PÚCA DSP

PÚCA DSP is an open source, Arduino compatible ESP32 development board for audio and digital signal processing applications. In this repository you will find the hardware design files, and software examples for;

• Arduino IDE
• VSCode/PlatformIO with Platform Espressif 32 and Framework arduinoespressif32
• VSCode/PlatformIO with Platform Espressif 32 and Framework espidf
• ESP IDF

Specifications

Processor & Memory

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

Audio

• Wolfson WM8978 Stereo Audio Codec
• Audio Line In on stereo 3.5mm connector
• Audio Headphone / Line Out on stereo 3.5mm connector
• Stereo Aux Line In, Audio Mono Out routed to GPIO Header
• 2 x Knowles SPM0687LR5H-1 MEMS Microphones
• ESD protection on all audio inputs and outputs
• Support for 8, 11.025, 12, 16, 22.05, 24, 32, 44.1 and 48kHz sample rates
• 1W Speaker Driver, routed to GPIO Header
• DAC SNR 98 dB, THD -84 dB (‘A’ weighted @ 48 kHz)
• ADC SNR 95 dB, THD -84 dB (‘A’ weighted @ 48 kHz)
• Line input impedance: 1 M ohm
• Line output impedance: 33 ohm

Form Factor and Connectivity

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

Power

• 3.7/4.2v Lithium Polymer Rechargeable Battery, USB or external 5V DC power source
• ESP32 and Audio Codec can be placed into low power modes under software control
• Battery voltage level detection
• ESD protection on USB data bus

Documentation

Pin Description

Absolute Maximum Ratings

Maximum voltage before clipping on Audio Input, Aux L & Aux R = 3.3V peak-to-peak, AC. Audio input paths are AC coupled.

Maximum voltage on GPIO pins = 3.3V DC. GPIO pins are not overvoltage protected, for voltages higher than 3.3V use an input protection circuit such as a diode clamp or a level shifter.

Current Consumption Characteristics

Battery Voltage Monitoring

Battery voltage monitoring is available by soldering the BT_LVL solder jumper on the PCB top side, which routes the battery voltage to GPIO 14.

Physical Dimensions

*Height measurement is with pin headers soldered.

Open Source Licensing

PÚCA DSP is Open Source Hardware Association certified, and can be found on the OSHWA website here; https://certification.oshwa.org/list.html

Hardware design files are released as open source under the CERN v1.2 license. PÚCA DSP software examples are released under the MIT license, software examples using Faust DSP also contain additional license information relevant to Faust DSP. Please review these licenses before using these files in your own projects to understand your obligations.

Video Tutorials

1. Getting started with VS Code and PlatformIO IDE - https://www.youtube.com/watch?v=hKllKXUncVo
2. Configuring the audio codec - https://www.youtube.com/watch?v=Auh9VE7Pjl8

Need a board?

There are a few available on Tindie - https://www.tindie.com/products/ohmic/puca-dsp/