Wolfson Raspberry Pi Soundcard Manual (.IMG install)
Contents
1. Audio Function Script to run 1 Play an audio file to your headphones Playback_to_Headset sh 2 Play an audio file to the line out jack Playback_to_Lineout sh 3 Play an audio file to loudspeakers Playback_to_Speakers sh 4 Play an audio file to the SPDIF output of SPDIF_playback sh your card 5 Record from onboard digital Record from _DMIC sh microphones 6 Record from the boom microphone of Record_from_Headset sh your gamer VoIP headphones 7 Record from the analogue Line In socket Record_from_lineIn sh 9 Record from the SPDIF input of your SPDIF_record sh card 10 Reset all audio paths Reset _paths sh Table 1 A list of the Use Case Scripts for setting up the audio card As an example let us say that you want to play one of the bundled High Definition audio tracks that are included in the software package and you want to play it to your headset In this case and at the command line in LXTerminal type the following command Playback_to_Headset sh lt Enter gt The script will run and you will be returned to the command prompt again If at any time during the time the script runs you see the following message displayed on the screen amixer Cannot find the given element from control hw 0 This means the card was not detected and registered properly during start up It is recommended in this case that you check the card is properly secured to you2. Rload 10kOhms Typical Parameter Description Value Units Connector Electrical input via 3 pole 3 5mm Socket Rin Input Impedance 3dB down from 1kHz signal level at this frequency Full scale input signal Equivalent input noise level no signal applied Total Harmonic Distortion 0 9Vrms Input Test conditions as follows unless otherwise noted 48kHz sample rate test signal 1kHz sine wave and bandwidth measured is 20Hz to 20kHz Wav wolfsor elementiu Headphone Output Typical Parameter Description Conditions Value Units Connector Electrical output via 4 pole 3 5mm Socket Rout Output impedance Cload Max capacitive load on output Full scale output signal level note that the headphone use case script limits this to 0 5Vrms for safety Noise Floor no signal applied A weighting filter Total Harmonic Distortion 400mVrms output Test conditions as follows unless otherwise noted 48kHz sample rate test signal 1kHz sine wave bandwidth measured 20Hz to 20kHz Rload 320hms Headset Input Typical Parameter Description Value Units Electrical input via 4 pole 3 5mm Socket MIC Connector on Sleeve Vbias Microphone voltage bias level Rbias Microphone bias resistor 3dB down from 1kHz signal level at this Fcut frequency Full scale input signal 500mVrms to 14mVrms Vin depending on input gain setting Equivalent inpu
3. Linux Sound Architecture You can read more about this at www alsa project org In the OS download referred to in section 4 above the supported audio player is LXmusic and labelled Music Player on the desktop In general there are two main stages to performing an audio task whether that is to play a file or record one b The Use Case has to be defined first so that the sound device is configured properly A Use Case is simply a set of commands that are run in series which set the audio card up They define the signal paths for any audio that is played or recorded So for example if you want to play audio to speakers you d run the script for that case A script is a collection of commands that can be run in a single instruction The action to play record can then be executed The Use Case definition is set up by running one of a set of scripts that are supplied in the software package It is done this way To run any kind of script it is necessary to start a Terminal session Double click on LXTerminal on the desktop or indeed any other terminal programme you prefer The terminal allows you type commands directly instructing the OS to form operations you want to perform Start by typing dir That will give you a list of files and folders that are contained in the home directory that the Terminal session opens in A set of use cases have been put placed into this directory for you as follows VV Wolfson elementiu
4. it is necessary to tell the audio card to switch audio into the card from that source This is done by running the following command Record_from_lineIn sh lt Enter gt Now we need to use the arecord command to capture the audio to a specified file as follows arecord Dhw 0 c 2 f S16_LE r 44100 record from_line_in wav lt Enter gt Note the above should be entered as a single line and not two lines as shown here Recording will start Press CTRL C to stop recording A brief explanation of the options above is as follows c Number of channels Here we specify two for stereo Wav Wolfson elementiu Recording format In this case we are asking for 16 bit Little Endian r Sample rate We ask here for 44 100 audio samples per second 1 II To find out more about this command type arecord help lt Enter gt If you wish to compress the audio file into other formats there are other programmes that can be installed on Raspberry Pi to do this ffmpeg is such a programme available at www ffmpeg org Its use and implementation is beyond the scope of this document A General Warning If Editing Use Case Scripts Use case scripts can be adjusted to accommodate various types of sources In particular the gain of those inputs can be adjusted to make them very sensitive The result can be an extremely LOUD output signal It is always advisable to reduce the volume of any amplifier or active sp
