Pico-Audio

Audio Expansion Module for Raspberry Pi Pico
Concurrently Headphone / Speaker Output

Overview

Provide Pico C demo.

Introduction

The Pico-Audio is an audio expansion module designed for Raspberry Pi Pico, which incorporates PCM5101A low power stereo decoder, and uses I2S bus for transmitting the audio signals. It supports a wide range of audio sampling rates, and allows headphone and speaker signal output at the same time.
Rev2.1 version: This product is an audio module designed based on Pico. It adopts a CS4344 low-power stereo decoder, an I2S interface to transmit audio, and supports a wide range of audio sampling frequencies. It also can be output by headphones and speakers at the same time.

Features

Support audio sampling frequency of 8~384,000Hz.
Using 3-wire I2S, effectively reducing EMI.
With undervoltage protection and a double mute system, it can automatically mute (stop output) when there is a clock error or power failure.
Provides 20dB of out-of-band noise.
Onboard standard 3.5mm headphone and 4-wire speaker output interface, support audio output.
Provides Pico sound card, driver-free driver, compatible with Windows, Linux and other systems.
Pico audio player provided.

Rev2.1:

Support audio sampling frequency of 2~200KHz.
The chip has a built-in PLL, and the audio clock pin can obtain the main clock screen and automatically reduce the frequency.
Onboard standard 3.5mm headphone and 4-wire speaker output interface, support audio output.
Provides Pico sound card driver-free program, compatible with Windows, Linux and other systems.
Pico audio player provided.

Specification

Operating voltage: 5V
Logic voltage: 3.3V
Audio Decoder: PCM5101A
DAC SNR: 106 dB
Logic level: 3.3V
Audio bus: I2S
Speaker driving: 2.6W/channel (4Ω BTL)
Earphone driving: 40W per channel (16@Ω 3.3V)

Rec2.1

Operating voltage: 5V
Logic voltage: 3.3V
Audio Decoder: CS4344
DAC SNR: 105 dB
Logic level: 3.3V
Audio bus: I2S
Speaker driving: 2.6W/channel (4Ω BTL)
Earphone driving: 40W per channel (16@Ω 3.3V)

Hardware Resource

Initial Version

L+ and L- correspond to the positive and negative poles of the left speaker respectively; R+ and R- correspond to the positive and negative poles of the right speaker respectively.

Pin Function	Pico Pins (BCM)	Description
VSYS	VSYS	Power supply (5V power input)
3V3(OUT)	3V3(OUT)	Logic Power (3.3V Power Input)
GND	GND	Power Ground
DIN	GPIO26	Audio data input
BCk	GPIO27	Audio data bit clock input
LRCK	GPIO28	Audio data word clock input

Rev2.1 Version

L+ and L- correspond to the positive and negative poles of the left speaker respectively; R+ and R- correspond to the positive and negative poles of the right speaker respectively.

Function Pin	Pico Pin（BCM）	Description
VSYS	VSYS	Power supply (5V)
GND	GND	Ground
DIN	GPIO22	Audio data input
MCLK	GPIO26	Chip main clock input
LRCK	GPIO27	Audio data word clock input
SCLK	GPIO28	Audio data bit clock input

I2S

The most important thing to note about the I2S protocol is that it takes the second clock after the change of the sampling pulse as the first bit of data, and the first clock after the change of the following sampling pulse as the last bit of data.
LRCK: Audio data word clock input, when it is low level for the left channel data acquisition when it is a high level for the right channel data acquisition.
BCK: Audio data word clock input, when it produces a rising edge jump to collect data, the frequency must be 32 or 48 or 64 times the frequency of LRCK.
DATA: Audio data input, note that the data is signed data, data transmission can choose 16-bit, 24-bit, 32-bit data, high in the front, low in the back.

Get Started with Pico

Hardware Connection

Please take care of the direction when connecting the board to Pico/Pico2 according to the USB port.
You can also wire it according to the table:


PCM5101A	Pico/Pico2	Description
VSYS	VSYS	Power input (5V)
3V3(OUT)	3V3(OUT)	Logic level (3.3V)
GND	GND	Ground
DIN	GPIO26	Audio data input
BCk	GPIO27	Audio data bit clock input
LRCK	GPIO28	Audio data word clock input

Pico-Audio Rev2.1	Pico/Pico2	Description
VSYS	VSYS	Power supply (5V)
GND	GND	Ground
DIN	GPIO22	Audio data input
MCLK	GPIO26	Chip main clock input
LRCK	GPIO27	Audio data word input
SCLK	GPIO28	Audio data bit input

Download Examples

Open a terminal of Raspberry Pi and run the following commands:

sudo apt-get install p7zip-full
cd ~
sudo wget  https://files.waveshare.com/upload/5/5a/Pico_Audio.7z
7z x Pico_Audio.7z -o./Pico-Audio
cd ~/Pico_Audio

