picoAUDIO

The audio solution dedicated to the TinyPICO.

About

Purchased units are fully assembled as per the main image

The picoAUDIO is a fully featured audio solution specially made for the TinyPICO ESP32 development board, featuring an I2S Stereo DAC, I2S Mono MEMS Microphone, builtin 3.7W Stereo Amplifier, dedicated Headphone Amplifier, I2C GPIO Extender and built-in MicroSD card reader.

We utilise a low power NXP UDA1334A IC featuring a clear digital 16/20/24 bit, 44.1kHz, stereo audio DAC. Accompanying the DAC is a Knowles SPH0645 I2S digital mono microphone. This miniature low power MEMS microphone provides a low noise, 24 bit, 44.1kHz stream. Complimenting the DAC is the powerful Maxim MAX98306 3.7W stereo class D amplifier with stero speaker terminals and a Texas Instrumets TPA6132A2 stereo headphone amplifier with 3.5mm audio jack.

A simple mounting socket hosts the TinyPICO development board and connects all of these great features together in a seamless and easy to utilise footprint measuring a tiny 33 mm x 57 mm (1.29in x 2.24in). To provide maximum connectivity the board features a built-in MicroSD card reader and GPIO extender to hookup 8 inputs and outputs for all of your button and LED needs.

Why use a DAC like this?

While the ESP32 does have two built-in DACs that are capable of generating stereo audio, the accuracy of these DACs is severely limited when compared to the dedicated audio codec found on the picoAUDIO. The default ESP32 DACs are 8bit whereas the picoAUDIO's DACs can operate at 16, 20 or 24bit. This is a much higher resolution, providing higher fidelity sound for your audio projects. Coupled with the built in microSD card reader you will be playing high quality audio in no time.

While a lot of audio boards provide an audio jack to connect your device to an external amplifier, few boards provide a properly amplified headphone audio jack. Many boards utilise large capacitors to drive headphones but create significant noise and distortion as a result. The picoAUDIO board uses a dedicated Texas Instruments headphone amplifier with selectable gain to provide high fidelity headphone audio.

Features

The software and hardware used in this project has been made possible by the principle of open hardware and software. Many of the samples have been collected together from a variety of authors and edited to work out of the box with the picoAUDIO for instructional purposes. Please consult each sample project for relevant license and credit.

The picoAUDIO board is an open hardware project. All Eagle CAD schematics, PCB layout files and gerbers are provided on GitHub and distributed under the MIT license.

TinyPICO Compatible

• Simply plug your TinyPICO board into the picoAUDIO and your ready to go

Audio Out

• Switching amplified 3.5mm headphone jack. Plug in headphones without distortion or use it as a line out to an external device.
• Stereo screw clamp audio terminals. The speaker terminals automatically mute when the 3.5mm jack is used.

Built-in MicroSD Card

• Quality Molex mechanism
• Simple SPI interface
• Activity LED light
• Push-Push socket with overhanging edge mounted card for easy insertion

UDA1334A Stereo DAC

• Low power audio DAC
• Integrated digital filter and switchable digital de-emphasis for 44.1 kHz frequency
• Supports samples from 16 to 100 kHz
• Simple I2S interface
• 16/20/24 bit audio
• High linearity, wide dynamic range and low distortion

MAX98306 Stereo Amplifier

• Low power efficient operation
• 3.7W @ 3Ohm, 10% THD / 1.7W at 8Ohm, 10% THD
• Spread Spectrum Modulation
• Five selectable gain levels
• Excellent click and pop suppression
• Stereo screw terminals

TPA6132A2 Headphone Amplifier

• 25mW Headphone Amplifier for 16/32Ω Headphones with 3.5mm Audio Jack
• Unlike most audioboards, the picoAUDIO features a dedicated headphone amplifer
• Doesn't use caps to drive headphone audio, reducing unwanted noise and distortion
• Click and pop supression
• Low power amplifier @ 2.1mA typical supply current
• Four selectable gain levels
• 3.5mm audio jack

SPH0645LM4H MEMS Microphone

• Low power design
• Simple I2S interface
• Flat frequency response
• 24 bit, 44.1kHz audio
• High SNR of 65dB(A)
• RF shielded
• Omnidirectional

PCF8574 GPIO Expander

• 8 ports
• Use each port as an input or output
• Directly drive LEDs for status
• Add additional buttons to control your projects

Add ons

• Care has been taken to ensure access to both the I2C and SPI bus with additional CD and DC pins available.
• Add an SPI TFT screen to your project and display a graphic equaliser
• Add an LCD character display and provide user feedback and audio metadata
• Examples with 320x240 TFT showing Graphic equalizer (FFT) and 2x16 character LCD provided
• An additional LDO voltage regulator has been placed on the picoAUDIO to drive several components directly from USB power, allowing the easy addition of higher powered peripherals without overloading the TinyPICO voltage regulator.