with any firmware or operating system. Here are all the pertinent links that you’ll need to get set up:

LogoTweak app
Retro Game Corps boot logos (right-click and select “Save As…”)
Additional boot logos from artist JDewitz (right-click and select “Save As…”)
Additional boot logos from PaynefullyCreated (right-click and select “Save As…”)

If you happen to brick your device in the process (I haven’t heard of a single instance with any firmware except for those running 20221216XXXX, but it’s still theoretically possible on the older firmwares), here are instructions on how to recover your device. Here is another set of instructions to recover the device.

Note that the disappearing boot logo images in MiniUI (as shown in the video above) have now been fixed by the LogoTweak developer, so it will work great in both OnionOS or MiniUI.

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Changelog

07JAN2023
– updated logo tweak section to warn users about potentially bricking their device if it is running 20221216XXXX firmware

01JAN2023
– updated warning to coincide with OnionOS v4.0.4 release which fixes the 20221216XXXX firmware issue

31DEC2022
– added warning about “20221216XXXX” firmwares

28SEP2022
– added Onion v4 installation guide video
– streamlined the accessories section

26SEP2022
– updated Onion install instructions
– separated the firmware update section
– added MiniUI update instructions

15AUG2022
– added custom theme music and custom boot logo instructions

26JUL2022
– updated links to OnionOS repo and FAQ fork

19JUN2022
– added additional complementary videos

15MAY2022
– published guide