AVR-Chat

> ... I'm a beginner at all of this.

One would never know; you have a good grasp.

PWM DACs are based on averaging pulses to a corresponding equivilent 
voltage or current.  The average is usually generated by using an RC, a 
simple filter that reduces high-frequency components, and it's values 
depend on your need.

If you are generating a stable DC offset voltage, for example, you need 
a long time constant - perhaps limited by the load resistance.  If 
you're generating an AC signal, the filter needs to be faster - perhaps 
limited by the source impedance.  In both cases the instantaneous error 
is caused by the filter characteristics and, in both cases, an opamp can 
help.


Tom