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Created May 31, 2026 14:55
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Blaustahl Storage Device — Quick-Start Guide
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blaustahl-guide.md

Blaustahl Storage Device — Quick-Start Guide

The Blaustahl is a tiny USB text dongle — not a disk drive. It holds about 8 KB (four 80×24 pages) of text in ultra-durable FRAM, and you read and write it through a built-in editor over a USB serial connection.

It will not appear as a drive in Finder, File Explorer, or lsblk — that's normal and by design. No drivers are needed on any modern OS (it uses the standard USB-CDC serial class).

Step 1 — Plug it in and find its serial port

OS Appears as How to find it
Linux /dev/ttyACM0 ls /dev/ttyACM*
macOS /dev/cu.usbmodem… ls /dev/cu.usbmodem*
Windows COMx Device Manager → Ports (COM & LPT) → look for "USB Serial Device (COMx)"

Step 2 — Open it in a serial terminal

Linux / macOS — use tio (simplest) or screen:

tio /dev/ttyACM0           # Linux
tio /dev/cu.usbmodem*      # macOS
# or, if you prefer screen:
screen /dev/ttyACM0

Install the tool if needed: sudo dnf install tio (Fedora) · brew install tio (macOS).

Windows — open PuTTY or Tera Term and set:

  • Connection type: Serial
  • Serial line / port: your COMx
  • Speed: any value (e.g. 115200) — baud rate is ignored over USB-CDC

Step 3 — Read and write your text

  • Your stored text appears in the editor right away.
  • Arrow keys move the cursor across the four pages.
  • The editor opens read-only. Press CTRL-W to toggle write mode, type or edit your text, then press CTRL-W again to return to read-only.
  • Edits are written straight to FRAM — they persist automatically; there is no separate "save" step.

Exit the terminal cleanly:

  • tio — Ctrl-T, then Q
  • screen — Ctrl-A, then K, confirm with y
  • PuTTY / Tera Term — just close the window

If it doesn't show up

  • No drive icon? Expected — it's a serial port, not mass storage. Don't look in Finder / File Explorer / lsblk; find the serial port from Step 1 instead.
  • No serial port at all? Unplug and replug it, ideally directly into a motherboard or laptop port rather than through a hub or dock. It occasionally enumerates without configuring itself; a replug clears that.
  • Linux "permission denied"? Add yourself to the dialout group once: sudo usermod -aG dialout $USER, then log out and back in.
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