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Migrate the sound page from the wiki
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‎docs/tutorials/using-ev3-speaker.md‎

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---
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title: Using the EV3 Speaker
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group: hardware-standard
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---
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* Table of Contents
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{:toc}
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## Introduction
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The EV3 uses pulse-width modulation (PWM) to drive an amplifier that produces the
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sounds that you hear through the speaker. It has two modes of operation. The first,
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we call **Tone** mode (aka **Beep** mode). In Tone mode, the PWM is set to a
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frequency in the [audible range][1]. The sound you hear is a square wave.
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The second mode is called **PCM Playback** mode. In this mode, the PWM is operated
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at a higher frequency. The high frequencies are (mostly) filtered out and we are
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able to reproduce a recorded sound.
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[1]: https://en.wikipedia.org/wiki/Audio_frequency
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## Tone Mode
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There are a couple of ways to control the speaker in Tone mode. Also worth an
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honorable mention: if you plug a USB keyboard into the EV3 and press
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<kbd>CTRL</kbd>+<kbd>G</kbd>, it will beep!
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### beep command
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The [beep man page][2] has all you need to know.
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[2]: https://manpages.debian.org/jessie/beep/beep.1.en.html
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Examples:
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```bash
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$ beep # 440 Hz for 200 ms
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$ beep -f 200 -l 500 # 220 Hz for 500 ms
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$ beep -f 262 -l 180 -d 20 -r 2 \
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-n -f 392 -l 180 -d 20 -r 2 \
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-n -f 440 -l 180 -d 20 -r 2 \
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-n -f 392 -l 380 -d 20 \
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-n -f 349 -l 180 -d 20 -r 2 \
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-n -f 330 -l 180 -d 20 -r 2 \
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-n -f 294 -l 180 -d 20 -r 2 \
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-n -f 262 -l 400 # twinkle twinkle little star
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```
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### tone sysfs Attribute
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TODO: using the `tone` attribute is not really recommended. This needs to be
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updated with an example on how to use the Linux input subsystem instead.
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We have also provided a way to play tones directly using the sysfs attribute
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`/sys/devices/platform/snd-legoev3/tone`.
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Example:
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```bash
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$ cd /sys/devices/platform/snd-legoev3
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$ echo 1000 10000 > tone # play a 1 KHz tone for 10 seconds
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$ echo 440 > tone # play a 440 Hz tone (endless mode)
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$ echo 0 > tone # stop the tone
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```
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## PCM Playback Mode
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PCM playback is implemented as an ALSA driver. This means that you can use just
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about any Linux program out there that can play sound. We have found the best
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compromise between sound quality and CPU usage is to use a sample rate 22050 Hz.
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16000 Hz sounds pretty good too. Of course the speaker is so small, the sound
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quality is just not going to be "high quality" no matter what.
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Example: Playing back a .wav file using `aplay`.
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```bash
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$ aplay my-file.wav
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Playing WAVE 'my-file.wav' : Signed 16 bit Little Endian, Rate 22050 Hz, Mono
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```
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{% include /style/icon.html type="info" %}
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You must be a member of the `audio` group in order to use the sound driver.
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{: .alert .alert-info}
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## Volume control
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Again, there are a number of ways to do this. Currently, there is only a master
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volume control that controls both Tone mode and PCM Playback mode.
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### amixer Command
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Documentation:
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* [man page](https://manpages.debian.org/jessie/alsa-utils/amixer.1.en.html)
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Example:
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```bash
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$ amixer get Playback,0 # get current volume
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Simple mixer control 'Playback',0
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Capabilities: volume volume-joined penum
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Playback channels: Mono
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Capture channels: Mono
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Limits: 0 - 256
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Mono: 255 [100%]
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$ amixer set Playback,0 50% # set volume to 50%
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Simple mixer control 'Playback',0
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Capabilities: volume volume-joined penum
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Playback channels: Mono
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Capture channels: Mono
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Limits: 0 - 256
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Mono: 128 [50%]
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```
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### alsamixer Command
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Graphical volume controls.
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```
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┌───────────────────────────── AlsaMixer v1.0.25 ──────────────────────────────┐
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│ Card: LEGO Mindstorms EV3 speaker F1: Help │
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│ Chip: F2: System information │
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│ View: F3:[Playback] F4: Capture F5: All F6: Select sound card │
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│ Item: Playback Esc: Exit │
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│ │
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│ ┌──┐ │
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│ │ │ │
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│ │ │ │
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│ │ │ │
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│ │ │ │
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│ │ │ │
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│ │ │ │
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│ │ │ │
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│ │▒▒│ │
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│ │▒▒│ │
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│ │▒▒│ │
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│ │▒▒│ │
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│ │▒▒│ │
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│ └──┘ │
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│ 40 │
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│ <Playback> │
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│ │
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└──────────────────────────────────────────────────────────────────────────────┘
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```
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## More Fun!
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### Text-To-Speech
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```bash
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$ espeak "hello, I am an EV3.
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> I like to talk because I am a robot.
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> Did you know that robots like to make sounds?
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> Beep. Boop. Dit. Dit. Meep.
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> I am just such a chatterbox." --stdout | aplay
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Playing WAVE 'stdin' : Signed 16 bit Little Endian, Rate 22050 Hz, Mono
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```
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{% include /style/begin-panel.html type="info" heading="Tip" %}
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Add a function like this to your `~/.bashrc` file.
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```bash
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speak(){
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espeak -a 200 -s 130 -v la --stdout "$@" | aplay --quiet
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}
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```
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Then you can simply use:
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```bash
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$ speak "Thanks to GeekDude for this idea!" # @G33kDude
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```
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{% include /style/end-panel.html %}
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### MP3 player
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```bash
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$ sudo apt-get update
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$ sudo apt-get install mpg123 # or mpg321
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...
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$ mpg123 /home/ev3dev/Music/01-The\ Jumpin\'\ Jive.mp3
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High Performance MPEG 1.0/2.0/2.5 Audio Player for Layers 1, 2 and 3
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version 1.14.4; written and copyright by Michael Hipp and others
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free software (LGPL/GPL) without any warranty but with best wishes
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Directory: /home/ev3dev/Music/
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Playing MPEG stream 1 of 1: 01-The Jumpin' Jive.mp3 ...
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MPEG 1.0 layer III, 128 kbit/s, 44100 Hz joint-stereo
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Title: The Jumpin' Jive Artist: Cab Calloway
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Comment: Album: Minnie the Moocher [Universal]
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Year: 1989 Genre: Swing
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```

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