5. 6 left and J3 right but they are not populated as standard 1 You can solder your own pair of male 0 1 headers by purchasing from Farnell Newark element14 Suggested models are as follows Region Distributor Part Number North America Newark 60H4177 Europe Farnell 9733302 Asia Pacific element14 9733302 Table 2 Suppliers of 0 1 headers Warning Once fitted be extremely careful not to accidently short the speaker pins Doing so could damage the Audio Card Itis necessary to supply auxiliary power to the Audio Card in order to drive external loudspeakers An external power supply with output voltage of 5V current delivery capability of 2 000mA a centre positive power plug of internal diameter 2 1mm and external diameter 5 5mm With your Raspberry Pi powered down connect speakers to the newly fitted headers Make sure your speakers are connected in phase To do this observe on the header pins that one pin is marked with a white dot Your speaker cable should be polarised as well with perhaps one core being coloured red and the other black Be consistent with how you connect for example the red cable goes to the connector with the dot on both pins 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 Connecting your audio card to a SPDIF sink VV Wwolfsory elementiu You can conn
6. Pi Face Pi Rack as they usually only expand Raspberry Pi s P1 GPIO expansion port and not the P5 which is essential for audio The nylon pillar is essential for reliable operation of the soundcard It holds the soundcard mechanically stable to ensure the sprung connectors make a good electrical connection with the Raspberry Pi P5 connector The use of USB hubs with Raspberry Pi and the Wolfson Audio Card is not recommended VV wolfson elementiu 4 Installing software to run on Raspberry Pi This version of the manual is written for early adopting users The software required to run the card is downloaded as a fully integrated all in one package that will simply work out of the box We have created a full operating system solution that contains all the drivers and some bundled extras It will work straight away when downloaded written to an SD Card and set up for the first time 7 Download the most recent image file from www element14 com wolfson and save it in a known location on your Windows computer The file can be quite large so be patient as the file downloads The file img has been compressed into a zip format in order to minimise download time That means before you can do anything else that file needs to be restored to its original form again You may already have a zip unzip tool installed on your computer check by right clicking on the zip file if you see the Extract all option then you have i
7. Wav Wolfson elementiu Wolfson Audio Card User Documentation Contents 1 2 3 4 5 6 7 Introduction to Wolfson Audio Card for Raspberry Pi Features How to install to Raspberry Pi Installing software to run on Raspberry Pi Getting started with audio from your Wolfson Audio Card Soundcard usage scenarios Annexe a Datasheet of WM5102 audio CODEC Datasheet of WM8804 SPDIF receiver transmitter Datasheet of WM7220 Digital Microphone Module Schematic diagram of soundcard Feature header signal assignment Performance mmo ao SF Electrical architecture of the soundcard Introduction to Wolfson Audio Card for Raspberry Pi Raspberry Pi whilst being equipped with audio capability is limited in a number of ways The limitations are purposeful in order to keep Raspberry Pi at a low price point In terms of audio there are no ways to capture audio using Raspberry Pi alone and audio output is limited to two paths analogue via its onboard 3 5 mm stereo output jack and digital via its onboard HDMI output Whilst the HDMI output provides the potential for high quality rendering of audio depending on what HDMI devices are used to finally convert audio from its digital format to an analogue signal the audio quality from the analogue 3 5 mm stereo output jack is universally recognised as being of an acceptable quality level no more The most important limitation is Raspberry Pi s lack flexibility in terms of multiple typ