Please use the following command for Rev2.1:

sudo apt-get install p7zip-full
cd ~
sudo wget  https://files.waveshare.com/upload/5/5a/Pico-Audio-V2.7z
7z x Pico-Audio-V2.7z -o./Pico-Audio-V2
cd ~/Pico-Audio-V2

There are two folders in the Pico_Audio file, the audio output program is stored in the Pico_Audio folder, and the uf2 file of the sound card is stored in the usb_sound_card folder, which can be copied directly into Pico/Pico2.

cp usb_sound_card.uf2  /media/pi/RPI-RP2/

Run Examples

C Codes

The following tutorials are operated on the Raspberry Pi, but due to the multi-platform and portable characteristics of CMake, it can be compiled successfully on the PC, but the operation is slightly different, and you need to judge by yourself.
Go into the Pico-Audio directory and build the codes.

cd ~/Pico_Audio/Pico-Audio/

Please use the following command for Rev2.1.

cd ~/Pico-Audio-V2/Pico-Audio/

Create a "build" folder and enter, add the path of SDK:
../../pico-sdk is the default path of SDK, you need to modify it if the actual path is different in your pi.
We have created the build folder in the example, you can just enter it.

cd build
export PICO_SDK_PATH=../../pico-sdk

Run cmake to generate Makefile file:

#Pico
cmake -DPICO_BOARD=pico -DPICO_PLATFORM=rp2040 ..
#Pico2
cmake -DPICO_BOARD=pico2 -DPICO_PLATFORM=rp2350 ..

Run make command to build the codes:

make -j9

After building, the uf2 file is generated.
Press and hold the key on the Pico board to connect the Pico/Pico2 to the USB port of the computer through the Micro USB cable, then release the key. After plugging in, the computer will automatically recognize a removable disk (RPI-RP2). Copy the audio_firmware.uf2 file in the build folder to the removable disk (RPI-RP2) recognized.

#Pico
cp audio_firmware.uf2  /media/pi/RPI-RP2/
#Pico2
cp audio_firmware.uf2  /media/pi/RP

Resource

Documents

Demo Codes

Development Software

Pico Getting Started

Firmware Download

MicroPython Firmware Download

C_Blink Firmware Download

Introduction

Raspberry Pi Pico Basics

MicroPython Series

Install Thonny IDE

In order to facilitate the development of Pico/Pico2 boards using MicroPython on a computer, it is recommended to download the Thonny IDE

Download Thonny IDE and follow the steps to install, the installation packages are all Windows versions, please refer to Thonny's official website for other versions
After installation, the language and motherboard environment need to be configured for the first use. Since we are using Pico/Pico2, pay attention to selecting the Raspberry Pi option for the motherboard environment

Configure MicroPython environment and choose Pico/Pico2 port
- Connect Pico/Pico2 to your computer first, and in the lower right corner of Thonny left-click on the configuration environment option --> select Configture interpreter
- In the pop-up window, select MicroPython (Raspberry Pi Pico), and choose the corresponding port

Flash Firmware

Click OK to return to the Thonny main interface, download the corresponding firmware library and burn it to the device, and then click the Stop button to display the current environment in the Shell window
Note: Flashing the Pico2 firmware provided by Micropython may cause the device to be unrecognized, please use the firmware below or in the package
- Pico firmware library
- Pico2 firmware library
How to download the firmware library for Pico/Pico2 in windows: After holding down the BOOT button and connecting to the computer, release the BOOT button, a removable disk will appear on the computer, copy the firmware library into it
How to download the firmware library for RP2040/RP2350 in windows: After connecting to the computer, press the BOOT key and the RESET key at the same time, release the RESET key first and then release the BOOT key, a removable disk will appear on the computer, copy the firmware library into it (you can also use the Pico/Pico2 method)

MicroPython Series

【MicroPython】 machine.Pin class function details
【MicroPython】machine.PWM class function details
【MicroPython】machine.ADC class function details
【MicroPython】machine.UART class function details
【MicroPython】machine.I2C class function details
【MicroPython】machine.SPI class function details
【MicroPython】rp2.StateMachine class function details

C/C++ Series

For C/C++, it is recommended to use Pico VS Code for development. This is a Microsoft Visual Studio Code extension designed to make it easier for you to create, develop, and debug projects for the Raspberry Pi Pico series development boards. No matter if you are a beginner or an experienced professional, this tool can assist you in developing Pico with confidence and ease. Here's how to install and use the extension.

