Hardware and software for making LED strips glow in interesting ways while music is playing.

Mainly created by Matt Peddie and Henry Hallam; inspired by the world-famous tEp leit show.

Hardware:

• STM32F4 microcontroller (168 MHz 32-bit ARM Cortex-M4)
• N output channels (4 in prototype), each provides PWMed 12 volts at up to several amps, using low-cost MOSFETs
• Stereo jack audio input at line level with pass-through for connection to speakers. AC-coupled to microcontroller ADC pins, resistor-biased at half of the 3V microcontroller supply.
• USB I/O to PC for firmware updates, tuning, and advanced shit.

Software:

• ADC is sampled at 11 kHz, feeding a bank of IIR filters from which several bandpass bins are constructed across a range of audio frequencies.
• Bins are low-pass-filtered, and a set of gains and cutoff thresholds are applied to form the LED PWM duty cycles.
• The gains and thresholds are adaptively adjusted to maintain a certain goal activity level and mean brightness.