8. al audio data stream Read more here www element14 com wolfson lt name of file or forward to Wolfson URL gt d Schematic diagram If you are interested in knowing how the Wolfson Audio Card has been designed the schematic diagram is available to view as a pdf document on the element14 com website at the following address www element14 com wolfson lt name of file or forward to Wolfson URL gt Wav wolfsor elementiu e Feature header signal assignment Pin Name Type Power Description domain 1 5V Power Pin 5 0V 5V supply less than 300ma 2 3 3V Power Pin 3 3V 3 3V supply less than 300ma 3 AIF3LRCLK Digital in out 0 3 3V Audio interface 3 left right clock 4 AIF3TXDAT Digital out 0 3 3V Audio interface 3 TX digital audio data 5 AIF3RXDAT Digital in 0 3 3V Audio interface 3 RX digital audio data 6 AIF3BCLK Digital in out 0 3 3V Audio interface 3 bit clock 7 GND Power Pin 0 Digital ground 8 GND Power Pin 0 Digital ground 9 SCLK Digital in 0 3 3V Control Interface clock input 10 SDA Digital in out 0 3 3V Control Interface data input and output 11 PDMDAT Digital out 0 3 3V Digital speaker PDM data output 12 PDMCLK Digital out 0 3 3V Digital speaker PDM clock output 13 GND Power Pin 0 Digital ground 14 GND Power Pin 0 Digital ground 15 GPIO4 Digital in out 0 3 3V General purpose pin GPIO4 16 GPIO3 Digital in out 0 3 3V General purp
9. d indicator will light up on the Raspberry Pi indicating the main chip has started up and then a small green indicator will begin to flash indicating data is being read from written to the SD Card The TV monitor provided it s switched on of course will begin to show the Linux boot sequence 9 This 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 Notes on this section It is intended that ultimately drivers will be fully integrated in future OS downloads starting with Raspbian The All in One approach will then no longer be necessary Even though they are already included in the All in One package all the downloadable items required for the soundcard are available separately at www element14 com wolfson including the HD Audio tracks and the Use Case Scripts Once the system has booted up it is suggested that one complete reboot cycle is performed before attempting any of the next steps You may notice trace errors during boot up These are regarded as harmless and they will not appear on future releases VV 5 Wwolfsory elementiu Getting started with audio on your Wolfson Audio Card The Wolfson Audio Soundcard renders and captures high quality audio from a variety of sources It is designed to work with the Linux operating system and as such takes advantage of ALSA the Advanced
10. eaker connected to this card before playing back any audio tracks Wav Wolfson elementiu 7 Annexe a Datasheet of WM5102 audio CODEC The key technology that is used at the heart of the Wolfson Audio Card is an Audio Hub CODEC device The WM5102 is a highly integrated low power audio system that has been designed for use in smartphones tablets and other portable audio devices It combines wideband telephony voice processing with a flexible high performance audio hub CODEC and is capable of delivering HD audio If you d like to know more about this device take a look at it here www element14 com wolfson lt name of file or forward to Wolfson URL gt b Datasheet of WM8804 SPDIF receiver transmitter The WM8804 allows digital audio data to be transmitted and received to the audio card via the phono RCA jacks and works in partnership with the WM5102 You can read more about this device by checking out the following datasheet www element14 com wolfson lt name of file or forward to Wolfson URL gt c Datasheet of WM7220 Digital Microphone Module MEMS The WM7220 is a Digital Microphone Module DMIC that is based on MEMS technology MEMS or Micro Electrical Mechanical Systems are devices that combine small scale electronics on a silicon die together with a mechanical component that can interact with the physical environment In this case the mechanical element responds to acoustic pressure waves and converts them in to a digit
11. ect your audio card to digital amplifiers and receivers also known collectively as sinks using the phono RCA Cinch SPDIF output jack The Wolfson Audio Card can deliver audio in bit depths of up to 24 bit Make sure your sink can support resolutions this high Warnings Be very careful when setting the output gain and volume control on your amplifier especially if it is a powerful type Loudspeaker damage can easily occur if the volume is too high Connecting your audio card to a Line level sink You can connect your audio card to analogue amplifiers and receivers by using the green 3 5mm line output jack The use case scripts have been set up to provide a line out level that is not too high and should be suitable for most amplifiers and receivers Connecting your audio card to a Line level source Capturing audio using your Wolfson Audio Card is straightforward as well In the case of an analogue line level source simply connect your analogue source to the Audio Card by connecting to the red 3 5 mm input jack Then run the appropriate use case to set up the audio card routing and gains properly You can capture audio to a file by using the arecord command at a command prompt on Raspberry Pi The arecord command will allow you to flexibly capture live audio and saves it directly to Raspberry Pi s mass storage memory as an uncompressed audio file For example if you would like to capture audio from the line in jack first of all
