This is an update of my original Raspberry Pi / Pimoroni Unicorn Hat Visual Bloom Filter project. Check out the original article on my website, and the more complete README for the original on GitHub.
This version uses the Pimoroni Unicorn Hat HD in place of the original Unicorn Hat from the previous project. The primary difference between the two is that the original Unicorn Hat has 64 individually programmable LEDs (a grid of 8 x 8), while the HD version has 256 (in a 16 x 16 grid arrangement). The HD version uses a different Python library than the regular Unicorn Hat but this has basically the same API. As both products are the same size, this means that the LEDs are smaller / more densely packed in the HD version.
Besides the obvious hardware change from the Unicorn Hat to the Unicorn Hat HD, I also swapped the Raspberry Pi model A from the previous project for a Raspberry Pi model 3B. The Unicorn Hat HD doesn't require this, I just wanted to keep the previous project intact and had a 3B kicking around unused.
The code for this project (see app.py) is very similar to that of the original project. The primary differences are as follows:
- Use of the
unicornhathd(documentation here) library rather than the originalunicornhatone. - As there are more LEDs, the bit array that forms the Bloom Filter is larger with the HD product (256 bits rather than 64). I decided to use 6 hash functions with the HD version rather than 3 from the original.
- I set the brightness setting to a different value for the HD product vs the original.
Other than that, the project's the same as the original so for more detail and a description of what a Bloom Filter is and how it works, check out the original project's article on my website. I will add a new article and video specifically covering this version of the project at some point in the future...