Adafruit I2s Stereo Decoder Uda1334a

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Adafruit I2S Stereo Decoder - UDA1334A
Created by lady ada

Last updated on 2017-11-27 10:57:29 PM UTC

Guide Contents
Guide Contents
Overview
Pinouts
Power Pins
I2S Pins
Audio Outputs
Optional Control Pins
Assembly
Installing Standard Headers
Raspberry Pi Wiring
Raspberry Pi Setup
Fast Install
Detailed Install
Update /etc/modprobe.d (if it exists)
Disable headphone audio (if it's set)
Create asound.conf file
Add Device Tree Overlay

Raspberry Pi Test
Speaker Tests!

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19

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21

Simple white noise speaker test
Simple WAV speaker test
Simple MP3 speaker test

Volume adjustment
Pi I2S Tweaks
Reducing popping

21
21
21

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23
23

Step 1

23

Add software volume control
Play Audio with PyGame
Install PyGame
Run Demo
Arduino Wiring & Test
Downloads
Files
Schematic & Fabrication Print

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Overview

This fully-featured UDA1334A I2S Stereo DAC breakout is a perfect match for any I2S-output audio interface. It's
affordable but sounds great! The NXP UDA1334A is a jack-of-all-I2S-trades: you can use 3.3V - 5V logic levels (a rarity),
and can process multiple different formats by setting two pins to high or low. The DAC will process data immediately,
and give you a clear, analog, stereo line level output. It's even cool with MCLK-less I2S interfaces such as the
Raspberry Pi (which it's ideal for) - a built in PLL will generate the proper clock from the incoming signal.

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For inputs, you can use classic I2S (the default) or 16-bit, 20-bit or 24-bit left justified data. You can set it up to take an
input system/master clock but we default-set it to just generate it for you, so you only need to connect Data In, Word
Select (Left/Right Clock) and Bit Clock lines. If you want, there's a mute pin and a de-emphasis filter you can turn on.

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We put in plenty of ferrite beads, a low-dropout regulator, and the recommended band-pass filter so you get a very
nice clean output. With a sine-wave generator we swept through 20-20KHz and saw no attenuation or distortion. Plug
into either the 3.5mm stereo headphone jack or the breadboard-friendly pads. We think you'll be pleased with this
DAC!

Each order comes with one I2S Stereo DAC breakout and some header you can solder on.

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Pinouts

The UDA1334A is an I2S amplifier - it does not use analog inputs, it only has digital audio input support! Don't confuse
I2S with I2C, I2S is a sound protocol whereas I2C is for small amounts of data.

Power Pins
The UDA1334A requires 3.3V power but can take 3-5V
level logic on nearly all pins.

You can provide 3-5V power on the VIN pin and GND
and the built in regulator will generate a nice clean 3.3V
supplier on 3VOut.

Use the quietest power supply for Vin, we do filter the
power supply, but the quieter the better!

I2S Pins

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Three pins are used for stereo I2S data in. These pins
are required!
These can be 3.3-5V logic
WSEL (Word Select or Left/Right Clock) - this is the
pin that tells the DAC when the data is for the left
channel and when its for the right channel
DIN (Data In) - This is the pin that has the actual
data coming in, both left and right data are sent on
this pin, the WSEL pin indicates when left or right
is being transmitted
BCLK (Bit Clock) - This is the pin that tells the
amplifier when to read data on the data pin.
MCLK is not required to use this DAC, if you have an
MCLK pin on your audio source, leave it disconnected.

Audio Outputs
The exciting part! This is where your line level audio
comes out. We put big 47uF blocking capacitors on the
output so you can connect this to any stereo system.
AGND is a clean analog ground signal that we
recommend using as your analog reference, you'll get a
cleaner signal.

