Build Instructions

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• 1

  Concept

  Key component: Rpi Pico.
  

  A lot of USB programmable pedals on the market need to install an application for configuration. Usually this app is only for Windows and came poorly translated (if translated at all). This is a pitfall for Linux or Mac users, who have only two options: To install a Windows virtual machine or ask a favor to a Windows user for pedal setup.

  Here come to the rescue Raspberry Pi Pico, for two big reasons: USB native interface, so no programmer or additional hardware needed for firmware download and the most important: CircuitPython support. Programming could be “on the fly” without compiling-and-download during the debug phase. So Rpi Pico is the best candidate for a DIY pedal.

  Another additional advantage over commercial USB pedals, the pedal itself can be replaced for a more robust one, without touching the circuit. Another kind of switches could be used, so operation with different parts of the body is possible. The amount of switches to be installed is only limited by Rpi Pico GPIO pins and the space available on the enclosure.

  The circuit is built using TUSISTEMITA hardware prototyping system, which provides different kinds of prebuilt modules which allows to build an electronic project without soldering, but making it very robust and expandable. All the parts are enclosed in a dustproof and waterproof IP65 box. This enclosure gives an “industrial look” to the project and also adds mechanical strength to withstand abuses. The external electrical connections (pedals, and USB) were fitted with IP accessories to provide a good seal.

• 2

  Key features

  • Developed using CircuitPython, friendly and easy to learn
  • Compatible with the most common operating systems
  • No need to install apps for initial firmware download
  • Key configuration done in a text file
  • Splash resistant and shockproof
  • Detachable and replaceable pedals
  • Built using hardware prototyping system
  • Powered by USB, no additional power source needed

  The hardware is pretty simple, only requires a Rpi Pico and switches connected between GPIO and ground. Internal pull-up resistors used. Power and data via USB cable

• 3

  What is CircuitPython?

  In Adafruit Industres words, makers of CircuitPython:

  CircuitPython is a programming language designed to simplify experimenting and learning to program on low-cost microcontroller boards. It makes getting started easier than ever with no upfront desktop downloads needed. Once you get your board set up, open any text editor, and get started editing code. It’s that simple.

  Other reasons to use CircuitPython include:

  • You want to get up and running quickly. Create a file, edit your code, save the file, and it runs immediately. There is no compiling, no downloading and no uploading needed.
  • You’re new to programming. CircuitPython is designed with education in mind. It’s easy to start learning how to program and you get immediate feedback from the board.
  • Easily update your code. Since your code lives on the disk drive, you can edit it whenever you like, you can also keep multiple files around for easy experimentation.
  • The serial console and REPL. These allow for live feedback from your code and interactive programming.
  • File storage. The internal storage for CircuitPython makes it great for data-logging, playing audio clips, and otherwise interacting with files.
  • Strong hardware support. There are many libraries and drivers for sensors, breakout boards and other external components.
  • It’s Python! Python is the fastest-growing programming language. It’s taught in schools and universities. CircuitPython is almost-completely compatible with Python. It simply adds hardware support.

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