PLEASE NOTE: This article is obsolete or related to a discontinued product.

Daisy 16 Audio Adapter

Audio interface for FOX Board G20

This module is designed for the FOX Board G20 and is not compatible with the Aria and Arietta G25 boards.

The audio codec used is the WM8731, is low power stereo codec with an integrated headphone driver, stereo line-out, stereo line-in and mono microphone level audio inputs.

WM8731 Codecs is supported by the Linux kernel and works with alsa drivers.

Daisy16

Dimension: 40x40mm

WM8731 Codec Features

Stereo 24-bit, multi-bit sigma delta ADCs and DACs are used with oversampling digital interpolation and decimation filters.
Highly Efficient Headphone Driver
Audio Performance : ADC SNR 90dB at 3.3V , DAC SNR 100dB at 3.3V
Low Power : Playback only 22mW
Selectable ADC High Pass Filter
Microphone Input and Electret Bias with Side Tone Mixer

Communication between Fox Board and Codecs

Audio Interface

PB16	PB17	PB18	PB19	PB21
TK0	TF0	TD0	RD0	RF0

Control Interface

PA23	PA24
SDA	SCL

The communication between the Fox Board and the Codec is done by SSC (Synchronous Serial Controller) for the audio interface (Daisy D5 to J2) and TWI (I2C) for control interface (Daisy D6 to J1).
PB31 (PCK1) provides Master Clock to codec.
RK0 is not used so PB20 control the Play-LED

Add audio support to the Linux Kernel for the Daisy16

WM8731 codecs is supported in the linux kernel but to be used with the Daisy16 needs some changes. You must apply an additional patch.

Precompiled Kernel Image

Files to store in the first FAT16 partition:

Kernel 2.6.35.4 image daisy16_2.6.35.4_uImage (MD5:daf39e532a84e1a29f764efbe31a4e05)
Kernel 2.6.38 image daisy16_2.6.38_uImage (MD5:74ba68dd909db3edb2ab73bff9707250)

How to apply Madefree patch and compile kernel

Linux kernel 2.6.35.4

Download the kernel sources and apply Acme Systems patch:

wget http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.35.4.tar.bz2
tar -xjvf linux-2.6.35.4.tar.bz2
cd linux-2.6.35.4
wget http://www.acmesystems.it/foxg20/download/kernel/0003-Acme-Systems-board-files.patch
patch -p1 < 0003-Acme-Systems-board-files.patch
wget http://www.acmesystems.it/foxg20/download/kernel/makefile

Download the Madefree Patch daisy16_26354.tar.gz (MD5:8e5ede6d218e34574c71cfdbcb880dfc)
Apply the patch:

tar -xzvf daisy16_26354.tar.gz
patch -p1 < daisy16_26354/daisy16_26354.patch

Then copy the .config to use the last Madefree factory default configuration files:

cp daisy16_26354/daisy16_26354.config .config

Configuring kernel (if you need):

make menuconfig

Building kernel:

make

Linux kernel 2.6.38

Download the kernel sources:

wget http://www.kernel.org/pub/linux/kernel/v2.6/linux-2.6.38.tar.bz2
tar -xjvf linux-2.6.38.tar.bz2
cd linux-2.6.38
wget http://foxg20.acmesystems.it/download/kernel_2.6.38/makefile

Download the Madefree Patch daisy16_2638.tar.gz (MD5:c9f75aca53b6858c3c82edd5a497b718)
Apply the patch:

tar -xzvf daisy16_2638.tar.gz
patch -p1 < daisy16_2638/daisy16_2638.patch

Then copy the .config to use the last Madefree factory default configuration files:

cp daisy16_2638/daisy16_2638.config .config

Configuring kernel (if you need):

make menuconfig

Building kernel:

make

Check the functionalities

Check dmesg after boot:

...
ssc ssc.0: Atmel SSC device at 0xc48a0000 (irq 14)
...
netusG20_wm8731 : daisy16: wm8731__init() called
asoc: wm8731-hifi <-> atmel-ssc-dai.0 mapping ok
ALSA device list:
  #0: DAISY16
...

Install alsa-utils:

apt-get install alsa-utils

Run alsamixer:

alsamixer -V all

Configure alsa like this:

Launch recording for 5sec. stereo wav acquisition and play what you recorded:

arecord -d 5 -v -v -Dhw:0,0 -f cd record_line_in.wav
aplay record_line_in.wav

Play your music library

A great console music player is cmus.

apt-get install cmus
cmus

Change output plugin (from cmus command line)

:set output_plugin=ao

Cmus has a syntax very similar to vim:

:add 'directory_audio'  # add audio file to playlist
:q  # exit to cmus
z  # previous
x  # play
c  # pause
v  # stop
b  # next
^L # refresh
n  # search-next
r  # toggle repeat
1  # view tree
2  # view sorted
3  # view playlist
4  # view queue
5  # view browser
6  # view filters
7  # view settings
+  # vol +10%
-  # vol -10%

Playing in remote access

You can use Music Player Daemon (MPD) to allow remote access for playing audio files (Ogg-Vorbis, FLAC, MP3, Wave, and AIFF), streams (Ogg-Vorbis, MP3) and managing playlists.