I'm aware there is currently a discussion regarding communication between the Raspberry Pi and an Arduino but it doesn't match what I'm after and I didn't want to derail the OPs discussion.
Essentially I am creating a small electronic badge using a Raspberry Pi 3 B+ with a Hyperpixel 4 Touchscreen. The raspberry pi runs an apache web server where I have my the framework for my badge.
From what I gather the GPIO pins are all in use so the only alternative I have is communication over serial via USB. What I'm hoping to achieve, at least initially, is for an arduino + microphone to listen to music and detect the beat. This beat will then be sent to the raspberry pi to control a "party" animation on one of the pages.
I've had limited success with a serial library for PHP but it's just impractical when the beat from the arduino can be dynamic. Are there any other alternatives I'm missing?
I was considering Involt with the ARM build but wanted to increase my pool of options before I explored it.
What I've also tried, and it will work, is to use a Pro Micro to emulate a keyboard and send a keypress which a script on the webpage interprets. This is my current method but leaves a lot to be desired as well.