https://github.com/flight/pi-pico-wav-c
https://github.com/flight/pi-pico-wav-c
Last synced: 5 months ago
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- Host: GitHub
- URL: https://github.com/flight/pi-pico-wav-c
- Owner: Flight
- Created: 2025-12-08T21:07:03.000Z (7 months ago)
- Default Branch: main
- Last Pushed: 2025-12-27T12:05:14.000Z (6 months ago)
- Last Synced: 2025-12-29T06:38:45.450Z (6 months ago)
- Language: C
- Size: 2.62 MB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# Pico WAV Player (PWM + DMA)
Plays an embedded WAV file out of the RP2040/RP2350 PWM pin (`GPIO0`) using a simple RC filter + speaker. Samples are streamed via DMA paced by a second PWM slice, keeping the CPU mostly idle during playback.
## Build
- Configure once: `cmake -S . -B build`
- Build: `ninja -C build`
- Output UF2: `build/pico-wav-c.uf2`
## Flash to Pico
- Hold BOOTSEL on the Pico and plug in USB; a drive named RPI-RP2 appears.
- Copy `build/pico-wav-c.uf2` to that drive (drag/drop or `cp`).
- The Pico reboots and begins playing immediately.
## Wiring
- Connect `GPIO0` through an RC filter (e.g., 10 kΩ + 0.1 µF) into your amplifier/speaker input.
- Share ground between Pico and amplifier.
- The PWM slice used for DMA pacing does not require an extra pin.
## Configuration
- Default audio pin is `GPIO0` (`AUDIO_PIN` in `pico-wav-c.c`). Change it if needed and reflash.
## Converting your own WAV
- The player supports PCM WAV only (no compression), 8- or 16-bit, mono or stereo. Stereo is downmixed by channel stride; sample rate is played as-is.
- Recommended: convert to mono 8-bit unsigned PCM to match the PWM wrap (0–255).
- Example with ffmpeg: `ffmpeg -i in.wav -ac 1 -ar 16000 -sample_fmt u8 sound.wav`
- Convert the WAV into a C header:
- `xxd -i sound.wav > wav_data.h`
- Ensure the header keeps the symbols `wav_data` and `wav_data_len` (rename if needed).
- Rebuild: `ninja -C build` and reflash the new UF2.
## Notes
- If playback is silent, double-check: WAV is PCM (not ADPCM/MP3), sample rate is non-zero, and the header file is included as `wav_data.h`.
- Playback continues with silence once the WAV data ends; reset or power-cycle to replay.