tinypod

tinypod is an iPod classic style music player that runs on real hardware using TinyGo.

tinypod uses tinyplayer to play audio using WAV files. It works with several different displays, can play songs on an SD card or in flash, and can use a configurable set of buttons based on your specific needs.

Supported Devices

Here are a few built-in supported device configurations:

Device	Folder	Display	Songs	Input	Audio
xiao-esp32c3 or xiao-rp2350 on the Seeed XIAO expansion board	devices/xiao-expansion	SSD1306 128x64	microSD card	Gamepad QT, or the board button	I2S DAC
Pico 2	devices/pico2-ssd1306	SSD1306 128x64	flash, USB drive	4 buttons	I2S DAC
Gopher badge	devices/gopher-badge	ST7789 320x240 color	flash, USB drive	6 badge buttons	speaker

See DEVICES for more information and how to add your own.

Build and flash

tinygo flash -tags fat_noexfat -target=xiao-rp2350 ./devices/xiao-expansion
tinygo flash -tags fat_noexfat -target=xiao-esp32c3 ./devices/xiao-expansion
tinygo flash -tags fat_noexfat -target=pico2 ./devices/pico2-ssd1306
tinygo flash -tags fat_noexfat -target=gopher-badge ./devices/gopher-badge

The serial output will show the number of songs and albums discovered by tinypod when it first starts up.

Songs

Put WAV files in folders under /Music. Each folder is an album. Files in one level of subfolders are added to the album too. If there is no /Music folder, tinypod uses the root of the volume.

/Music/Album One/01 Song.wav
/Music/Album One/02 Song.wav
/Music/Album Two/Disc 1/01 Song.wav
/Music/Single.wav

The song name on the screen is the file name without .wav. The album name is the folder name.

Use ffmpeg to make the files. 16 bit PCM sounds best. IMA ADPCM files are 4 times smaller, which helps when songs are in flash.

ffmpeg -i in.mp3 -ac 2 -ar 44100 -c:a pcm_s16le out.wav
ffmpeg -i in.mp3 -ac 2 -ar 22050 -c:a adpcm_ima_wav out.wav

SD card

Use a FAT32 microSD card of 4 GB to 32 GB (SDHC). tinypod mounts the card read only and never writes to it.

Flash and USB drive

On boards with songs in flash, the board shows up as a USB drive named tinypod. The first time, tinypod formats the flash. Copy WAV files to the drive. One second after the copy ends, tinypod stops playback, reads the songs again and goes back to the main menu.

Device	Flash	Space for songs	22.05 kHz stereo ADPCM
Pico 2	4 MB	3 MB	about 2.4 minutes
Gopher badge	8 MB	6 MB	about 4.8 minutes

22.05 kHz stereo ADPCM uses about 22 KB per second. Mono ADPCM at 16 kHz uses 8 KB per second and gives about 6.5 and 13 minutes.

Controls

tinypod uses these controls. Each device maps its buttons to them.

Event	Menus	Now Playing
Up, Down	Move	Volume
Left	Back	Previous song, or start of song after 3 seconds
Right	Open	Next song
Select	Open	Play/pause
Back	Back	Back to menus
PlayPause	Play/pause	Play/pause
VolumeUp, VolumeDown	Volume	Volume
Next, Previous	Next or previous song	Next or previous song

If nothing is playing, PlayPause plays all songs from the start.

How it works

tinypod consists of four main subsystems:

• Display Display shows what is going on to the user of the tinypod. See display.go and splash.go.

• Input Input reads whatever buttons are connected so that the user can operate the tinypod. See input.go.

• Library Library provides access to the actual music on the tinypod. It uses the Storage interface to be able to find albums and songs on SD card or flash memory. See library.go and storage.go.

• Deck Deck is what actually plays back the music so the user can hear it. See deck.go.

app.go connects them. It reads events from Input, runs the menus, tells Deck what to play from Library, and draws on Display.

Known issues

• tinypod on an SD card needs the sd fix in tinygo-org/drivers#905. Without it, the SD card does not mount.
• go.mod uses the branch of this PR until it is merged.
• The sd package reads several blocks at a time correctly only on SDHC cards. Do not use cards of 2 GB or less.
• Cards of 64 GB or more usually come formatted as exFAT. Format them as FAT32.
• The ColorTheme font is Noto Sans from tinyfont, under the SIL Open Font License.

License

Apache 2.0, see LICENSE.