The developer and mastermind behind the Needle Nose Pliers blog is using a Raspberry Pi Pico to drive a custom audio spectrum analyzer. This project uses the Pico to process audio input and output; a visualization of the sound it detects to a small OLED screen in real-time. This project is essentially the same sort of visual generator you’ll find in many media players; that show a sound wave that wiggles and moves based on whatever audio you’re playing. A full breakdown of the project including a demo is available on the Needle Nose Pliers blog.
According to the blog post; the original plan was to develop the audio spectrum analyzer using an Arduino Uno; which has 32 KB of flash memory. However, this plan was ultimately abandoned; because of its memory restrictions; and the Pico was selected as a stand-in thanks to its greater 2 MB flash memory capacity.
Thankfully, this project design—like most of his other work—is shared as an open-source project; with plenty of details available for anyone who wants to recreate it or develop something similar. As we mentioned above, everything is driven by a Raspberry Pi Pico. It outputs to a .96-inch OLED with an SSD1306 interface. Audio samples are input to the Pico through AC coupling and biased with a resistor to be read as ADC input.