Note that this DAC was intended for use with a separate
amplifier and is rated for a 3 KΩ load. However, we've
found you can plug in 32Ω headphones and the output
is current-limited so it won't damage the DAC but you
will get distortions. (Powered headphones won't have
this issue)

Optional Control Pins
There are some extra configuration pins if you want to use them. They are not required for 99% of usage with an
Arduino or Teensy or Raspberry Pi. But you never know! So they are there for you. PLL and SF0 are 3.3V logic only,
the other pins are 3-5V safe.
Most of the pins have to do with changing the setup from audio mode to video mode. If you happen to want videomode, for synchronizing with NTSC/PAL, check the datasheet - we haven't used it for that purpose.

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SCLK (Sys Clock) - Optional 27 MHz 'video mode'
ssytem clock input - by default we generate the
sysclock from the WS clock in 'audio mode' But
the UDA can also take a oscillator input on this pin
Mute - Setting this pin High will mute the output
De-Emphasis - In audio mode (which is the
default), can be used to add a de-emphasis filter.
In video mode, where the system clock is
generated from an oscillator, this is the clock
output.
PLL - sets the PLL mode, by default pulled low for
Audio. Can be pulled high or set to ~1.6V to set
PAL or NTSC video frequency

SF0 and SF1 are used to set the input data format. By
default both are pulled Low for I2S but you can change
them around for alternate formats.

See the back of the PCB for a quick reference

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Assembly

Installing Standard Headers
The shield comes with 0.1" standard header.
Break apart the 0.1" header into 6 and 9-pin long pieces
and slip the short ends into the holes in the board

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Make sure that all of the short parts of the header are
sticking through the two sets of pads on either side of
the board

Solder each one of the pins into the board to make a
secure connection

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That's it! Move on to next page for wiring information

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Raspberry Pi Wiring
if you have a Raspberry Pi and you want higher quality audio than the headphone jack can provide, I2S is a good
option! You only use 3 pins, and since its a pure-digital output, there can be less noise and interference.
This board works very well with boards that don't have audio like the Pi Zero and is the easiest way to get quality audio
out
This technique will work with any Raspberry Pi with the 2x20 connector. Older Pi 1's with a 2x13 connector do
not bring out the I2S pins as easily
Connect:
Amp Vin to Raspbery Pi 3V or 5V
Amp GND to Raspbery Pi GND
Amp DIN to Raspbery Pi #21
Amp BCLK to Raspbery Pi #18
Amp LRCLK to Raspbery Pi #19

Pi + UDA Fritzing
https://adafru.it/A9T

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Raspberry Pi Setup
At this time, Jessie Raspbery Pi kernel does not support mono audio out of the I2S interface, you can only
play stereo, so any mono audio files may need conversion to stereo!

Fast Install
Luckily its quite easy to install support for I2S DACs on Raspbian Jessie.
These instructions are totally cribbed from the PhatDAC instructions at the lovely folks at Pimoroni!
Run the following from your Raspberry Pi with Internet connectivity:
curl -sS https://raw.githubusercontent.com/adafruit/Raspberry-Pi-Installer-Scripts/master/i2samp.sh | bash

You will need to reboot once installed.

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You must reboot to enable the speaker hardware!
After rebooting, log back in and re-run the script again...It will ask you if you want to test the speaker. Say yes and
listen for audio to come out of your speakers...

In order to have volume control appear in Raspbian desktop or Retropie you must reboot a second time after doing
the speaker test, with sudo reboot
You can then go to the next page on testing and optimizing your setup. Skip the rest of this page on Detailed
Installation if the script worked for you!

Detailed Install
If, for some reason, you can't just run the script and you want to go through the install by hand - here's all the steps!

Update /etc/modprobe.d (if it exists)
Log into your Pi and get into a serial console (either via a console cable, the TV console, RXVT, or what have you)
Edit the raspi blacklist with
sudo nano /etc/modprobe.d/raspi-blacklist.conf

If the file is empty, just skip this step
However, if you see the following lines:

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blacklist i2c-bcm2708
blacklist snd-soc-pcm512x
blacklist snd-soc-wm8804

Update the lines by putting a # before each line

Save by typing Control-X Y 

Disable headphone audio (if it's set)
Edit the raspi modules list with
sudo nano /etc/modules

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If the file is empty, just skip this step
However, if you see the following line:
snd_bcm2835

Put a # in front of it

and save with Control-X Y 

Create asound.conf file
Edit the raspi modules list with
sudo nano /etc/asound.conf

This file ought to be blank!

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Copy and paste the following text into the file
pcm.speakerbonnet {
type hw card 0
}
pcm.dmixer {
type dmix
ipc_key 1024
ipc_perm 0666
slave {
pcm "speakerbonnet"
period_time 0
period_size 1024
buffer_size 8192
rate 44100
channels 2
}
}
ctl.dmixer {
type hw card 0
}
pcm.softvol {
type softvol
slave.pcm "dmixer"
control.name "PCM"
control.card 0
}
ctl.softvol {
type hw card 0
}
pcm.!default {
type
slave.pcm
}

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plug
"softvol"

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Save the file as usual

Add Device Tree Overlay
Edit your Pi configuration file with
sudo nano /boot/config.txt

And scroll down to the bottom. If you see a line that says: dtparam=audio=on

Disable it by putting a # in front.
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Then add:
dtoverlay=hifiberry-dac
dtoverlay=i2s-mmap

on the next line. Save the file.

Reboot your Pi with sudo reboot

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Raspberry Pi Test
Speaker Tests!
OK you can use whatever software you like to play audio but if you'd like to test the speaker output, here's some quick
commands that will let you verify your amp and speaker are working as they should!

Simple white noise speaker test
Run speaker-test -c2 to generate white noise out of the speaker, alternating left and right. Since the I2S amp merges
left and right channels, you'll hear continuous white noise

Simple WAV speaker test
Once you've got something coming out, try to play an audio file with speaker-test (for WAV files, not MP3)
speaker-test -c2 --test=wav -w /usr/share/sounds/alsa/Front_Center.wav

You'll hear audio coming from left and right alternating speakers

Simple MP3 speaker test
If you want to play a stream of music, you can try
sudo apt-get install -y mpg123
mpg123 http://ice1.somafm.com/u80s-128-mp3

If you want to play MP3's on command, check out this tutorial which covers how to set that up
At this time, Jessie Raspbery Pi kernel does not support mono audio out of the I2S interface, you can only play stereo,
so any mono audio files may need conversion to stereo!

Volume adjustment
Many programs like PyGame and Sonic Pi have volume control within the application. For other programs you can set
the volume using the command line tool called alsamixer. Just type alsamixer in and then use the up/down arrows to
set the volume. Press Escape once its set

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In Raspbian PIXEL you can set the volume using the menu item control. If it has an X through it, try restarting the Pi
(you have to restart twice after install to get PIXEL to recognize the volume control

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Pi I2S Tweaks
Reducing popping
For people who followed our original installation instructions with the simple alsa config, they may find that the I2S
audio pops when playing new audio.
The workaround is to use a software mixer to output a fixed sample rate to the I2S device so the bit clock does not
change. I use ALSA so I configured dmixer and I no longer have any pops or clicks. Note that the RaspPi I2S driver
does not support dmixer by default and you must follow these instructions provided to add it. Continue on for step-bystep on how to enable it!

