[sdiy] newbie question Can a simple PIC16F628A be used as an audio filter trigger like a light organ

[rsdio at audiobanshee.com]

You might need two digital pins to drive the Reset and Strobe signals, then a third pin for the ADC. The PIC16F628A doesn't have an ADC, though, so another MCU choice is needed.

You also need to make sure that the ADC is not delta-sigma (like most audio ADC chips), because the output of this 8-pin chip multiplexes the 7 bands on the same pin. Delta-sigma wouldn't work because it assumes every sample is related to the previous one and that discontinuities are smoothed by filtering. Fortunately, most on-board ADC modules in 8-bit or other embedded processors are not delta-sigma, and so they can handle multiplexed analog signals without a problem. In fact, many MCU chips have a built-in analog mux ahead of the ADC, and so they already have incentive to choose an ADC design that is compatible with analog multiplexing.

Brian


On Feb 24, 2016, at 8:42 AM, Jay Schwichtenberg <jays at aracnet.com> wrote:
> This chip might be useful for this type of application depending on the
> frequency bands you want. It basically samples the frequency bands and you
> clock out voltages for each bands amplitude measuring the voltage with a
> ADC. So the mcu needs at least one digital pin and a ADC.
> 
> https://www.sparkfun.com/products/10468
> 
> Jay S.
>