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.

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.

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.

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

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 video-mode, for synchronizing with NTSC/PAL, check the datasheet - we haven't used it for that purpose.

  • 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

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

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

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

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

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.

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:

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 <return>

Disable headphone audio (if it's set)

Edit the raspi modules list with

sudo nano /etc/modules

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 <return>

Create asound.conf file

Edit the raspi modules list with

sudo nano /etc/asound.conf

This file ought to be blank!

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             plug
    slave.pcm       "softvol"
}

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.

Then add:
dtoverlay=hifiberry-dac
dtoverlay=i2s-mmap

on the next line. Save the file.

Reboot your Pi with sudo reboot

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

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

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-by-step on how to enable it!

Step 1

Start by modify /boot/config.txt to adddtoverlay=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:

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 }

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:

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             plug
    slave.pcm       "softvol"
}
This assumes you set up the dmixer for no-popping above!

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

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

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-pygame-play-your-midi-or-mp3-files


#!/usr/bin/python

import sys
import pygame as pg
import os
import time


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()
            raise SystemExit
else:
    print("Please specify volume as a float! (0.0 - 1.0)")

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!

/*
 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 <I2S.h>

#define FREQUENCY    440  // frequency of sine wave in Hz
#define AMPLITUDE  10000  // amplitude of sine wave
#define SAMPLERATE 44100  // 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++;
}

Downloads