Official website tutorial: https://www.raspberrypi.com/news/pico-vscode-extension/
This tutorial is suitable for Raspberry Pi Pico, Pico2 and the RP2040 and RP2350 series development boards developed by Waveshare
The development environment defaults to Windows. For other environments, please refer to the official tutorial for installation

Install VSCode

First, click to download pico-vscode package, unzip and open the package, double-click to install VSCode

Note: If vscode is installed, check if the version is v1.87.0 or later

Install Extension

Click Extensions and select Install from VSIX
Select the package with the vsix suffix and click Install
Then vscode will automatically install raspberry-pi-pico and its dependency extensions, you can click Refresh to check the installation progress
The text in the right lower corner shows that the installation is complete. Close VSCode

Configure Extension

Open directory C:\Users\username and copy the entire .pico-sdk to that directory
The Copy is completed

Open vscode and configure the paths for the Raspberry Pi Pico extensions

The configuration is as follows:

Cmake Path:
${HOME}/.pico-sdk/cmake/v3.28.6/bin/cmake.exe

Git Path:
${HOME}/.pico-sdk/git/cmd/git.exe    

Ninja Path:
${HOME}/.pico-sdk/ninja/v1.12.1/ninja.exe

Python3 Path:
${HOME}/.pico-sdk/python/3.12.1/python.exe

New Project

The configuration is complete, create a new project, enter the project name, select the path, and click Create to create the project
To test the official example, you can click on the Example next to the project name to select
The project is created successfully
Select the SDK version
Select Yes for advanced configuration
Choose the cross-compilation chain, 13.2.Rel1 is applicable for ARM cores, RISCV.13.3 is applicable for RISCV cores. You can select either based on your requirements
Select default for CMake version (the path configured earlier)
Select default for Ninjaversion
Select the development board
Click Complie to compile
The uf2 format file is successfully compiled

Import Project

The Cmake file of the imported project cannot have Chinese (including comments), otherwise the import may fail
To import your own project, you need to add a line of code to the Cmake file to switch between pico and pico2 normally, otherwise even if pico2 is selected, the compiled firmware will still be suitable for pico
set(PICO_BOARD pico CACHE STRING "Board type")

Update Extension

The extension version in the offline package is 0.15.2, and you can also choose to update to the latest version after the installation is complete

Arduino IDE Series

Install Arduino IDE

First, go to Arduino official website to download the installation package of the Arduino IDE.
Here, you can select Just Download.
Once the download is complete, click Install.

Notice: During the installation process, it will prompt you to install the driver, just click Install
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Arduino IDE Interface

After the first installation, when you open the Arduino IDE, it will be in English. You can switch to other languages in File --> Preferences, or continue using the English interface.
In the Language field, select the language you want to switch to, and click OK.

Install Arduino-Pico Core in the Arduino IDE

Open the Arduino IDE, click on the file in the top left corner, and select Preferences

Add the following link to the attached board manager URL, and then click OK

https://github.com/earlephilhower/arduino-pico/releases/download/4.0.2/package_rp2040_index.json

Note: If you already have an ESP32 board URL, you can use a comma to separate the URLs as follows:

https://dl.espressif.com/dl/package_esp32_index.json,https://github.com/earlephilhower/arduino-pico/releases/download/4.0.2/package_rp2040_index.json

Click Tools > Development Board > Board Manager > Search pico, as my computer has already been installed, it shows that it is installed

Upload Demo at the First Time

Press and hold the BOOTSET button on the Pico board, connect the pico to the USB port of the computer via the Micro USB cable, and release the button after the computer recognizes a removable hard disk (RPI-RP2).
Download the program and open D1-LED.ino under the arduino\PWM\D1-LED path
Click Tools --> Port, remember the existing COM, do not click this COM (the COM displayed is different on different computers, remember the COM on your own computer)
Connect the driver board to the computer using a USB cable. Then, go to Tools > Port. For the first connection, select uf2 Board. After uploading, when you connect again, an additional COM port will appear
Click Tools > Development Board > Raspberry Pi Pico > Raspberry Pi Pico or Raspberry Pi Pico 2
After setting it up, click the right arrow to upload the program

If issues arise during this period, and if you need to reinstall or update the Arduino IDE version, it is necessary to uninstall the Arduino IDE completely. After uninstalling the software, you need to manually delete all contents within the C:\Users\[name]\AppData\Local\Arduino15 folder (you need to show hidden files to see this folder). Then, proceed with a fresh installation.

Open Source Demos

MircoPython video demo (github)
MicroPython firmware/Blink demos (C)
Raspberry Pi official C/C++ demo (github)
Raspberry Pi official micropython demo (github)
Arduino official C/C++ demo (github)

FAQ

Question:How to get the Pico-Audio to play audio files?

Answer:

Due to the memory limitation of Pico, it is not possible to store wav or mp3 files. So we don't provide a py demo that can play WAV or mp3, we suggest using our C demo, and you can find it in Demo code.

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Support

Technical Support

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