==== PWM ====
Using a simple [[PWM]], data is entered at a certain speed, the [[PWM ]] clock speed.
If you simulate a constant [[PWM ]] output signal at middle range of voltage (state just between 0V and 5V : 2.5V), it results an alternance of 0V and 5V, that result in a noise sound. In Arkanoid, this defect make some continues sounds instead of silents...
My idea is generating a sound having a frequency upper than dog ultra sound, while I want to simulate a constant 2.5V.
For this I do use two clocks entries in my [[PWM ]] : one about data entry, and another about algorithm execution.
This result a high quality sound output (in addition to this nice [http://www.fpgaarcade.com/library.htm Yamaha sound chip from fpgaarcade])