La boîte à musique

I found some time to add another sample of La boîte à musique output for the Hackaday Music contest.

Recording analog is now pretty complicated on modern computer since constructors does not provide line port anymore ... I reused my TI PCM2900 "breadboard" USB sound card, but breadboarding USB and audio is not really efficient : it took me some times to make it works correctly. I'm now willing to design a PCB with Kicad to have a line in/line out soundcard handy.

Anyway, there is a sample with the "Punk-Rock" profile :

https://soundcloud.com/julbouln/419624965a

After a small revision to the board, I finally ordered it on OSHPark. The revision includes a new stereo pot to control headphone and speaker output volume. I changed the micro USB SMD connector with a through hole mini USD because I had to resolder the SMD part multiple times. Finally I added the possibility to have a functionnal board without optional speaker/amp and battery parts.

Once populated and soldered I discovered that I can't get the initial firmware to work... I originally used mbed but after trying for some hours I couldn't get it working. I imagine that I changed something in mbed directly but impossible to find it out. So I decided to change platform from mbed to libopencm3 plus atomthreads and make a new firmware (almost) from scratch. It was actually a great experience which take only a few hours and new firmware is better than the original one.

I discovered that my laptop doesn't have any line in to record some music from la boîte à musique. I decided to create a small usb card to do that using PCM2900. I just soldered the chip on a tsop to dip breakout and put it on a breadboard with needed passives.

More to come !