Henrik Carlsson's Blog

All things me.

posted this article on and tagged it with ΠiFi Music Player

Soldering a bit to see if I can get the Pi to read the changes in the potentiometer and use it as a volume control.

posted this article on and tagged it with ΠiFi Music Player

I’ve started dabbling with amixer and alsamixer for the PiFi’s volume control. Seems fairly simple. Next, I need to make a physical volume control.

The πFi Music Player

posted this article on and tagged it with ΠiFi Music Player

Every project needs a name and I need to stop referring to the music player I’m building as "The Kid’s Music Player". So, the project name is from now on The πiFi Music Player or πFi for short.

The basic idea is to replicate the very kid friendly1 way of listening to music that a cassette player or CD player was back when I was a kid. Today we can all access pretty much every piece of music ever recorded but to do so you pretty much have to have a smart device of some kind and be able to read and write to find what you are looking for.2

To do this I’m building a device that scans pieces of cardboard with QR codes on them and then uses the information on the QR code to playback the correct track, album or artist from Spotify. (Local play might also be a feature.) The side of the "music card" that doesn’t have a QR code will have album art or similar to make it easy to identify to both adults and kids.

I currently have a soon to be alpha in my hands (or on my bookshelf). I’m using a Raspberry Pi with Mopidy for the playback, a Raspberry Pi Camera module and zbarcam to scan the QR codes, a Python script to actually do something with the information in the QR and then a HiFiBerry Amp2 to DA convert and amplify the audio for a pair of passive speakers.

As you can see in the video the physical/crafty side of the project has a lot of work that needs to be done. I’m currently using some LEGO to keep things in place, but I need a proper enclosure. I’m not 100% sure whether I’ll make something out of wood, metal or whether I’ll 3D print something unapologetically plastic. 3D printing seems like a good idea because it simplifies making more than one device, which I’m planning to do. However, I’m never 3D printed anything. Nor have I built a 3D model of anything, so I’ll have some homework.

Even more important before it can be considered even an alpha is a volume control. Right now, the only way to control the volume is to SSH into the Pi and use mpc volume XX where XX is the percentage of volume I want. Because the amplifier is 2x 30 Watts, it’s quite loud in a normal home setting. As I’m listening while typing now I have it set for 7% volume.

The WAF of SSHing into something to change it’s volume from ear-piercingly loud to tolerable is very low.3

I also think it need some kinds of physical controls, at least for play/pause, stop and next track. Right now those functions are also accessed via QR codes.

Before moving it into beta I also need to build speakers. I have borrowed the ones I’m using now from a friend. I might also build a proper power supply for it, instead of using the wall wart that I use now.

Many things are still uncertain and there are so much I need to learn how to do, but I am really happy to have started this project, and that I actually got back to it after having left it dormant for three mounts.

If you want to follow along everything will be published here on the blog. I’ll try to remember to tag all the posts with πiFi Music Player.


  1. Or "non techy person" friendly.  ↩

  2. Yes, I am aware of "smart speakers", ladies in cans and "AHOY TELEPHONE". Here’s some reasons why that’s not a solution here.  ↩

  3. Yes, "Wife Acceptance Factor" is probably a very problematic term these days. I think we should try to change it to "PAF – Partner(s) Acceptance Factor". The idea itself, that something that appeals to a nerdy person doesn’t necessarily appeal to the other person(s) living with the nerd, still has merits and is worth considering when building and/or purchasing something like this. Regardless of the gender and/or pronoun of the nerd and the other person(s) involved.  ↩

posted this article on and tagged it with The Kid's Music Player ΠiFi Music Player

It works!

posted this article on and tagged it with The Kid's Music Player ΠiFi Music Player

Time to test the HiFiBerry as well.

posted this article on and tagged it with Shopping Lists

So I guess I’d very much like any recommendations of easy to use shopping list apps where I can also share lists with Linn.

Replies and comments

posted this article on and tagged it with Stranger Things

We’re three episodes in on *Stranger Things* season three. So far the lows are lower than before because it gets sillier than usual but it’s also much more scary than previous seasons so I think I like it more than season two.

Replies and comments

posted this article on

”Vård ska man få efter behov, inte efter sjukvårdspersonalens önskemål”, säger Lina Nordquist, sjukvårdspolitisk talesperson för Liberalerna.

Svårare än så är det inte.
Rätten till vård går före

posted this article on and tagged it with iOS 6

I just setup an old iPod Touch for Iris to have as her first MP3 player and I gotta say that iOS 6 feels like an old friend.

Zodiac

posted this article on and tagged it with David Fincher Movie reviews Movies

Yesterday when Iris was asleep in her bed, Linn and I sat down on the couch to watch some TV. We’ve just finished the latest season on Modern Family that’s available on Netflix in Sweden1, so we needed to find something new. While browsing for a while, not managing to agree on something, Linns sleepiness got the best of her and she decided to fall asleep on the couch instead.

Even though I was really tired I decided to watch something. Initially I was going to start watching Luke Cage but while browsing a list Zodiac by David Fincher showed up. I tend to really like Fincher’s movies and since I hadn’t watched this one, and since it was still reasonably early in the evening, I went with it. At first I thought I might watch half of it or something and then continue another day but the movie drew me in.

It’s a mystery-thriller based on the actual case of a serial killer who called himself ”The Zodiac”. It features a great cast, including Jake Gyllenhaal, Mark Ruffalo, Robert Downey Jr. and Chloë Sevigny, and I loved it.

I knew very little about it when going into it. I wasn’t even sure if the text at the beginning that proclaimed it to be based on actual events were true or not2 but it totally got me hooked in just a few minutes.

The thing that I really like about David Fincher’s movies is that he thinks, or at least the movies gives the impression that he thinks, that I the viewer is an intelligent and observant person. He loves exposition but not in a bad way.

Also this movie, unlike Fight Club and Gone Girl – which are the two most Fincher movies that I saw most recently3 – is free of irony. It’s an honest thriller that has me invested in solving the crime and that, in a few instances, makes me genuinely scared.

Oh, and in case you don’t obsessive click all the links that I put in this post, you should absolutely check out this one, David Fincher – And the Other Way is Wrong, from Every Frame a Painting. It’s a great analysis of Fincher’s style and as far as I can tell it doesn’t really spoil any of his movies, so you can watch it even if you haven’t watched all his films yet.


  1. I think it’s season 7. 
  2. It is. 
  3. I saw Gone Girl for the first time, Fight Club was a rewatching.