Bootleg Radio

A lo-fi bootleg tribute to Music Thing Modular's Radio Music - not a replacement, but a cheaper, grubbier cousin. Named for the 538 AM pirate broadcasters off the Dutch coast (and the Botlek, the grimy Rotterdam docklands where sub- and pirate culture ran thick), it deliberately keeps the hiss and the seams. Load a USB stick with WAV files, plug it into the Computer's front USB-C jack, and tune through them like radio stations. For a ready-made start, the [Radio Music Suggested Audio](https://www.musicthing.co.uk/Radio_Music_Suggested_Audio/) page is a great set of loops and samples to load onto the stick and try the card. The Main knob and CV in 1 pick the station, the X knob and CV in 2 set the tape speed, the Y knob and Audio in 1 set the loop start, and Audio in 2 sets the loop length. Each station loops over its window; the switch retriggers, selects banks, or (held) changes the tune mode.<br><br>

Files are grouped into banks: the root directory is bank 0, and each subdirectory that holds WAV files is another bank (up to 32). Hold the switch up and turn Main to change bank; a new bank starts at its first station. The root is always bank 0 even if it holds no WAVs, in which case the card starts silent until you pick a folder. Banks and the stations within them are natural-sorted (case-insensitive, digits compared as numbers), so the order matches Finder; a bank holds up to 64 stations.<br><br>

Files must be uncompressed 16-bit PCM, mono or stereo, at any sample rate up to 192kHz; they are resampled to 48kHz on the fly. This is a hacker's sampler rather than a pristine one: the DAC is 12-bit and the resampling is simple linear interpolation, which is part of the character.<br><br>

Tuning can be a "synchronised jump" - the new file picks up at the same proportional position where the old one stopped - so a slow sweep through the stick keeps its place instead of restarting everything at the beginning. This is the default "Sync" mode; holding switch-down toggles to "Loop" mode, where a new station starts at its loop start point. A deliberate retrigger, or reaching the loop end, restarts from the live loop start point.<br><br>

Needs a Rev 1.1 or later Computer (the revision with USB host support), and nothing else may be in the front USB socket, because the Computer has to act as a USB host.

Copy the UF2 onto the Computer's program card (RP2040 bootloader drive).