square waves (or pulse waves) 8 Hz duty cycle?

[Rudy M]

Hello everyone,
I'm still busy testing QB64PE. 
For a later experiment, I want to use the PC as a square wave generator (or pulse generator). 
One of the low frequencies I need is 8 Hz. 
This isn't possible using the Sound statement (cfr frequency lower then 30Hz...)

But via F1 help on the _SNDRAW item, I discovered the QB64PE example for sine and square waves. 
To my great surprise, this works on my old Lenovo ThinkCentre PC from 1 Hz! 

Okay, I'm very happy with that. 

But.... Does anyone know if it is possible to regulate the duty cycle with this _SNDRAW statement?

Code: (Select All)

'Source: QB64PE (_SNDRAW + F1)



'Sound using a sine wave with _SNDRAW Amplitude * SIN(8 * ATN(1) * Duration * (Frequency / _SNDRATE))

'Explanation: The loop Duration is determined

' by the number of seconds times the _SNDRATE number of samples per second.

'Square waves can use the same formula with:

' Amplitude * SGN(SIN(8 * ATN(1) * Duration * (Frequency/_SNDRATE))).

'any frequency desired from 36 to 10,000



'FREQ = 1 'Test Rudy (works on my PC)

FREQ = 8 'Test Rudy (works on my PC)

'FREQ = 10000

Pi2 = 8 * ATN(1) '2 * pi

Amplitude = .3 'amplitude of the signal from -1.0 to 1.0

SampleRate = _SNDRATE 'sets the sample rate

FRate = FREQ / SampleRate '

FOR Duration = 0 TO 5 * SampleRate 'play 5 seconds

  '_SNDRAW Amplitude * SIN(Pi2 * Duration * FRate) 'sine wave

  _SNDRAW Amplitude * SGN(SIN(Pi2 * Duration * FRate)) 'square wave

  ' Works for a frequences starting from 1 Hertz (old Lenovo ThinkCentre, Linux Mint 22)

NEXT

DO: LOOP WHILE _SNDRAWLEN

END