For DIY, how to program Arduino Mini Pro to act as an Audio Frequency White Noise generator?
a) using one Digital Output pin
b) feed to a simple passive RC low pass filter to reduce out of band signal
c) feed to a simple class-D IC chip audio amplifier and speaker
d) since it is DIY and noise, lo-fi (not hi-fi) is good enough.
a) How to program?
b) Wonder if it is better to use to chip act a Pulse Width Modulated 'digital to analogue converter'?
c) How to calculate value for RC filter (assume amplifier has high input impedance)?
Many years ago, I have programmed a hardware sound generator chip as part of a game machine. It has two registers for amplitude and 'frequency' control (band of 'white' noise). It worked very well. I once looked at the output using oscilloscope and it was square wave. I believe that it works, basically, using the above principles. Since I do not have the chip now, I cannot verify it. Now, I would like to duplicate its function using Arduino in software.