Some notes on the FiiO M3K Mini HiFi. As of July 2021, the M3k is available from amazon.com . A build of rockbox for the device exists, and works just great!

• rockbox emulators
• M3k on Amazon Japan
• details from vendor
• My blog entry on the "Bad apple" port to the M3K, the code, Rockbox forum

• OpenSource pieces
• support for many codecs, like ogg vorbis, Amiga mod and sid files
• _really_ configurable: multiple bookmarks per file can be set, fading from one file into the next and much more
• There are plugins for playing doom, quake, duke3d
• A One-Time password client
• emulation
  • gameboy/gameboy color emulator are buildin:place files with .gb or .gbc extension
  • NES emulation project exists
• If you need something, you can create it!

This is the native port, recommended nowadays.

• link to the port
• Install instructions, echoing here:
  • fetch jztool and bootloader.m3k
  • create a vfat filesystem on the card, copy bootloader.m3k to the card, unzip a rockbox release to the card (.rockbox directory)
  • Turn off the M3K, keep volume-down pressed while connecting to the Linux system, screen stays dark but lights at the touch fields light up
  • ./jztool fiiom3k load bootloader.m3k
  • Take a backup of the current bootloader, install the new one. From now on, the menu can be reached by holing volume-up while powering on the M3K.
  • Fetch a daily build for the FiiO M3K from here, unzip it into the root-directory of your microsd-card. It creates a .rockbox directory. Careful, there seem to be also “bad builds”, so by chance you hit one of these. For example, 2021-10-19 does not boot for me.
  • Just start up the M3K, it will boot Rockbox from the directory.
• The fast forward/rewind issues from the non-native port are gone.

This was the first “port”, rockbox more running in userspace as alternative to the native firmware. On each start, one has to select “rockbox”. The native port is recommended nowadays.

• forum link with details
• rockbox 1.4.3 firmware for the M3k
• update instructions
• usage notes for rockbox 1.4.3 on M3k
  • fast forward/rewind do not work in the default config, just a 'flickering' is seen. To fix this, go into “Playback Settings > Fast Forward / Rewind > FF/RW Accel” and change it to 'Very fast', then long pressing to fastforward/rewind works.
  • press the on/off button for 2 seconds to lock the device, and again to unlock it
  • creating bookmarks:
    • ensure these settings are in place
      • Menu→Settings→General→Bookmarks→On Stop→Yes
      • Menu→Settings→General→Bookmarks→Load Last→Ask
      • Menu→Settings→General→Bookmarks→Recent→Unique Only
    • Then, to create a bookmark, press the 'select' button for 2 seconds, that's the lowest button on the left side.

• https://www.rockbox.org/wiki/FiioM3K
• https://www.rockbox.org/wiki/HowtoWritePlugins
• https://www.rockbox.org/wiki/DevelopmentGuide
• https://www.rockbox.org/wiki/CrossCompiler

# Fedora34
sudo dnf install gmp-devel git
git clone git://git.rockbox.org/rockbox
cd rockbox/tools

# This should now build the crosscompiler for us
vi rockboxdev.sh
### I customized the path, to not build into /usr/local
./rockboxdev.sh

# At this point I needed to customize the PATH to point at the compiler:
export PATH="/home/chris/Downloads/rockbox/rockboxbin/bin:$PATH"

# Do a build
mkdir build
cd build
../tools/configure
make -j
make zip
# This should leave a zipfile which we can deploy as .rockbox
# to the sdcard and start the M3K!
cd ..

# Do a build of the simulator
mkdir buildsim
cd buildsim
../tools/configure
make -j
make fullinstall
./rockboxui

• https://blog.fluxcoil.net/posts/2021/08/rockbox-badapple-m3k/ – article
• https://github.com/christianhorn/badapple-lua – repo
• https://github.com/TT-392/Pinetime-bad-apple-video-processor – a Bad apple @pinetime project