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Former Member

a sine wave is applied at a0 using a diode,so that it geets rectified and then after pwm the square obatIned is only with wrt positive cycle ,i need to generate pwm  even during negative cycle and one way is to do it by full bridge rectifier .so is there any way by arduino coding i could get it

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  • 0 in reply to Former Member

    You are outputing a PWM signal based on the incoming sine wave. Get rid of the rectifier and sample the sine wave directly - you'll get values from 0 - 1023 from the ADC. Take the mean of every incoming value like this:

     

    mean = mean + (new value - mean)/k

    where k is chosen to set the time constant of the rolling averaging (big k means many sample are averaged together)  if you you use integer arithmetic then take care with overflows and rounding.

     

    Then for each sample do:

     

    pwm = abs(new value - mean) * k2

     

    where k2 is a number you choose to set the gain from input analogue to pwm out.

     

    I don't play with Arduinos so you'll need to write the actual code yourself - if you mean to do much of this kind of work then you should learn to code in C and you will learn far more if you don't use the Arduino libraries (but everything will take longer to code).

     

    MK

  • 0 in reply to Former Member

    We need to send same values of PWM to negative cycle. If we measure negative supply, output will be zero as diode blocks negative supply. We need to send psuedo values to negative cycle.

     

    ...you should save the ADC values during the +ve cycle and access them during the -ve cycle and load them to pwm. Use an array to save the values and step through it with a counter first to save then to access.

     

    https://www.arduino.cc/en/Reference/Array