“A tiny violin for playing tiny tunes
Designing and building this tiny violin was a fun way to experiment with building my own microcontroller development board from scratch, as I’ve been meaning to do for a while. So I’ll be documenting the whole process here, from PCB design to programming the microcontroller.
1. Circuit Schematic and PCB Design
The first step was choosing the microcontroller I was going to use, based on the functionalities I wanted my violin to have. I needed at least one PWM pin for the piezoelectric buzzer and another two digital pins for the LEDs and for the push-button, so the ATtiny85 turned out to be the perfect fit.
The circuit schematic is fairly simple. The ATtiny85 controls two LEDs and a piezoelectric buzzer, and I also added a push-button for switching between songs. The whole circuit is powered by a 3.7V LiPo battery.
I wanted to make the PCB as small as possible, in order to be able to use it as a badge, so I found the tiniest microcontroller package (MLF-20).
As an extra feature, I also connected the strings of the violin to an analog input of the microcontroller, in order to actually be able to play the violin by touching the strings with a conductive material.”