I’ve had success by ripping the ‘speaker’ out of a pair of old headphones, connecting it to C and Ground, and running the attached code to generate tones. I haven’t managed to get it to run any faster, so this is the smallest step-between-tones I can achieve.
Note that if you run it disconnected, powered by battery, the tones get higher and smoother. I think because the crumble is not polling the computer while it runs?
Also see attached a ‘squeak’ sound! 🙂