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eramons committed Mar 7, 2024
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16 changes: 9 additions & 7 deletions content/post/raspi_radio.md
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_Build an internet radio with an old Raspberry Pi 3 leveraging the Music Player Daemon (mpd)._
_Build an internet radio with an old Raspberry Pi 3 and the Music Player Daemon (mpd)._

The ultimative goal is to refurbish a beautiful old radio from the 1930's.

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```
For the first test, I connected the HDMI output of the raspberry Pi to the HDMI input of our living-room home cinema system. The speakers of the system are pasive speakers, but the system has already an amplifier and a DAC (Digital Analog Converter) built on it.

To test later directly directly with other passive speakers, I would need an analog audio output and an amplifier: the HiFiBerry Miniamp. At the moment of this first test it was already ordered but still on its way to me and was supposed to arrive in a couple of days.
_I would test later connecting passive speakers directly. For that, I would need analog audio output and therefore a DAC and an amplifier: the HiFiBerry Miniamp. At the moment of this first test it was already ordered but still on its way, it was supposed to arrive in a couple of days._

I would like the music to keep playing between reboots:

Expand All @@ -187,7 +187,7 @@ After reboot, radio paradise started playing out of the home cinema speakers :)
For a bit later, instead of using mpc as the client, there are interesting possibilities:

* Use an android mpc client, to play music remotely
* In order to build custom physical controls, use the GPIO interface of the Raspberry Pi and translate the microcontroller commands into mpc calls, using python code and the corresponding python-mpd and _rpi.gpio_ libraries
* In order to build custom physical controls, use the GPIO interface of the Raspberry Pi and translate the microcontroller commands into mpc calls, using python code and the corresponding _python-mpd_ and _rpi.gpio_ libraries

I'll tell more about the physical controls and the GPIO interface in the upcoming post, since it will be the basis for the refurbishing of the vintage radio I mentioned at the beginning.

Expand Down Expand Up @@ -229,7 +229,9 @@ And then, on a sunny Thursday morning, my miniamp was delivered :D

![Miniamp](/techblog/img/vintage_radio/miniamp.jpg)

Connecting it to the raspberry pi was straighforward, just connect the small board over the GPIO pins. A thought arised: to use the GPIO interface later for switching on/off and controling the volume, I would need some kind of extension so I could still use the GPIO pins, which were now all blocked after connecting the miniamp. That should be possible, since only some of the pins are effectively used by miniamp.
Connecting it to the raspberry pi was straighforward, just connect the small board over the GPIO pins.

_A thought arised: to use the GPIO interface later for switching on/off and controling the volume, I would need some kind of extension so I could still use the GPIO pins, which were now all blocked after connecting the miniamp. That should be possible, since only some of the pins are effectively used by miniamp._

I followed the instructions in the hifiberry documentation to make the raspi recognise the hifiberry sound card. It wasn't much, just modifying a couple of config files, as described next.

Expand Down Expand Up @@ -280,11 +282,11 @@ systemctl restart mpd

And now? I needed some passive speakers to test if the little hifiberry amplifier was working.

I found some in my cellar - which belonged to an old home sound system - so I connected two of them to the miniamp using their cables, following the polarity I found in the miniamp documentation (references below). Black is minus and red is plus, as far as I know:
I got two small passive speakers with an impedance of 4 Ohm and 3 watt of power. Then I connected them to the miniamp with thin copper wires, following the polarity I found in the miniamp documentation (references below) and taking into consideration that black is minus and red is plus.

![Connection](/techblog/img/vintage_radio/connection.jpg)
![Raspi](/techblog/img/vintage_radio/raspi_radio.jpg)

Surprisingly enough, it worked at the first try, the music was playing, much loudly as expected :D
Surprisingly enough, it worked at the first try, the music was playing, much loudlier as expected :D

