2 replies to this topic

[Verdris]

I've gotten a rudimentary version of my frequency sweep program working, I just have a question about the language. Specifically, why do I need to specify a duty cycle each time I change the frequency? Here's the code that works:

        public static void Main()        {            PWM FreqOut = new PWM(PWMChannels.PWM_PIN_D10, 1000, .5, false);            int[] Frequencies = new int[10] { 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000 };            while (true)            {                for (int i = 0; i < 10; i++)                {                    FreqOut.Stop();                    FreqOut.Frequency = Frequencies[i];                    FreqOut.DutyCycle = 0.5;                    FreqOut.Start();                    Debug.Print(Frequencies[i].ToString());                    Thread.Sleep(4000);                }            }        }

 

But if I comment out line 25, then it gives me a flat signal until the frequency switches to 1000Hz, then pumps out the square wave as expected.

[Strut]

I've been  studying PWM in the new 4.2.2  firmware and this peaked my curiosity. Sorry in advance for asking questions instead of answering them

 

 

I see your using the Microsoft.Hardware.PWM namespace. Its interesting that the Secretlabs wrapper only exposed dutycycle. 1MHz is the current default PWM clock, I wonder if fractions are software enabled?

 

Will a start/stop work as expected if you don't change the freq?

[Chris Walker]

Hi Verdris, Internally, the NETMF PWM class stores dutycycle as duration and frequency as period. The duration is a subset of the period. So when you change the period (or frequency), you'll probably need to also update the duration (or duty cycle). Chris