Audio spectrum LED display based on MSGEQ7 and ATmega328
A simple seven-band audio spectrum display based on the MSGEQ7 chip. An op amp upstream of the MSGEQ7 allows some adjustment of level through an audio pot that regulates negative feedback. The MSGEQ7 chip is set up per the example in the datasheet, so frequency ranges should be same as the datasheet. The MSGEQ7 outputs voltages proportional to sound in each band, multiplexing them on a single output. The ATmega328 takes care of timing signals that manage the MSGEQ7. The microprocessor also directly drives an eight (amplitude) by seven (band) LED display, illuminating one LED at a time, but quickly cycling through them using persistance of vision to create a flicker-free display.
The project is described in detail on my blog: