Graphing PWM and Duty Cycle

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Re: Graphing PWM and Duty Cycle

Postby Martyn » Mon Nov 11, 2013 10:29 am

You can use a maths channel to display a representation of the duty cycle.

If you use integral(A) you will have a graph that will rise as duty cycle increases and fall as duty cycle decreases, this works because the integral gives you the area under the curve.
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Re: Graphing PWM and Duty Cycle

Postby Robski » Mon Nov 11, 2013 2:15 pm

Martyn,

Which 'time' will this respond to, high or low ?
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Re: Graphing PWM and Duty Cycle

Postby Martyn » Mon Nov 11, 2013 3:49 pm

If you have a square wave with 50% duty cycle, centred about the 0V, you will get a triangle upwards when you have a positive pulse and a triangle down when you have a negative pulse. Repeat multiple cycles across the screen and you will see a sawtooth wave, the more cycles on the screen then the more sawtooths. It is not related to the time as it is just looking at the screen trace. Now if you change the duty cycle the saw tooth will move up or down, the greater the change, the greater the movement.

Please note that with streaming trace this will only appear once the screen is complete, the maths channels currently require a screen of data before they can be drawn (watch this space for a future update on this :wink:)
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Re: Graphing PWM and Duty Cycle

Postby Robski » Mon Nov 11, 2013 7:15 pm

ahh thanks for that, i was under the impression it was a flat line so to speak & not saw tooth.
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