MSP430 audio prototype

Audio filter example

The signal from MSP430 PWM pin isn't quite ready to drive a speaker or amplifier. First, we can clean up the signal a bit by running it through a low pass filter. This clips the sharp edges off the PWM waveform to make it sound a bit more natural. It's proper form to block any DC voltage from the signal using an electrolytic capacitor (POL-C1). The capacitor allows only the AC waveform to pass out of the circuit.