12. es of input sources and outputs Wav Wolfson elementiu 2 Features This product designed by element14 and Wolfson Microelectronics in partnership addresses the above that by providing a rich set of high quality audio features as follows Features Analogue line level output Analogue line level input Digital stereo audio input SPDIF Digital stereo audio output SPDIF High quality headphone output with microphone facility for headphones with boom microphone Onboard stereo digital microphones Ability to play High Definition HD Audio Arrives bundled with five High Definition Audio files to demonstrate the systems capability Onboard power amplifier for directly driving loudspeakers Requires headers to be fitted Headphone Out Lineln LineOut MicIn lt 4 SPD IF In ii lt _ SPOF out Speaker Out L _ gt s T a Speaker Out R _ m s i lt lt AU Power In Expansion Header 2O CCOOOCCECK AAAA Digital Digital MEMS MEMS Microphone Microphone L DMIC R DMIC Diagram 1 Connections to and from the Wolfson Audio Card Wav Wolfson elementiu 3 Howto connect the Wolfson Audio Card to Raspberry Pi This Wolfson soundcard has been designed to plug in to Raspberry Pi simply and easily It is compatible with Raspberry Pi Models A and B Hardware Revision 2 0 boards which feature the 8
13. ion 1 2 Engineer DM Diagram 5 Power management architecture of the Wolfson audio card VV Wolfson microelectronics elementiu Revisions Revision Created Revision 1 00 28 Jan 2014 Initial publication 1 10 05 Mar 2014 Command error corrected Schematic diagrams updated
14. ose pin GPIO3 Table 3 GPIO signal definitions f Performance and Specification During the design process the board layout was optimised to ensure each of the Wolfson Microelectronics devices performed optimally providing users with an exceptional audio experience Measured performance of the board is as follows SPDIF Output Typical Parameter Description Value Units Connector Electrical output via phono connector Rout Output impedance Supported Sample Rates 32 48 96 192 44 1 88 2 176 4 192 Sample depth Max bit depth of samples Sample rate must be the same as TX if both are Notes enabled concurrently Wav wolfsor elementiu Typical Parameter Description Value Connector Electrical input via phono connector Rin Input impedance Supported Sample Rates 32 48 96 192 44 1 88 2 176 4 192 Sample depth Max bit depth of samples Notes Sample rate must be the same as RX if both are enabled concurrently Typical Parameter Description Conditions Value Units Connector Electrical output via 3 pole 3 5mm Socket Rout Output impedance Cload Max capacitive load on output Rload Vout Full scale output signal level Vnoise Noise Floor no signal applied A weighting filter THD Total Harmonic Distortion Notes _ Test conditions as follows unless otherwise noted 48kHz sample rate test signal 1kHz sine wave bandwidth measured 20Hz to 20kHz
15. pin audio GPIO connector known as P5 and located right next to the GPIO header as show below Diagram 2 Raspberry Pi with P5 connector outlined in red It uses innovative sprung connectors to connect with Raspberry Pi This avoids the need to solder an 8 pin header to your Raspberry Pi thus making installation quick and easy a Ensure the eight pads on connector P5 on Raspberry Pi are free of dirt and grease If necessary use a little degreaser such as a very small amount of detergent on a lightly dampened paper towel and wipe the eight pads clean Leave them to dry thoroughly b If necessary repeat the process with the sprung connectors on the soundcard c Locate the nylon pillar in the box contents screw it into the mounting hole shown in the image below and tighten Don t over tighten d Push the soundcard onto Raspberry Pi making sure the board is pressed all the way and that all eight pins have made contact with Raspberry Pi Wav Wolfson elementiu Diagram 3 The Audio Card must be secured to Raspberry Pi with the supplied pillar and screw set e Line up the nylon pillar on the Raspberry Pi with the mounting hole on the soundcard such that both holes are co axial Insert the other screw and tighten Don t over tighten f The soundcard is now properly installed onto your Raspberry Pi Notes on this section Please be aware that this soundcard is not compatible with accessory expanders such as the
