Light up an LED with your Raspberry Pi's audio output! We (Tyler Trinh + Matt Wiens) used a Raspberry Pi (RPi) 3 model B, with Ubuntu MATE running as the OS. Likely this will work on older (and newer, once they're out) RPis, too.
Audio is captured from your computer with PyAudio, which on Ubuntu you can install with
sudo apt install python3-pyaudio
Make sure your firmware is up to date as well. If it isn't, you might run into audio issues (like we did). To upgrade to the latest firmware run
sudo rpi-update
If you want to test whether the audio processing works, run
./rpi_volume_led.py --test-pyaudio
and if it works you should see the RMS of your audio output being printed to the terminal. Note that this test runs independent of the Raspberry Pi, so it will run on any machine.
Wire up a breadboard as shown below, making sure that the longer end of the LED is in the same row as the resistor (which should be around 270 ohms). In the left column of the RPi pins, starting from the bottom, the third pin is ground and the sixth pin powers the LED, and is identified as pin 12 from within the program.
To test that the LED is properly connected, run
sudo ./rpi_volume_led.py --test-led
and the LED should start pulsing a few times. (Note that we need to run the
program as root now that we've started using the RPis GPIO pins.) If you
used a different pin from pin 12, say, pin 18, you can specify the number using
the -p option:
sudo ./rpi_volume_led --test-led -p 18
You can also specify multiple pins using the -p option.
To run the program normally run
sudo ./rpi_volume_led
and hit enter whenever you're done to tell the program to clean up and exit.
rpi-led-lightshow, which is an expanded version of this project.