The open-source balance board

This project is still under development.

Status update 2022-08-19 : This project has been delayed even more due to some technical/design/practical challenges that were discovered during the prototyping stage. It has become clear that the prototype is not suited for use by the general public yet. At this moment it is uncertain when it will be fully ready for demonstration purposes at club meetings.

What is it?

The word "Statera" is Latin for balance and the number "64" refers to the Commodore 64. So you may draw the conclusion that this project is for retro computing purposes and stop reading. But, that's not the whole story behind the Statera-64. Because this device is based around a 32U4 microcontroller that has native USB capabilities it means that it can also be connected to your PC or anything else that has a USB port. So this opens up a whole new world of controlling existing games and programs or new programs that are specifically written for use with this board. Now this device can detect how it is connected, if it is connected to an old computer it will go into retro mode and if it detects a USB connection, it will act like a USB HID device, like a mouse or game controller.

How it all started:

Some time before this project started, I discovered in my local thrift store, three Wii-balance-boards. One board isn't special, but three of them instantly triggered the tinkerer inside me. The boards were cheap, clean and appeared to be functional as I could spot no damage. What I didn't realize, was that not everybody will be in such a fortunate position of getting these balance board cheap. And prices might rise in the future...
Initially I wanted to use the ESP32 to make Bluetooth connection with the boards. I thought it to be a (relatively) easy way to interface a Wii balance board with a C64. But, the Bluetooth concept turned out to be way more complicated then I imagined. But not only that, with my intention of being able to connect 4 devices to a single C64, I realized that a wireless sollution, might not always be a reliable sollution. And that there was a great chance it would fail during crowded retro computer club meetings. Also the power consumption of multiple ESP32 might be too much for the C64 standard power supply. And finally, the need for batteries in the balance boards (knowing that batteries have a tendency of being empty at the most critical and unexpected moments), made me realize that this project could be made much easier if I was building it myself, from scratch. After all... a board with 4 loadcells and a micrcontroller... how hard could that be? So, I abandoned the idea of using a Wii balance board(s) completely.
The idea behind this project is make a fully open-source balance board, from easily available (new) parts. And to make it as much as possible compatible with existing games for the Commodore 64 computer. Now not every game will benefit from a balance board input device, but it certainly could enrich the gaming experience. Hopefully for some games it could really enhance the game experience and improve its play-ability. But most of all... this project should focus around fun.
After ordering (and waiting for) the parts, I took a breadboard, wrote some code, connected some loadcells and discovered that it was indeed not that difficult to achieve. So it was time to make a PCB, to keep everything nice and tidy. Below an image of my first experiments:

Regarding the Statera-64 retro computing:
There will be various operating modes: joystick, paddle and mouse (1351). If you operate it in paddle mode, you can connect up to four Statera-64 devices to a Commodore 64 computer, using two joystick ports and by daisy chaining two balance boards, just imagine the fun you'll have on parties. That is, if a game exists that allows this functionality to be used. I already know of a 4 player paddle pong game, don't know if it is as fun as it sounds.
This project is a combination between the joy board of the 80's and the Wii balance board of the past decade. Meaning that the Statera-64 is a very sophisticated and sensitive measuring device that is also able to generate the signals of a joystick, a paddle or even a 1351 mouse, allowing it to act as a controller. Meaning that it can interface directly to your retro computer like the Commodore VIC-20, C64, C16/+4, C128. But technically speaking, it can connect to any other computer with an Atari compatible joystick connector (although the timing for the paddle signals might need to be adjusted for that specific system). This balance board does not have any switches, so it doesn't make any noise when you use it.
Below a sneak preview image of the Statera-64 balance board prototype.

Regarding the Statera-64 and modern computing:
I'm concentrating on the retro computing part first, but I'm sure that it's possible to make this device act like an ordinary mouse or perhaps even game controller. But the mouse functionality would make it possible to control your PC with your feet. Don't know if that's fun or practical.