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The Color of Music 音乐之色 | Cypress Semiconductor

The Color of Music 音乐之色

"It occurred to me by intuition, and music was the driving force behind that intuition. My discovery was the rest of musical perception." - Albert Einstein on his Theory of Relativity.

Music is one of the most magical creations, even to Einstein. Both math and music deal with vibration and harmonics. The tone of music is decided by frequency, and the sound of music is based upon the richness of the harmonic contents. What about the color?

I can be persistently annoying when there is a goal in my mind, and this behavior showed itself well when I went after Dennis Seguine, one of the most respected engineers at Cypress, for a cool demo for our new PSoC 1 CY8C28xxx device. Actually, I bribed him with 20 CY8C28xxx samples :-) Engineers cannot turn down offers of cool gadgets.

Two weeks later, Dennis successfully combined his passion for music, banjo and PSoC into his invention “The Amazing Banjomatic”. It is a board equipped with 272 LEDs in four colors, and can be installed behind the drum head. The colors of the LEDs respond to the frequency of the tone, while the expansion of the LEDs reflects the volumes.

This design utilized the simultaneous 4 Delta Sigma ADCs with dedicated decimators in CY8C28xxx, which is also Dave’s favorite PSoC 1. This display for each section is a stacked row of LEDs, 4 columns, 10 rows one each side for a grand total of 272 LEDs. The linear output of each channel is converted to a logarithmic (3 dB per step) display with a look up table. The colors are scanned sequentially, evaluating the level in each channel. The row and column selections for each color are made by turning on port 1 and 2 outputs according to another table. Each channel is updated at a 50 Hz rate. Each LED is driven at the same peak current. Some LED colors are more efficient than others, so the duty cycle is varied by color to maintain constant "apparent" brightness. The physical nature of a vibrating string is to maintain resonance longer for lower notes. Thus the high frequency channel has an increased duty cycle to balance brightness and compensate for the relative inefficiency of green LEDs. The LEDs are driven by P-channel FETs for each column (or color) and N-channel FETs for each row.

Einstein got his share of attention as scientist, engineer, and musician, and I am sure Dennis has been getting his share too :-)

 

 

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