Step 1
Start by modify /boot/config.txt to add dtoverlay=i2s-mmap
Run sudo nano /boot/config.txt and add the text to the bottom like so:

Save and exit.
Then change /etc/asound.conf to:

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pcm.speakerbonnet {
type hw card 0
}
pcm.!default {
type plug
slave.pcm "dmixer"
}
pcm.dmixer {
type dmix
ipc_key 1024
ipc_perm 0666
slave {
pcm "speakerbonnet"
period_time 0
period_size 1024
buffer_size 8192
rate 44100
channels 2
}
}
ctl.dmixer {
type hw card 0
}

By running sudo nano /etc/asound.conf
This creates a PCM device called speakerbonnet which is connected to the hardware I2S device. Then we make a
new 'dmix' device ( type dmix ) called pcm.dmixer . We give it a unique Inter Process Communication key ( ipc_key 1024 )
and permissions that are world-read-writeable (ipc_perm 0666 ) The mixer will control the hardware pcm device
speakerbonnet (pcm "speakerbonnet") and has a buffer set up so its nice and fast. The communication buffer is set up
so there's no delays ( period_time 0 , period_size 1024 and buffer_size 8192 work well). The default mixed rate is 44.1khz
stereo ( rate 44100 channels 2 )
Finally we set up a control interface but it ended up working best to just put in the hardware device here - ctl.dmixer {
type hw card 0 }

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Save and exit. Then reboot the Pi to enable the mixer. Also, while it will greatly reduce popping, you still may get one
once in a while - especially when first playing audio!

Add software volume control
The basic I2S chipset used here does not have software control built in. So we have to 'trick' the Pi into creating a
software volume control. Luckily, its not hard once you know how to do it.
Create a new audio config file in ~/.asoundrc with nano ~/.asoundrc and inside put the following text:

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pcm.speakerbonnet {
type hw card 0
}
pcm.dmixer {
type dmix
ipc_key 1024
ipc_perm 0666
slave {
pcm "speakerbonnet"
period_time 0
period_size 1024
buffer_size 8192
rate 44100
channels 2
}
}
ctl.dmixer {
type hw card 0
}
pcm.softvol {
type softvol
slave.pcm "dmixer"
control.name "PCM"
control.card 0
}
ctl.softvol {
type hw card 0
}
pcm.!default {
type
slave.pcm
}

plug
"softvol"

This assumes you set up the dmixer for no-popping above!

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Save and exit
Now, here's the trick, you have to reboot, then play some audio through alsa, then reboot to get the alsamixer to sync
up right:
speaker-test -c2 --test=wav -w /usr/share/sounds/alsa/Front_Center.wav

Then you can type alsamixer to control the volume with the 'classic' alsa mixing interface

Just press the up and down arrows to set the volume, and ESC to quit

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Play Audio with PyGame
You can use mpg123 for basic testing but it's a little clumsy for use where you want to dynamically change the volume
or have an interactive program. For more powerful audio playback we suggest using PyGame to playback a variety of
audio formats (MP3 included!)

Install PyGame
Start by installing pygame support, you'll need to open up a console on your Pi with network access and run:
sudo apt-get install python-pygame

Next, download this pygame example zip to your Pi

Click to download PyGame example code &
sample mp3s
https://adafru.it/wbp
On the command line, run
wget https://cdn-learn.adafruit.com/assets/assets/000/041/506/original/pygame_example.zip
unzip pygame_example.zip

Run Demo
Inside the zip is an example called pygameMP3.py
This example will playback all MP3's within the script's folder. To demonstrate that you can also adjust the volume
within pygame, the second argument is the volume for playback. Specify a volume to playback with a command line
argument between 0.0 and 1.0
For example here is how to play at 75% volume:
python pygameMP3.py 0.75

Here's the code if you have your own mp3s!

