Audio Player with Raspberry Pi Pico 2W
Audio player for headphones or devices with 3.5 jack.
Author: Rusu Carla-Maria
GitHub Project Link: link_to_github
Description
This project implements a compact WAV audio player using the Raspberry Pi Pico 2W microcontroller. The audio files are stored on a microSD card, read via SPI, and played through an I2S DAC (UDA1334A) connected to a 3.5mm headphone jack. The user can use the push buttons and the rotary encoder to customize the experience.
Motivation
The motivation for choosing this project was to explore embedded audio playback using Rust and Embassy on the Raspberry Pi Pico 2W. The goal was to build a music player while learning low-level embedded I/O, SPI, I2S, and async execution using Rust.
Architecture
Components Overview
| Component | Responsibility |
|---|---|
| Audio Handler | Reads WAV files and streams audio via I2S to the DAC |
| SPI Handler | Interfaces with the SD card to access audio files and with the LCD to display information |
| UI | Displays UI (e.g., file list, song name, progress) |
| Input Handler | Processes rotary encoder and buttons |
| Playback Controller | Controls playback state (play/pause, skip, etc.) |
Interconnection
- Input Handler dictates the state of the Playback Controller
- Playback Controller coordinates with Audio Manager and SPI Handler to stream audio.
- Audio Handler uses SPI Handler to get WAV file data.
- Playback Controller notifies UI to update the screen.
Diagram
Log
Week 5 - 11 May
Week 12 - 18 May
Week 19 - 25 May
Hardware Design
Hardware Description
The following hardware was used:
- Raspberry Pi Pico 2W
- UDA1334A I2S DAC with 3.5mm jack socket
- LCD with built-in SD slot (will see if this is the best option)
- Rotary Encoder
- 3 push buttons
- Breadboards and jumper wires
Schematic
Tried to do something in Kicad (not for dark mode)
Bill of Materials
| Item | Quantity | Unit Price (RON) | Total (RON) | Usage |
|---|---|---|---|---|
| Raspberry Pi Pico 2W | 1 | 39.66 | 39.66 | Main controller |
| Raspberry Pi Pico (debug / Picoprobe) | 1 | 39.66 | 39.66 | Used for SWD debugging |
| UDA1334A I2S DAC Module | 1 | 56.76 | 56.76 | Audio output module |
| LCD SPI Display 1.8" (128x160) with SD slot | 1 | 28.99 | 28.99 | Used for UI and SD (via SPI) |
| Push Button (white round cap) | 3 | 1.99 | 5.97 | Controls |
| Rotary Encoder Module | 1 | 4.99 | 4.99 | Controls |
| 10k Stereo Potentiometer | 1 | 1.99 | 1.99 | Analog Control (ADC input) |
| Breadboard HQ (830 points) | 2 | 9.98 | 19.96 | For main Pico + Picoprobe wiring |
| Header pins (2.54 mm, 40p) | 2 | 0.99 | 1.98 | For soldering Pico and accessories |
| Female Breakable Header (40p) | 1 | 2.56 | 2.56 | Extra connectivity (LCD/SD) |
| Breadboard rigid wires | 1 | 12.49 | 12.49 | Neat wiring on breadboard |
| Breadboard jumper wires | 1 | 7.99 | 7.99 | General-purpose jumpers |
Total Estimated Cost: 229.60 RON (for now)
Software
To-do : complete later when I've finished
Dependencies Overview
| Library | Description | Usage |
|---|---|---|
| embassy | Async embedded framework | Core runtime for async tasks and peripherals |
| embassy-rp | HAL for Raspberry Pi Pico (RP2040) | Controls GPIOs, SPI, I2S, etc. |
| embedded-graphics | 2D graphics library | Used for drawing text and shapes on LCD |
| mipidsi | Generic MIPI DSI display driver | Driver for ST7735 LCD |
| display-interface-spi | SPI display abstraction | Connects the embedded-graphics to SPI-based displays |
| embedded-sdmmc | FAT filesystem over SD card | Used to read .wav files from SD card |
| embedded-hal | Traits for embedded devices | Base for SPI, I2S, ADC, GPIO, etc. |
| defmt | Logging crate for embedded | For debugging and structured logs |
| micromath | Lightweight math functions | Used for simulations of sound waves |
Links
- PIO Programs : Helped me with drivers for I2S and Rotary Encoder