from the when-geeks-get-bored dept.
The Floppotron has been upgraded to version 3.0. It's a very amusing project that has been going on for many years now.
The machine evolved into a relatively large system with multiple custom circuit boards and 3D-printed parts. While making the new Floppotron, one of the main priorities (if not the main) was finishing it in reasonable time. It's still a hobby project made after hours and not something commercial or mass produced, so you will find some nice solution as well as some janky, quick-and-dirty ones – and that's the beauty of hobby projects. Let's get a little more technical. To explain how the system works, I'll go through the overview first and then will get into details of each individual block. Here's a simplified schematic of the machine.
To make the old computer hardware play, we need a set of electronic controllers mentioned before but also a proper music (musical sequence) to play. A melody is encoded as a sequence of MIDI events, the same format as all digital synthesizers use. MIDI does not carry any actual audio data, but just short events, like pressing a piano key or twisting a control knob – you can think of it as a digital form of sheet music. Those events are send from the computer to the gateway using USB to MIDI adapter. The gateway is a custom nRF52 microcontroller based device which sits between the PC with MIDI adapter and the network of „instrument" controllers. It receives MIDI data and converts that data to RS-485-based internal protocol which can encapsulate MIDI and some extra stuff. The gateway, protocol and reasoning is described in further section. Those messages are picked by controllers which will turn the digital information into a sound by driving the electric motors or moving the hard disk heads. The controller consists of a common MCU board with Nordic nRF52832 chip and a driver boards specific to the „instrument", like floppy drive string, flatbed scanner or a hard drive. If you're wandering why there is a Bluetooth-enabled chip – I'll explain it too, but let's talk about how the sound is created first. [...]
We know that most people have seen the earlier versions but wait until you see version 3 - including smoke effects! But my personal favourite remains Bohemian Rhapsody - oh those dial tones!