Re: Generating sound at microcontroller pin using pwm

On May 15, 12:20 am, Rohit <papakap...@xxxxxxxxx> wrote:

I do not understand this. could you please explain the process to do
this. I do not want to use a DAC.
Can i implement what you are suggesting with just pwm? Currently I am
generating square waves of 50% duty cycle
with different frequencies to produce different notes of keyboard.Do
you mean i must also vary duty cycle of the pulses.

You seem confused on what PWM is - you claimed to be using it, then
state here that you always use 50% ?.

If you want to vary the amplitude, you need other than 50% - Varying
the duty cycle is a cheap way to vary the energy, but it does also
affect the spectrum - if you want to preserve harmonic shape, then you
need an external means of Amplitude control.
In a simple uC, you could use one PWM as a slower DAC for envelope
shape, and a 2nd PWM driving an external SPCO Analog switch, to give
frequency control.

Or, you can just move up in frequency, and use single PWM as a faster
DAC, and use the uC to 'play back'
a recorded waveshape. That will give the best sound-effect quality by
far, and large flash memory really is cheap.

-jg
.

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