Files
tinyusb/examples/device/cdc_msc
hathach 4b1c8d16f7 docs: add build-doc tooling and a README for every example
Documentation tooling:
- Add the `build-doc` skill and `tools/build_doc.py` wrapper for local
  Sphinx builds (clean / -W / open).
- Enable Markdown (MyST) in conf.py and auto-collect
  examples/{device,host,dual}/*/README.md into a 3-level Examples nav
  (Examples > Device/Host/Dual > example), noting each page's source
  location and normalizing headings to a single H1.
- Remove the stale `.claude/commands/build-doc.md`; point the AGENTS.md
  Documentation section at the skill.

Example docs:
- Add a README.md for every device/host/dual example: what it does, USB
  interface table, notable tusb_config.h settings, generic CMake + Make
  build steps, and how to try it.
- Fold each *_freertos variant into its base README, noting the FreeRTOS
  source path and any RTOS-specific behavior.

Generated docs/examples/ output is git-ignored. Builds clean with
`sphinx-build -W`.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-29 10:16:25 +07:00
..
2026-04-22 11:53:02 +07:00
2025-02-09 00:25:38 +01:00
2025-10-14 17:53:55 +07:00
2024-06-21 18:50:44 +07:00

CDC + MSC

A composite USB device that exposes two interfaces at once:

  • CDC — a virtual serial port (/dev/ttyACMx, or a COM port on Windows) that echoes back everything it receives.
  • MSC — a small mass-storage disk that mounts as a removable drive.

This is the canonical TinyUSB example for a multi-interface (composite) device.

What it does

  • CDC: reads incoming data and echoes it straight back. Pressing the on-board button sends a serial-state (UART) notification to the host.
  • MSC: presents an 8 KB FAT12 RAM disk (16 × 512-byte blocks — the smallest size Windows will mount) labelled TinyUSB MSC, containing a single README.TXT. The disk lives in RAM, so changes are not persistent.
  • LED shows bus state: 250 ms blink = not mounted, 1000 ms = mounted, 2500 ms = suspended.

USB Descriptors

Interface Class driver
01 CDC (virtual serial)
2 MSC (mass storage)

Configuration

Notable tusb_config.h settings:

#define CFG_TUD_CDC              1
#define CFG_TUD_MSC              1
#define CFG_TUD_CDC_RX_BUFSIZE   (TUD_OPT_HIGH_SPEED ? 512 : 64)
#define CFG_TUD_CDC_TX_BUFSIZE   (TUD_OPT_HIGH_SPEED ? 512 : 64)
#define CFG_TUD_MSC_EP_BUFSIZE   512

Building

CMake:

mkdir build && cd build
cmake -DBOARD=raspberry_pi_pico ..
cmake --build .

Make:

make BOARD=raspberry_pi_pico all

FreeRTOS variant

A FreeRTOS build is in examples/device/cdc_msc_freertos — identical CDC + MSC behavior, with the device, CDC, and LED-blink work split across FreeRTOS tasks.

Try it

  • Serial: open the CDC port (screen /dev/ttyACM0, PuTTY, …) and type — characters are echoed back.
  • Storage: a small TinyUSB MSC drive appears; open README.TXT to confirm it mounted.