OnionOS on the Miyoo Mini Plus

Miyoo Mini Plus: installing OnionOS and adding ROMs

Step-by-step guide for installing OnionOS and adding games to your retro handheld

Want to install OnionOS on your Miyoo Mini Plus and then add games yourself? In this guide I’ll show you step by step how to do that.

We’ll start with OnionOS and then we’ll put ROMs onto the SD card. Already got OnionOS installed? Then you can just skip the first part.

Charging: No fast chargers, please!

Tip: Preferably charge your Miyoo Mini Plus with the included cable and a PC or another regular 5V USB port. Use a suitable 5V charger. I’d leave modern fast chargers alone, just to be safe, with our beloved retro gadgets!

Installing OnionOS on your Miyoo Mini Plus

OnionOS is an alternative operating system for the Miyoo Mini and Miyoo Mini Plus. It gives you a nice interface, lots of emulators and all kinds of extra features, like save states, themes and the GameSwitcher that lets you switch between games quickly.

And the nice thing is that you can just install it yourself.

Level 1: Check your firmware

Before we install OnionOS, we first need to check which firmware is on your Miyoo.

1. Turn on your Miyoo Mini Plus.

2. Go to Settings > Device Info > Version.

3. Check which firmware version you have.

For the Miyoo Mini Plus you need at least firmware version 20230505. Newer firmware versions also work, of course.

Using the original Miyoo Mini? Then you need at least the suitable firmware from April 2022. Note: certain old firmware versions have issues and require a special patch.

Got older firmware? Then first take a look at the official OnionOS firmware guide.

Note: Updating the firmware is something different from installing OnionOS. A firmware update carries risks. For that, really follow the official instructions.

Level 2: Prepare the SD card

Preparation:

1. Get a good microSD card. I personally recommend a card from SanDisk or Samsung, for example.

2. Put the SD card into your computer using an SD card adapter.

3. Make a backup if there are already games, saves or other files on it.

4. Format the SD card to FAT32.

Note: FAT32 is not the same as exFAT. OnionOS really needs FAT32.

Windows:

Got an SD card larger than 32GB? Then use, for example, Rufus.

1. Select your SD card.

2. Set Boot Selection to Non bootable.

3. Choose MBR as partition scheme.

4. Select Large FAT32 as file system.

5. Click Start.

Mac:

On a Mac you can just use Disk Utility.

1. Open Disk Utility.

2. Select your SD card, preferably the top device.

3. Click Erase.

4. Choose MS-DOS (FAT) as the format.

5. Choose Master Boot Record as the scheme.

6. Click Erase.

And your SD card is ready.

Level 3: Download OnionOS

Now we’re going to download OnionOS.

1. Go to the official OnionOS GitHub.

2. Find the latest stable version of OnionOS.

3. Download the installation file, for example Onion-v4.x.x.zip.

4. Unzip the ZIP file on your computer.

You’ll now see a number of folders. For the current installation these are:

• .tmp_update

• BIOS

• Media

• miyoo

• miyoo354

• RetroArch

• Themes

Important: The folder .tmp_update is a hidden folder. You need to copy that too!

On a Mac you can make hidden folders visible with Command + Shift + . in Finder.

Level 4: Put OnionOS on the SD card

Now it gets easy.

1. Open the extracted OnionOS folder.

2. Select all seven folders.

3. Copy these to the root of your SD card.

4. Wait until all files have been copied.

5. Safely remove the SD card from your computer.

6. Put the SD card back into your Miyoo Mini Plus.

7. Turn the device on.

OnionOS will now start installing automatically.

When the installation is done, you’ll first get a short introduction and then see the Package Manager.

Here you can choose which emulators and apps you want to install. Select the systems you want to use and press the Start button twice to confirm your choices.

Then press A when the installation is complete. Your Miyoo Mini Plus will restart.

OnionOS is now installed!

By the way, don’t remove the folder .tmp_update from your SD card. Despite the name, this is part of OnionOS.

Level 1: Put the SD card in your PC

Now OnionOS is installed, we’re going to add games.

Preparation:

1. Carefully remove the SD card from your Miyoo Mini Plus.

2. Use an SD card adapter if your PC doesn’t have a built-in card reader.

3. Insert the SD card into your computer’s card reader.

4. Open the SD card via File Explorer.

Level 2: Download and prepare ROMs

Getting ROMs:

Download ROMs only from legal and reliable sources. Take a look at Itch.io. There you’ll find cool new homebrew games, many of which you can download for free. You can also choose to support the developers by making a donation.

Of course you can also use your own legally obtained ROM files.

Unzipping ROMs:

ROMs are often compressed in a ZIP file. Some emulators within OnionOS can work directly with ZIP files, but that isn’t the case for every system.

Need to unzip a ROM? You can do that with a program like 7-Zip:

1. Right-click the ZIP file.

2. Choose 7-Zip > Uitpakken naar….

3. Select a destination for the extracted files.

On a Mac you can usually open most ZIP files by double-clicking them.

Level 3: Put ROMs on the SD card

Organising files:

1. Open the Roms folder on your SD card.

2. Copy the ROM files to the correct subfolders:

   • GB → for Game Boy ROMs

   • GBC → for Game Boy Color ROMs

   • GBA → for Game Boy Advance ROMs

   • FC → for NES ROMs

   • SFC → for SNES ROMs

   • MD → for Sega Mega Drive ROMs

   • PS → for PlayStation 1 ROMs

   • And so on for other systems!

3. Put the SD card back into your Miyoo Mini Plus.

Some systems also need BIOS files. Put these in the BIOS folder on your SD card. Which files you need exactly depends on the emulator.

You can find the correct folder names and BIOS requirements in the official OnionOS emulator list.

Ready to go!

Don’t see any games in the menu? Follow these steps:

1. Turn on your Miyoo Mini Plus.

2. Go to Games in the main menu.

3. Press the Select button.

4. Choose Refresh all roms to refresh the ROM list.

Your games should now be visible!

If that doesn’t work…

Sometimes ROMs aren’t recognised because the list hasn’t been updated or because they’re in the wrong folder.

Then check the following:

1. Is the ROM in the correct folder?

2. Is the file format supported by the emulator?

3. Have you activated the correct system in the Package Manager?

4. Have you refreshed the ROM list again?

Using a Mac? Then hidden ._ files may also end up on your SD card. You can remove them via Apps > Tweaks > Tools > Remove OSX files.

Activating extra systems in OnionOS

Want to add even more retro consoles? That’s easy in OnionOS:

1. Go to Apps > Package Manager on your Miyoo.

2. Turn on the systems you want.

3. Press the Start button twice to save the settings.

Your SD card will now get extra folders in the Roms folder! That means you can play even more classic games.

Updating OnionOS later

Updates for OnionOS are released regularly.

Got a Miyoo Mini Plus with wifi? Then you can also update OnionOS via the OTA Update app.

You can also install updates manually. For safety, first make a backup of your SD card, especially your saves and games.

You can find the official instructions on the OnionOS GitHub and in the update guide.

Final step…

Ring your neighbours’ doorbells and tell them about this amazing guide!!

Just kidding, don’t do that… but..

If this post helped you, I’d hugely appreciate it if you shared it with friends or acquaintances.

For cool reviews on retro handhelds, have a look at our friends at RetroReady.

And if you’re still looking for a Brick, MM+ or another retro device, be sure to check out my webshop RetroGear.

-XXX-

Jorne