Miyoo Mini v2 Guide

Last updated: 15AUG2022 (see Changelog for details)

There is a new version of the Miyoo Mini available, and so in this video we’ll take a deep-dive review of the differences between the v1 and v2 versions of this tiny little device. Additionally, let’s set up new custom firmware using the latest versions of OnionOS and MiniUI.

If you are looking for the v1 Miyoo Mini Onion guide, you can find it here. Note that the v1 guide is now outdated.

Credit for Onion goes to their wonderful ragtag team of community contributors. They do not have a direct donation set up for the project, but if you are feeling generous, they requested you make a donation with the Mutual Aid Disaster Relief fund in their honor. Credit for MiniUI goes to the always-prolific Shaun Inman.

Buy the Miyoo Mini v2 here

Table of Contents:

Recommended tools
OnionOS installation
Add BIOS files
Add game files and images
Customize your theme music
MiniUI installation
Custom boot logo


Recommended tools

128GB SanDisk Ultra and Samsung EVO Select microSD cards

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 an SD card reader, but I recommend a nicer one instead. This one from Anker has never done me wrong.

The Miyoo Mini is approximately the same size as a deck of playing card, so playing card cases are great alternative carriers for this device. You could try out the (synthetic) leather cases found in the video below, or even go super cheap with some $3 plastic cases.

Also in the video above I discuss some of the color options available, as well as how to fix light bleed on the transparent models if that’s something you’re interested in trying.

OnionOS installation

In order to use the most recent version of OnionOS, you must first update the Miyoo Mini base firmware to the April 2022 version.

  • 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.

click image for full-scale resolution

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.

Now let’s actually install Onion.

  • 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 you should have a single folder, and inside will be a subfolder named “.tmp_update”. Drag this folder into your freshly-formatted FAT32 microSD card. If you don’t see the folder, follow the instructions in the next section about enabling hidden files.
  • Eject the SD card and place it in your Miyoo Mini. Start up the device and it will run the installer.

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. For best results, use the psxonpsp660.bin BIOS file for PS1.

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.

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.

Customize your theme music

The Onion apps section has the ability to install your own themes. Moreover, you can adjust the themes to your liking. 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.

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. 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, but it’s still theoretically possible), 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.


– added custom theme music and custom boot logo instructions

– updated links to OnionOS repo and FAQ fork

– added additional complementary videos

– published guide

19 thoughts on “Miyoo Mini v2 Guide

  1. I just ordered a V1 and I was wondering if this guide is applicable to that or just the V2? I want to make sure to get Onion on there and want to get everything done right!


    1. Yes, this will also work with the V1 model, as long as you’ve updated the base firmware to the April 19 release.


      1. Appreciate it! I’m so spoiled with US shipping. The wait is killer for AliExpress.


  2. My V2 justed arrived, but without any sd-card. I found a download-link to the image, but it’s not recognized by the miyoo mini. It says “unmounted”. I flashed the zip-file as an image to the sd-card. Any ideas how I can get my device to work?


  3. Thanks for making this update video, I kinda had to put my Mini on the back burner for a little bit because I wasn’t sure how to get Onion installed. Works great now though!


  4. Now the firmware upgrade comes with two TF Card folders and it is not clear which one should go on the sd card.


  5. Hi Russ,
    great video, made me instantly order a V2 version, although I also have the V1. It arrived (finally!) today and I tried to copy over my save files from V1 to V2. So here’s what I did:
    (Note: I have Onion OS installed on both devices, also the same emulators)
    – Copied the roms to their exact folders from device 1 to device 2, maintaining their file names
    – Copied the \states and the \saves folders into their respective RetroArch folders
    – Started up a game that I had previously save files for
    But nothing happens, the game starts from the beginning, as if there never was a save before. Manually loading a save file through RetroArch doesn’t work either.
    So, HELP please! How can I get my save files to work on the V2 device? Thanks!


  6. Hey Russ,

    I installed the OnionOS v3.11.2 on my Miyoo Mini v2. The problem is that on the Miyoo Mini I can see all the hidden files when navigating through the interface. For example in NES section I can see the ._* versions of the games I added to the FT card so that the game count shows the double of actual games. And those hidden files with the names of actual games won’t even open.

    I would appreciate your advice,

    Thank you in advance


  7. Onion OS doesnt load some roms after following this guide.
    GBA, FC, and SFC roms bring up a loading text then returns back to the Onion OS rom list. But if I Apps>RetroArch>Load Content>Navigate to ROM folder>Run rom with any core it works. I have verified the naming/path/capitalization is correct.

    My GB and PS Roms work from the OnionOS Menu

    I installed Onion OS on a fresh SD card and just copied the roms from the Stock SD over.


    1. I had better luck running PS1 games in BIN/CUE format. Probably, ISO format, too. PBP originally is the format that PSP runs for when emulating PS1 titles natively.


  8. Today I got my Miyoo Mini V2 (Firmware is already 20220419 ) and wanted to install the newest onion firmware. I formated a new sandisk 32gb microsd card and copied the “.tmp_update file” to the root of the sdcard and put it back to the miyoo mini. After powering on the device the onion installation screen appeared but stuck in showing “Installing cores” for hours. Nothing more happened 😦
    Afters 2 hours I disconnected the battery and tried to boot with the old microsd with original firmware.
    Luckily this worked 😉
    I tried with another sdcard, but same problem 😦
    Any idea for help?
    How long is the normal process when installing onion, How long do I have to wait till process is ready? Minutes or hours?


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