Teardown: MPF1870 mp3 player

MP3 player with color LCD, 1 GB Flash memory, powered by LiIon cell.

 SoC: Action ATJ2097W, it was easy to find its datasheet and application diagrams. Key features:

  • 24 bit DSP (72 MIPS) - Motorola 56k compatible?
  • 8 bit MCU compatible with Z80
  • supports up to 3 NAND chips, up to 4GB each
  • external I2S DAC interface
  • supporting 1xAA, 1xAAA, 2xAA,2xAAA and Li-Lon
  • USB 2.0 high speed, mass storage device interface
  • delta-sigma DAC and ADC (for radio/microphone)
  • external 8080-series LCM driver interface(STN / Color STN) 
  • MMC/SD interface, up to 1 MB/s
  • built-in Li-lion charging management 
  • headphone driver, 2 x 11 mW @ 16 ohm
  • 120 kB SRAM, 50 kB ROM
Supply current: Ivdd = 21 mA typ with MCU @ 24 MHz, DSP @ 36 MIPS.
Interesting thing is that are four chip versions distinguished by last letter in symbol. They differ by RoHS compatibility and MP3 royalties inclusion. ATJ2097W version has no MP3 royalties included and is not RoHS compatible.
 NAND: Samsung K9K8G08U0A

 FM radio module with SP3767HN (TEA5767 clone)

Transfer speed is quite decent:
Since this player was in pretty good shape (only battery was missing) I was planning to give it to my brother, but I gave up. First reason: cell from Philips SA3113 didn't fit inside (too thick). Second reason: this is really poor player - I'm not suprised that it was abandoned by previous user. See the video:

Few remarks after 10 minutes of usage, I suppose this is just the tip of iceberg:
  • very dark display; brightness regulation in settings seems not to work; I wouldn't mind low resolution, but some fonts look awful
  • really sluggish operation
  • user interface for player is very unefficient - large ugly bitmap but only two files are visible at once
  • irritating in my opinion volume fading when switching between player tracks
  • record button switches to recording mode from almost any state and is quite easy to activate by accident
  • Polish translation is unusable; even with English language few menu positions in settings have cryptic names (DarkMode - brightness regulation, but not working?, CATOON - no idea, seems to have no effect?)
  • animation flickering, visible also when tuning radio
Radio is unusable. Even with strong stations it generates "digital" noises with regular frequency. I saw this issue with original TEA5767 when communicating via I2C, but it was not noticeable with strong stations. It could also be suppressed just by stopping communication when it was needed - I would prefer clear sound than having signal strength (not present here) or stereo indicator. Another problem: mono/stereo switch is not present in settings.

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