tinyplayer

Play WAV audio on TinyGo devices using an I2S DAC such as the PCM5102 or MAX98357.

• Sound effects, speech and music
• 8 and 16 bit PCM, and IMA ADPCM, mono or stereo, at any sample rate the I2S hardware supports
• Audio embedded in the program, or in WAV files on a FAT volume in flash
• On boards with USB, the flash volume shows up as a USB drive so you can copy WAV files to it

The ESP32 and nRF52 I2S drivers are in the TinyGo dev branch.

out := &machine.I2S0
out.Configure(machine.I2SConfig{
	SCK:    machine.GPIO3,
	WS:     machine.GPIO4,
	SDO:    machine.GPIO5,
	SDI:    machine.NoPin,
	Mode:   machine.I2SModeSource,
	Stereo: true,
})

player := tinyplayer.New(out)
player.Play(strings.NewReader(sound))

Play takes any io.Reader with a WAV file in it. It sets the sample rate from the file and returns when all the audio is queued. Call Stop from another goroutine to end playback early. SetVolume takes 0 to 256.

To embed a sound use a string so it stays in flash:

//go:embed beep.wav
var beep string

flashdisk makes a region of NOR flash usable as a disk with 512 byte sectors. It erases flash only when it has to. storage mounts a FAT volume on it using github.com/soypat/fat, and formats it the first time.

disk, _ := flashdisk.Tail(machine.Flash, 1<<20)
vol, _, _ := storage.Mount(disk)
names, _ := vol.ListWAV(nil)

var f fat.File
vol.Open(&f, names[0])
player.Play(&f)
f.Close()

The same disk can be passed to msc.Port to show it as a USB drive.

Wiring for the examples:

• examples/embed plays sounds built into the program.

  tinygo flash -target=xiao-esp32c3 ./examples/embed
  

• examples/flash plays the WAV files on the flash volume. If there are none it copies the example sounds there first.

  tinygo flash -tags fat_noexfat -target=xiao-esp32c3 ./examples/flash
  

• examples/msc shows the flash volume as a USB drive. Copy WAV files to it and they play once the copy is done.

  tinygo flash -tags fat_noexfat -target=pico ./examples/msc
  

The fat_noexfat tag leaves out exFAT support, which these small volumes do not need.

Mono IMA ADPCM at 16 kHz is a good choice for speech and effects. It uses about 8 KB per second.

ffmpeg -i in.mp3 -ac 1 -ar 16000 -c:a adpcm_ima_wav out.wav

16 bit PCM for the best quality:

ffmpeg -i in.mp3 -ac 2 -ar 44100 -c:a pcm_s16le out.wav

examples/sounds/generate.sh makes the example sounds.

• On ESP32-C3 the ROM flash routines refuse writes past 2 MiB, so the example volume ends there.
• ESP32-S3 has no machine.Flash yet.
• RP2040 and RP2350 need the DMA and sample rate fixes to piolib.I2S from tinygo-org/pio#64. go.mod uses the pio main branch until the next release.