This is an audio output demo using the Raspberry Pi Pico with an LM386 amplifier to produce sound using a 8Ω speaker.
This code is based on the PWM/DMA code described in this blog post by Greg Chadwick.
It uses 8-bit PWM samples at 22050 Hz with a mixer to play up to 4 sounds at the same time (this number can be changed easily in the source code).
A synth loop (by Stereo Surgeon) is played in loop, and pressing the button connected to the Pico's GP16 pin triggers a small drum sound (by EKVelika).
Here are the schematics for the sound amplifier and the Pico connections:
NOTE: the 75Ω resistor connected to the SOUND_PIN was originally
68Ω, and the 100nF capacitor at the output of the LM386 was originally
50nF. I made the changes because I didn't have the original values
available, but everything seems to work fine.
This code includes parts of Greg Chadwick's PWM audio code described in this blog post.
It also includes mono/22050 Hz conversions of the following sounds released under Creative Commons:
- "Analog vintage Loop" by EKVelika (CC BY 3.0 License) - https://freesound.org/people/EKVelika/sounds/251248/
- "Insomniac Snyth Loop.wav" by Stereo Surgeon (CC0 1.0 License) - https://freesound.org/people/Stereo%20Surgeon/sounds/261208/