Have you ever dreamed of creating an instrument that combines art and technology? I recently set out to build a motion control project that plays music using stepper motors, and what started as a crazy idea turned into a fascinating journey. In a world where others had already explored this concept, I found myself without any guides or tutorials. But I'm a DIY enthusiast who loves challenges, so I decided to create my own version from scratch. The result is a system that can play music using midi commands sent through a USB serial interface, and it's all powered by an Arduino microcontroller. In this project, you'll learn how to bring your creative ideas to life with motion control, and how to create a fully functional music player using stepper motors. From the hardware plans to the software instructions, I'm sharing my entire process so you can replicate it and start creating your own unique soundscapes.

In this third installment of the mini series, we're diving into the nitty-gritty details of controlling multiple stepper motors with precise timing and frequency accuracy. The key to achieving this lies in understanding how to efficiently handle interrupts, utilize internal timers, and minimize clock cycles. The author breaks down the implementation into manageable chunks, starting with the initialization process, where they configure the output pins and set up the interrupt system. The use of a 48000 Hz timer call results in an extremely accurate representation of the desired frequency range, thanks to the internal pre-scaler. However, it's the main interrupt function that showcases the real complexity of this project. Here, we see how the author employs local copies of port pins to speed up operations and mitigate potential race conditions. They also utilize a clever trick to reduce instruction cycles by using a register instead of accessing RAM. The final piece of the puzzle is the `setChannel` function, which allows users to adjust the frequency and enable/disable specific channels. This function cleverly incorporates a formula that calculates the new counter value based on the desired frequency, ensuring smooth transitions between states. With this code, you'll be able to experiment with various configurations, including reducing maximum frequencies and expanding the system to accommodate more stepper motors. If you're interested in exploring further possibilities, feel free to reach out to the author for more information.

In my previous post, I showed you how to control a "Music" play using stepper motors with Arduino and MIDI protocol. This time, I'll be focusing on the software side of things, specifically the code that brings it all together. The midi2stepper.ino file is where the magic happens. It reads incoming MIDI messages from the serial port and decodes them into frequencies to be played by our stepper motors. The algorithm used is quite clever, as it assigns each note to a free stepper motor, rather than just playing one specific motor for all notes. One of the most interesting parts of this code is how it handles note-off events. Instead of simply turning off the volume, it finds an active channel with that frequency and turns it off. This allows for more precise control over which motors are being used. Of course, there's still more to explore in this software - particularly in the midi2stepper.cpp/.h files, where things get a bit hairy (as I like to call it). But for now, let's just say that we've covered the basics of how MIDI messages are interpreted and turned into stepper motor movements. Want to see more? Head on over to the next post in this series, where we'll dive deeper into the code and explore some of its intricacies.