An open-source, Arduino-compatible, ESP32-based audio development board

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PICO DSP is an open source, Arduino compatible ESP32 development board for audio and digital signal processing (DSP) applications. It offers a fully functional feature set for audio processing on a small format breadboard friendly device, and includes audio inputs and audio outputs, a low-noise microphone array, integrated test speaker option, additional memory, battery charge management and ESD protection all on the same PCB.

Synthesizers, Installations, Voice UI, and More

PICO DSP can be used for a wide range of digital signal processing applications, including but not limited to those in the fields of music, art, creative and adaptive technology. Music related examples include digital music synthesis, smart musical instrument design, mobile recording, Bluetooth speakers and wireless line-level directional microphones. Art related examples include sound-art installations, acoustic sensor networks and internet radio. Creative and adaptive technology related examples include voice user interface (VUI) design and web audio for the Internet of Sounds.

Features & Specifications

Processor & Memory

  • Espressif ESP32 Pico D4 processor
  • 32-bit dual-core 80 MHz / 160 MHz / 240 MHz
  • Choice of either 4 MB SPI Flash with 8 MB additional PSRAM or 16 MB External SPI Flash
  • Wireless 2.4 GHz Wi-Fi -802.11b/g/n
  • Bluetooth BLE 4.2
  • 3D antenna


  • Wolfson WM9878 Stereo Audio Codec
  • Audio Line In on stereo 3.5 mm connector
  • Audio Headphone / Line Out on stereo 3.5 mm connector
  • Stereo Aux Line In, Audio Mono Out routed to GPIO Header
  • 2 x Knowles SPM0687LR5H-1 MEMS microphones routed in low-noise differential configuration, can be configured as broadside or end-fire beam forming microphone arrays
  • ESD protection on all audio inputs and outputs
  • Support for 8, 11.025, 12, 16, 22.05, 24, 32, 44.1 and 48 kHz sample rates
  • 1 W Speaker Driver, routed to GPIO Header

Form Factor and Connectivity

  • Breadboard friendly
  • 70 mm x 24 mm
  • 11 x GPIO pins broken out to 2.54mm pitch header, with access to both ESP32 ADC channels, I2C and capacitive touch pins
  • USB 2.0 over USB Type C connector


  • 3.7/4.2 V Lithium Polymer Rechargeable Battery or USB / External 5 V Powered
  • ESP32 and Audio Codec can be placed into low power modes under software control
  • Power consumption in normal usage (Wi-Fi off, running audio DSP code with mics active) = 100 mA, with Audio Codec in standby mode = 52.4 mA, low power usage (Audio Codec in standby mode and ESP32 in deep sleep mode) = 5.7 mA
  • Battery voltage level detection
  • ESD protection on USB data bus

Open Source

PICO DSP is a 100% open source project! The creators of this project believe strongly in the benefits of open source design and if you are reading this then we are interested in your contributions to the project too. PICO DSP was designed to create a reliable development board for audio applications with all the necessary hardware documentation easily available, and we believe there are currently unexplored applications of the hardware.

When the project launches, all the hardware design files (Eagle schematic and board files) and example software files will be available in a public repository on Github. As we progress through the campaign we’ll be having a look in more detail at the different aspects of the hardware design, and if there are any questions we’ll be on hand to answer them.

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