''' pg_midi_sound101.py
play midi music files (also mp3 files) using pygame
tested with Python273/331 and pygame192 by vegaseat
'''
#code modified by James DeVito from here: https://www.daniweb.com/programming/software-development/code/454835/let-py

#!/usr/bin/python
import
import
import
import

sys
pygame as pg
os
time

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def play_music(music_file):
'''
stream music with mixer.music module in blocking manner
this will stream the sound from disk while playing
'''
clock = pg.time.Clock()
try:
pg.mixer.music.load(music_file)
print("Music file {} loaded!".format(music_file))
except pygame.error:
print("File {} not found! {}".format(music_file, pg.get_error()))
return
pg.mixer.music.play()
# If you want to fade in the audio...
# for x in range(0,100):
#
pg.mixer.music.set_volume(float(x)/100.0)
#
time.sleep(.0075)
# # check if playback has finished
while pg.mixer.music.get_busy():
clock.tick(30)

freq = 44100
# audio CD quality
bitsize = -16
# unsigned 16 bit
channels = 2
# 1 is mono, 2 is stereo
buffer = 2048
# number of samples (experiment to get right sound)
pg.mixer.init(freq, bitsize, channels, buffer)

if len(sys.argv) > 1:
try:
user_volume = float(sys.argv[1])
except ValueError:
print "Volume argument invalid. Please use a float (0.0 - 1.0)"
pg.mixer.music.fadeout(1000)
pg.mixer.music.stop()
raise SystemExit
print("Playing at volume: " + str(user_volume)+ "\n")
pg.mixer.music.set_volume(user_volume)
mp3s = []
for file in os.listdir("."):
if file.endswith(".mp3"):
mp3s.append(file)
print mp3s
for x in mp3s:
try:
play_music(x)
time.sleep(.25)
except KeyboardInterrupt:
# if user hits Ctrl/C then exit
# (works only in console mode)
pg.mixer.music.fadeout(1000)
pg.mixer.music.stop()
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pg.mixer.music.stop()
raise SystemExit
else:
print("Please specify volume as a float! (0.0 - 1.0)")

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Arduino Wiring & Test

The classic ATmega328P-based Arduino's like the UNO and Metro 328 don't have I2S interfaces, so you can't use this
breakout with them
But the newer ATSAMD21-based boards like the Zero, Metro M0, Feather M0 can! (Note, Gemma M0 & Trinket M0 do
not have I2S pins available).
You may want to check your board documentation to determine where the I2S interface is. We'll use the Metro M0
pinout:
LRCLK / WSEL on Digital #0
BCLK on Digital #1
DATA IN on Digital #9
Then power from 3.3V + Ground as usual:

We can then run this demo which will generate a sine wave on both left and right channels. Try tweaking the sample
rate, amplitude and frequency, see how the quality and volume changes!

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/*
This example generates a sine wave based tone at a specified frequency
and sample rate. Then outputs the data using the I2S interface.
Public Domain
*/
#include 
#define FREQUENCY
440
#define AMPLITUDE 10000
#define SAMPLERATE 44100

// frequency of sine wave in Hz
// amplitude of sine wave
// sample rate in Hz

int16_t sinetable[SAMPLERATE / FREQUENCY];
uint32_t sample = 0;
#define PI 3.14159265
void setup() {
Serial.begin(115200);
Serial.println("I2S sine wave tone");
// start I2S at the sample rate with 16-bits per sample
if (!I2S.begin(I2S_PHILIPS_MODE, SAMPLERATE, 16)) {
Serial.println("Failed to initialize I2S!");
while (1); // do nothing
}
// fill in sine wave table
for (uint16_t s=0; s < (SAMPLERATE / FREQUENCY); s++) {
sinetable[s] = sin(2.0 * PI * s / (SAMPLERATE/FREQUENCY)) * AMPLITUDE;
}
}

void loop() {
if (sample == (SAMPLERATE / FREQUENCY)) {
sample = 0;
}
// write the same sample twice, once for left and once for the right channel
I2S.write((int16_t) sinetable[sample]); // We'll just have same tone on both!
I2S.write((int16_t) sinetable[sample]);
// increment the counter for the next sample in the sine wave table
sample++;
}

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Downloads
Files
EagleCAD PCB Files
Fritzing object in Adafruit Fritzing library
UDA1334A Datasheet

Schematic & Fabrication Print

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© Adafruit Industries

Last Updated: 2017-11-27 10:57:29 PM UTC

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