Blinkekatze

What is it?

Blinkekatzen are a replacement PCB for commercially available silicone LED lights.
The lights usually contain a battery, some RGB LEDs and an optical diffuser in a soft cat shaped translucent silicone housing. The light emitted by the LEDs hits the diffuser and lights up the outer cat shaped silicone shell.

Blinkekatzen expand on this concept by adding processing, sensing and wireless communication capabilities through an ESP32-C3 microcontroller and various sensors to react to interactions such as squeezing or booping the individual cats.
When multiple Blinkekatzen are deployed together within wireless range, they automatically form a network in which interaction with one cat also affects other cats close by.

How does it work?

By default Blinkekatzen are slowly shifting the hue of their color. They also constantly measure internal air pressure and acceleration to detect interaction with them. When squeezed the internal air pressure rises and when bonked a sharp spike in acceleration occurs. Both those interactions directly affect the current color of the cat.
Squeezing desaturates the color, turning the cat more white. When squeezed more heavily, the hue is also shifted toward red and more saturation is applied again to show that the maximum level of squish has been reached.
Bonking of a cat briefly increases the brightness of the color shown, resulting in a short flash of light for every bonk.

In addition to changes in local color of the cat, each of the interactions above is also broadcast wirelessly to all other Blinkekatzen in range, causing them to also react with a change to their color.

Other than for squeezing and bonking, Blinkekatzen also periodically exchange data to stay synchronized with one another. This is required to ensure that the hue of a group of Blinkekatzen stays synchronized over time. It is also possible to override the color shown by a Blinkekatze remotely, enabling direct control for scenarios where centralized control is required.

Color accuracy

To ensure the colors displayed by Blinkekatzen look true to the eye, the Blinkekatze firmware supports color calibration, ensuring perfect color accuracy and gamma correction. This is particularly important when using Blinkekatzen from different production runs together, as the color profile of the LEDs used in the Blinkekatzen can vary significantly between them.

Links

• Hardware: KiCAD design files
• Firmware: ESP-IDF source code

Blinkekatzen in the wild

Over the past months Blinkekatzen have been at a number of hacker events.

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