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    MCU/MPU/DSP > Development Platforms & Kits > Daughter / Add-on boards >
    • Wolfson Audio Card for Raspberry Pi
    • Wolfson Audio Card for Raspberry Pi
    • Wolfson Audio Card for Raspberry Pi

    Overview

    The Wolfson and element14 introduce an audio card to offer Raspberry Pi users the ability to capture audio alongside their camera, and experiment with stereo digital capture and playback.

    Raspberry Pi, whilst doing a fantastic job of being a small and powerful computer, does this by a number of compromises. One of those is the limitations on its audio capabilities. Out of the box, Raspberry Pi provides good quality audio across the HDMI link, lower quality stereo audio by way of its 3.5 mm stereo jack, but no capability to connect microphones or other external audio sources, such as attaching directly to loudspeakers.

    The Wolfson Audio Card solves this by providing similar audio flexibility that would be provided by a PC soundcard. Not only this but the Wolfson Audio Card was produced in partnership with Wolfson, the premier audio solutions chip company, to produce superior sound capabilities for the Raspberry Pi.

    The Wolfson Audio Card is based on Wolfson WM5102 audio hub codes. The WM5102 is a highly-integrated low-power audio system for smartphones, tablets and other portable audio devices. It combines wideband telephony voice processing with a flexible, high-performance audio hub CODEC. The WM5102 digital core provides a powerful combination of fixed-function signal processing blocks with a programmable DSP. These are supported by a fully-flexible, all-digital audio mixing and routing engine with sample rate converters, for wide use-case flexibility. Two stereo headphone drivers each provide stereo ground-referenced or mono BTL outputs, with noise levels as low as 2.3μVRMS for hi-fi quality line or headphone output. The CODEC also features stereo 2W Class-D speaker outputs, a dedicated BTL earpiece output and PDM for external speaker amplifiers. A signal generator for controlling haptics devices is included; vibe actuators can connect directly to the Class-D speaker output, or via an external driver on the PDM output interface. All inputs, outputs and system interfaces can function concurrently.

    Important Note: Please be aware that the Wolfson Audio Card is only compatible with Raspberry Pis which feature the P5 pads, which can be found on Revision 2 Raspberry Pis onwards.

    Key Applications: Audio

    Features

    • 3.5 mm jack (4-pole) for a headset/boom mic combination for gaming or VoIP applications
    • 3.5 mm jack for microphone input
    • On-board MEMS microphone
    • 3.5 mm jack stereo line input for connection to devices such as digital audio players (iPod etc.) or mobile phones
    • 3.5 mm jack stereo line output for connection to devices such as external stereo amplifiers or powered speakers
    • Phono jack for electrical (not optical) S/PDIF digital input
    • On-board class D power amplifier for external speakers, with connection to external power source if needed.
    • Small pin header for extra functions if they are low cost, already on-chip, and don’t require any further components
    • Raspberry Pi form factor

    Ships With

    • WOLFSON AUDIO CARD

    FAQs

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    What are the audio rendering capabilities of Wolfson Audio Card?
    The Wolfson Audio Card capable of rendering HD Audio at 24-bit, 192kHz.
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    Is Wolfson Audio Card Compatible with Accessory expanders like Pi Face, Pi Rack?
    No, it is not compatible with accessory expanders like Pi face, Pi Rack since they usually only expand Raspberry Pi’s P1 GPIO expansion port, and not the P5, which is essential for audio.
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    How do I install software to run on Raspberry Pi?
    The software required to run the Wolfson Audio Card is downloaded as a fully integrated all-in-one package that will simply work out of the box.
    (1) Download recent image file from "www.element14.com/wolfson"
    (2) The file .img has been compressed in to a .zip format. Extract it and save it in desired location. Next, the .img file needs to be installed to the sd card, hence "Win32DiskImager" need to be installed from link "https://launchpad.net/win32-image-writer"
    (3) Follow the instructions provided with Win32DiskImager for writing the operating system to SD card. Insert SD card in to a SD card slot on your computer and browse for the unzipped .img file and write it on SD card
    (5) Now insert the SD card in to the SD card slot of Raspberry Pi and power up both Raspberry Pi and Wolfson Audio card.
    (6) The image has been designed to boot into the Graphical User Interface, so that when the boot process has been completed, you should see a desktop, then you are ready to go.
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    How do I connect external speakers to Wolfson Audio Card ?
    The Wolfson Audio card contains an on board Class D power amplifier, capable of delivering up to 1.4W per channel, directly to external loudspeakers. The Connectors required to allow this are in locations J6 (left) and J3 (right), but they are not populated as standard. Before playing a file to your speakers, you must run the appropriate Use Case Script to play to loudspeakers, then play a file using the LXmusic player.
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    Is there any considerations for SD Card speed class when used to record or playback HD audio on Wolfson Audio Card?
    If you are recording to, or playing back from your SD card, It is Important that you use an SD card that is class 6 and above. The class directly correlates with speed of reading and writing to the card. When playing HD audio, the rate of data being read from the card is significant, and a low card will leave occasional gaps in the audio experience, similarly when recording.

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