The original design of the audio echo example runs with 8 kHz
sampling frequency for longer echo time. I changed this to 48 kHz
sampling frequency. Changed the system clock from 24 MHz to 50 MHz
to have default timing constraints.

Based on the echo example I build an audio interface which provides
the audio interface with parallel data.

in all design projects of lab #3

hence, adding add1(truthtable) to the makefile.sources