The description about the "linear frequency change" in lab 4 isn't correct

[chenyikuan110]

I assume the STEP parameter used in the "sq_wave_gen" module is a constant parameter that determines how much the period of the sound should change upon pressing button 0 or 1, in which case the thing that gets linearly adjusted is the PERIOD rather than FREQUENCY of the sound (because linear change in frequency results in non-linear change in frequency). If this is the correct interpretation, then the description of this part of the lab should be modified.