Consumer radios, CD players, and car stereos often have a USB port, to play mp3's from a FAT32-formatted USB stick. However, some models don't just read files, they also corrupt files. How can such corruption be avoided or mitigated?
Examples of such misbehaving devices include my own Teac CD-P650, which on some USB sticks reproducibly leaves many directories empty (the missing mp3's move to /FOUND.000, after a Windows
chkdsk), and a Duronic RCD99W boombox (from a forum post, lacking any details).
Some thumbdrives survive unscathed. On other thumbdrives, which folders get erased has no pattern. They aren't the largest ones (by number of bytes or minutes per file or per folder, or number of folders per file (max 99)), nor are they the first in alphabetical order.
Write-protecting files doesn't solve the problem: directories still get emptied. (Anyways, in FAT32 that's iffy: How to write protect a USB key?). Mechanically write-protecting the entire USB stick yields the same result. In both cases, audio still plays, so the player isn't upset about this hypothetical thwarting of writing temporary data. (Few USB sticks nowadays have a mechanical switch; I faked that with a write-protected SD card in a USB card reader.)
How might one even troubleshoot this? Where to begin? Disassemble the device to learn its USB chipset? What if the chipset is just a microcontroller bit-banging two pins?