Now it's time to play a little around with the mpc client. First things first - adjust the volume before the neighbours come ringing at the door:
```
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25 changes: 13 additions & 12 deletions docs/post/raspi_radio/index.html
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<meta name="description" content="Build an internet radio with an old Raspberry Pi 3 leveraging the Music Player Daemon (mpd).
<meta name="description" content="Build an internet radio with an old Raspberry Pi 3 and the Music Player Daemon (mpd).
The ultimative goal is to refurbish a beautiful old radio from the 1930&rsquo;s.
I intend to tell more about this radio in an upcoming post, but - spoiler alert - I can already tell that the original radio mechanism is probably beyond repair. The most feasible way seems to build a new device inside the old radio and bind the original buttons to the new platform, to control things like switching the power on and adjusting the sound volume.">

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<meta property="og:title" content="Raspberry Pi Internet Radio" />
<meta property="og:description" content="Build an internet radio with an old Raspberry Pi 3 leveraging the Music Player Daemon (mpd).
<meta property="og:description" content="Build an internet radio with an old Raspberry Pi 3 and the Music Player Daemon (mpd).
The ultimative goal is to refurbish a beautiful old radio from the 1930&rsquo;s.
I intend to tell more about this radio in an upcoming post, but - spoiler alert - I can already tell that the original radio mechanism is probably beyond repair. The most feasible way seems to build a new device inside the old radio and bind the original buttons to the new platform, to control things like switching the power on and adjusting the sound volume." />
<meta property="og:type" content="article" />
Expand All @@ -43,7 +43,7 @@

<meta name="twitter:card" content="summary"/>
<meta name="twitter:title" content="Raspberry Pi Internet Radio"/>
<meta name="twitter:description" content="Build an internet radio with an old Raspberry Pi 3 leveraging the Music Player Daemon (mpd).
<meta name="twitter:description" content="Build an internet radio with an old Raspberry Pi 3 and the Music Player Daemon (mpd).
The ultimative goal is to refurbish a beautiful old radio from the 1930&rsquo;s.
I intend to tell more about this radio in an upcoming post, but - spoiler alert - I can already tell that the original radio mechanism is probably beyond repair. The most feasible way seems to build a new device inside the old radio and bind the original buttons to the new platform, to control things like switching the power on and adjusting the sound volume."/>

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"headline": "Raspberry Pi Internet Radio",
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"description": "Build an internet radio with an old Raspberry Pi 3 leveraging the Music Player Daemon (mpd).\nThe ultimative goal is to refurbish a beautiful old radio from the 1930\u0026rsquo;s.\nI intend to tell more about this radio in an upcoming post, but - spoiler alert - I can already tell that the original radio mechanism is probably beyond repair. The most feasible way seems to build a new device inside the old radio and bind the original buttons to the new platform, to control things like switching the power on and adjusting the sound volume.",
"description": "Build an internet radio with an old Raspberry Pi 3 and the Music Player Daemon (mpd).\nThe ultimative goal is to refurbish a beautiful old radio from the 1930\u0026rsquo;s.\nI intend to tell more about this radio in an upcoming post, but - spoiler alert - I can already tell that the original radio mechanism is probably beyond repair. The most feasible way seems to build a new device inside the old radio and bind the original buttons to the new platform, to control things like switching the power on and adjusting the sound volume.",
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Expand All @@ -112,7 +112,7 @@
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"url" : "https:\/\/eramons.github.io\/techblog\/post\/raspi_radio\/",
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Expand Down Expand Up @@ -263,7 +263,7 @@ <h1>Raspberry Pi Internet Radio</h1>



<p><em>Build an internet radio with an old Raspberry Pi 3 leveraging the Music Player Daemon (mpd).</em></p>
<p><em>Build an internet radio with an old Raspberry Pi 3 and the Music Player Daemon (mpd).</em></p>
<p>The ultimative goal is to refurbish a beautiful old radio from the 1930&rsquo;s.</p>
<p>I intend to tell more about this radio in an upcoming post, but - spoiler alert - I can already tell that the original radio mechanism is probably beyond repair. The most feasible way seems to build a new device inside the old radio and bind the original buttons to the new platform, to control things like switching the power on and adjusting the sound volume.</p>
<p>At the time of this writing I don&rsquo;t have everything figured out yet. However, since all things have a beginning, I&rsquo;ll start with the part I&rsquo;m more at ease at, that&rsquo;s the software side of things. My first goal will be to build an internet radio with an old Raspberry Pi 3 and a HiFiBerry amplifier, leveraging the Music Player Daemon.</p>
Expand Down Expand Up @@ -365,7 +365,7 @@ <h1>Raspberry Pi Internet Radio</h1>
<pre tabindex="0"><code>mpc add http://stream-uk1.radioparadise.com/mp3-128
mpc play
</code></pre><p>For the first test, I connected the HDMI output of the raspberry Pi to the HDMI input of our living-room home cinema system. The speakers of the system are pasive speakers, but the system has already an amplifier and a DAC (Digital Analog Converter) built on it.</p>
