In this book, learn how the Arduino can be used as a hardware MIDI controller for Juce audio synthesis plugins through a series of practical projects, including a MIDI drum controller and an Arduino MIDI controlled pattern sequencer plugin. The book provides all the theoretical knowledge needed to design, build and test simple audio control systems, with C++ programming being introduced in a practical context for Arduino control. This learning in C++ leads into audio plugin development using Juce, significantly extending the level of programming knowledge involved. In so doing, readers will learn how control circuits work and how to build them, alongside developing practical software audio plugins that will allow them to progress their learning beyond the scope of this book. This book begins by introducing basic electronic circuit theory and microcontroller programming through a series of practical projects that summarise the material covered in each chapter. Starting with electrical fundamentals and systems concepts, the book provides an introduction to C++ programming to build Arduino based control systems for MIDI output. The second half of the book uses the Juce framework for audio plugin development to teach the fundamentals of software synthesis. Basic audio plugins are used to introduce concepts like FM and wavetable synthesis, ADSR waveshaping and audio effects. These synthesis techniques are then extended to include data driven synthesis methods like sequencing and pattern recall, leading to the project of an Arduino MIDI controlled pattern sequencer plugin. Learn with Arduino and Juce is an accessible beginners guide for students in audio electronics, audio dsp software processing, computer science, HCI, acoustics, music technology, aspiring professionals and hobbyists interested in audio electronics, music technology and audio engineering.