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Wiki > Main > FiioM3K

FiiO M3K

Hardware summary

Component Model Notes
SoC X1000E 1.0GHz MIPS XBurst with 64MB of SIP LPDDR RAM
PMU AXP192 I2C PMU, driver is AXP173?
Backlight driver SGM3122 simple PWM LED driver
Touch controller FT6236U I2C
LCD controller likely ST7789S educated guess from Fiio's M3K kernel source
Microphone MSM42A3722H9KR plain MEMS analog mic
Battery 413372 2-wire with built-in basic protection circuit, 1100mAh

Hardware notes

  • Touchpad backlight
    • Driven by an S8050 (J3Y) and presumably a GPIO.
    • TODO: Which GPIO??
  • About the LCD
  • Audio Codec Notes
    • in-kernel driver is a real mess, but at least we have source code!
    • Powerup pin controlled by GPIO A16, requires a magic ioctl(!) to /dev/ak4376 to toggle
    • Most mixer controls are no-ops, meant for different HW. Only DACL/DACR Playback volume and "Low Mode Switch" are connected to HW. DAC filter also not hooked up.

Internal images

PCB images:

PCB_front_s.png PCB_back_s.png

Closeup of the PWM LED controller and the I2S DAC:

SGM3122_s.png AK4376A_s.png

Screen assembly closeup:

TODO: transcribe silkscreen text


TODO: transcribe silkscreen text and pinout



All datasheet links were archived versions whenever possible.

Disassembly instructions

Disclaimer: everything you do is at your own risk and I cannot be held responsible if you damage your device or overheat the battery and it catches on fire.

Please don't attempt it unless you can afford to damage the device, this is for your reference only. There are no real benefits of disassembling the device (internal photos are already available from me and all the important chips have been identified) unless you want to access the native UART port (which doesn't have an interactive boot console that you can interrupt btw, the loader is not u-boot), and you'll need some E6000 adhesive to glue the screen back if you want to put it together again.

Tools required:
  • Hair dryer
  • LCD screen repair plier tool with removable suction cups
  • E6000 adhesive
  • Precision Philips screwdrivers
  • Plastic pry tool (the triangular type)
  • A thin plastic card
  • Xacto knife
  • Kapton tape

  1. Unscrew a suction cup from your plier tool, firmly adhere it to the upper back side of the device with the E6000 glue, let it sit for at least 14h. Be generous with the glue, you'll be able to cleanly remove them later before they harden completely. This is necessary because the aluminum back doesn't play nice with the suction cup, it slips off before you can exert enough force onto the front glass.
  2. Heat up the front of the device until the aluminum frame is very hot to the touch. Immediately screw the glued suction cup back onto the plier tool, and you should be able to get enough grip to pull the screen off now. You must pull it apart from the LCD side (not the touch controls side) to avoid damaging the ribbon cables.
  3. Detach the two ribbon cable connectors and remove the screen assembly. Beware that the touch controller ribbon cable has a sticky back, carefully peel it off the board with a tweezer. Hit it with a hair dryer if it's hard to remove, that'll hopefully soften the adhesive.
  4. Take your triangular pry tool, use it to push up & warp the upper panel from the inside of the device, there's an aluminum overlay that you'll hopefully be able to separate with your xacto knife (the key here is to cut away the adhesive instead of prying). There will be two screws hidden under that overlay, remove them and you'll be able to side the entire inner tray out from the bottom side.
  5. Peel off the black insulation tape on the board to reveal some test points, including UART. Put on some Kapton tape before you attach the screen to prevent the metal bracket from shorting anything out.
  6. Remove the 6 screws from the plastic tray (one screw is smaller than the rest), and you can take the board out.
  7. Heat up the board again from the front side and use a thin plastic card to slowly separate the battery from the board. The PCB bends pretty easily so be careful NOT to bend it in the process, I find gripping on the PCB on the long sides can reduce bending. After you detach and desolder the battery, the disassembly is now complete.

I Attachment Action Size Date Who Comment
AK4376A_s.pngpng AK4376A_s.png manage 2611.1 K 07 Jul 2020 - 01:33 EdwardBiryukov  
PCB_back_s.pngpng PCB_back_s.png manage 4760.8 K 07 Jul 2020 - 01:32 EdwardBiryukov PCB back
PCB_front_s.pngpng PCB_front_s.png manage 4261.3 K 07 Jul 2020 - 01:32 EdwardBiryukov PCB front
SGM3122_s.pngpng SGM3122_s.png manage 2744.7 K 07 Jul 2020 - 01:33 EdwardBiryukov  
m3k_alsa.txttxt m3k_alsa.txt manage 3.0 K 15 Oct 2020 - 11:55 SolomonPeachy Exported ALSA Mixer controls
screen_assembly_overview_s.pngpng screen_assembly_overview_s.png manage 3248.6 K 07 Jul 2020 - 01:34 EdwardBiryukov  
touch_controller_closeup_s.pngpng touch_controller_closeup_s.png manage 4079.7 K 07 Jul 2020 - 01:34 EdwardBiryukov  
r3 - 15 Oct 2020 - 12:22:46 - SolomonPeachy

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