16. r Raspberry Pi and perform a hard reboot issue a sudo halt switch of the power re apply power and allow to boot up Assuming all was well you system has now been configured to play audio Next start Music Player by double clicking on it on the desktop The programme will launch To select a file for playback it must first be added to the playlist Select Playlist gt Add To Playlist gt Add Files or Folders and you will be presented with a VV wolfson elementiu dialogue box where you can navigate to the location of your music files In the case of the bundled HD Audio tracks these are located in the Home directory Select the file s you want to play and then click on the Add button The files you added will now be available for playback in the Playlist Finally plug in your headphones in to the Headphone socket Now double click on the item you wish to play and Music Player will play the audio track to your headphones The scripts for playback are cumulative in nature So taking the above example into account where we have enabled playback to a headset if we then run the script to play audio to the line out jack as well with the following command Playback_to_Lineout sh lt Enter gt What happens is that audio playback is enabled for both headset and line out If that is not what you want and simply want to reset all the paths back to NO playback paths enabled then just run the following command first Rese
17. t and should use it but if not try PeaZip available at http peazip com In the case of PeaZip simply right click on the zip file and select Peazip gt Extract here When you have done this you get a single file called an Image File or img This is a snapshot of what needs to be written to the SD Card Next you need a tool to install the img file to the SD Card A popular tool is called Win32DiskImager and it is available at this address https launchpad net win32 image writer Simply download this program file and follow the instructions to install it on your Windows computer Follow the instructions provided with Win32DiskImager for writing the Operating System to your SD Card This process will require the SD Card to be inserted into a SD Card slot on your computer and for you to know where you saved the img file on your computer The write process itself can take some time WARNING Make sure you select the correct device to write the Operating System to Selecting the wrong destination could result in unrecoverable data loss Be careful and DOUBLE CHECK Win32DiskImager will tell you when this process has been completed and when it has remove the SD Card Now insert it into the SD card slot of your Raspberry Pi It is worth keeping the Operating System file on your computer for future rewrites to your SD Card just in case Now power up your Raspberry Pi and Wolfson Audio Card Wav Wolfson elementiu 8 The small re
18. t noise level no signal applied Vnoise settings for 63mVrms signal THD Total Harmonic Distortion 57mVrms Input Notes Test conditions as follows unless otherwise noted 48kHz sample rate test signal 1kHz sine wave and bandwidth measured is 20Hz to 20kHz Wav wolfsor elementiu Speaker Output Typical Parameter Description Conditions Value Units Connector Unpopulated 2 54mm pitch headers Rout Output impedance Rload Minimum Rload Power Out Max power output Vnoise Noise Floor no signal applied A weighting filter THD Total Harmonic Distortion 0 5W output Notes Test conditions as follows unless otherwise noted 48kHz sample rate test signal 1kHz sine wave bandwidth measured 20Hz to 20kHz Rload 8 Ohms SPKVDD 5V VV Wwolfsor elementi4 g Electrical architecture of the audio card Raspbi Pi Soundcard y oo vava Wolfson ANALOGUE IO 4 Pole Headset Jack 3 Pole Line Out Jack 3 Pole Line In Jack Speaker headers unpop 2x Wolfson Digital MIC Ld 49Pe89H Old9 SPKOUTLIR WM5102 SPDIF I O d 19PL H WOd 3 3V nominal I O Power Domain Level shift where interfacing with 1 8V signal Revision 1 2 Engineer DM Diagram 4 Audio architecture of the Wolfson audio card a VA Worson microelectronics Wall Plug Ld 49peaH Old9 WM5102 d 13PL H WOd WM8804 Revis
19. t_paths sh lt Enter gt Now select the single output that you want to play to Notes on this section 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 Whilst the onboard hardware CODEC is capable of handling multichannel audio Raspberry Pi is not Therefore the card will not allow the decoding of compressed multichannel audio via its SPDIF in connector The system will remember what the last used use case was After a reboot it will return to that one unless you choose another Wav Wolfson elementiu 6 Soundcard usage scenarios The Wolfson Audio Card is flexible with regards to how it can be connected to various types of input devices sources and output devices sinks If you d prefer to keep your audio in the digital domain the SPDIF digital audio connections allow this High quality analogue audio capture and playback is also made available with this card Connecting speakers to your Audio Card The Wolfson Pi 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 J
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