<p>To test later directly directly with other passive speakers, I would need an analog audio output and an amplifier: the HiFiBerry Miniamp. At the moment of this first test it was already ordered but still on its way to me and was supposed to arrive in a couple of days.</p>
<p><em>I would test later connecting passive speakers directly. For that, I would need analog audio output and therefore a DAC and an amplifier: the HiFiBerry Miniamp. At the moment of this first test it was already ordered but still on its way, it was supposed to arrive in a couple of days.</em></p>
<p>I would like the music to keep playing between reboots:</p>
<ul>
<li>Since the mpd daemon service is enabled, it will start automatically</li>
Expand All @@ -378,7 +378,7 @@ <h1>Raspberry Pi Internet Radio</h1>
<p>For a bit later, instead of using mpc as the client, there are interesting possibilities:</p>
<ul>
<li>Use an android mpc client, to play music remotely</li>
<li>In order to build custom physical controls, use the GPIO interface of the Raspberry Pi and translate the microcontroller commands into mpc calls, using python code and the corresponding python-mpd and <em>rpi.gpio</em> libraries</li>
<li>In order to build custom physical controls, use the GPIO interface of the Raspberry Pi and translate the microcontroller commands into mpc calls, using python code and the corresponding <em>python-mpd</em> and <em>rpi.gpio</em> libraries</li>
</ul>
<p>I&rsquo;ll tell more about the physical controls and the GPIO interface in the upcoming post, since it will be the basis for the refurbishing of the vintage radio I mentioned at the beginning.</p>
<div class="gblog-post__anchorwrap"><h3 id="6-understanding-sound-cards-and-sound-devices">6. Understanding sound cards and sound devices<a data-clipboard-text="https://eramons.github.io/techblog/post/raspi_radio/#6-understanding-sound-cards-and-sound-devices" class="gblog-post__anchor gblog-post__anchor--right clip" aria-label="Anchor 6. Understanding sound cards and sound devices" href="#6-understanding-sound-cards-and-sound-devices"><svg class="icon link"><use xlink:href="#link"></use></svg></a></h3></div>
Expand Down Expand Up @@ -407,7 +407,8 @@ <h1>Raspberry Pi Internet Radio</h1>
<div class="gblog-post__anchorwrap"><h3 id="7-hifiberry-miniamp">7. HiFiBerry MiniAmp<a data-clipboard-text="https://eramons.github.io/techblog/post/raspi_radio/#7-hifiberry-miniamp" class="gblog-post__anchor gblog-post__anchor--right clip" aria-label="Anchor 7. HiFiBerry MiniAmp" href="#7-hifiberry-miniamp"><svg class="icon link"><use xlink:href="#link"></use></svg></a></h3></div>
<p>And then, on a sunny Thursday morning, my miniamp was delivered :D</p>
<p><img src="/techblog/img/vintage_radio/miniamp.jpg" alt="Miniamp"></p>
<p>Connecting it to the raspberry pi was straighforward, just connect the small board over the GPIO pins. A thought arised: to use the GPIO interface later for switching on/off and controling the volume, I would need some kind of extension so I could still use the GPIO pins, which were now all blocked after connecting the miniamp. That should be possible, since only some of the pins are effectively used by miniamp.</p>
<p>Connecting it to the raspberry pi was straighforward, just connect the small board over the GPIO pins.</p>
<p><em>A thought arised: to use the GPIO interface later for switching on/off and controling the volume, I would need some kind of extension so I could still use the GPIO pins, which were now all blocked after connecting the miniamp. That should be possible, since only some of the pins are effectively used by miniamp.</em></p>
<p>I followed the instructions in the hifiberry documentation to make the raspi recognise the hifiberry sound card. It wasn&rsquo;t much, just modifying a couple of config files, as described next.</p>
<p>Apparently, only the hifiberry sound card must be enabled. To deactivate any other audio output, edit <em>/boot/config.txt</em> changing the following line:</p>
<pre tabindex="0"><code>dtoverlay=vc4-kms-v3d,noaudio
Expand Down Expand Up @@ -443,9 +444,9 @@ <h1>Raspberry Pi Internet Radio</h1>
<pre tabindex="0"><code>systemctl restart mpd
</code></pre><div class="gblog-post__anchorwrap"><h3 id="8-passive-speakers">8. Passive speakers<a data-clipboard-text="https://eramons.github.io/techblog/post/raspi_radio/#8-passive-speakers" class="gblog-post__anchor gblog-post__anchor--right clip" aria-label="Anchor 8. Passive speakers" href="#8-passive-speakers"><svg class="icon link"><use xlink:href="#link"></use></svg></a></h3></div>
<p>And now? I needed some passive speakers to test if the little hifiberry amplifier was working.</p>
<p>I found some in my cellar - which belonged to an old home sound system - so I connected two of them to the miniamp using their cables, following the polarity I found in the miniamp documentation (references below). Black is minus and red is plus, as far as I know:</p>
<p><img src="/techblog/img/vintage_radio/connection.jpg" alt="Connection"></p>
<p>Surprisingly enough, it worked at the first try, the music was playing, much loudly as expected :D</p>
<p>I got two small passive speakers with an impedance of 4 Ohm and 3 watt of power. Then I connected them to the miniamp with thin copper wires, following the polarity I found in the miniamp documentation (references below) and taking into consideration that black is minus and red is plus.</p>
<p><img src="/techblog/img/vintage_radio/raspi_radio.jpg" alt="Raspi"></p>
<p>Surprisingly enough, it worked at the first try, the music was playing, much loudlier as expected :D</p>
<p>Now it&rsquo;s time to play a little around with the mpc client. First things first - adjust the volume before the neighbours come ringing at the door:</p>
<pre tabindex="0"><code>mpc volume 20
</code></pre><p>Then try to stop and play:</p>
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