PWM waveform

Hi,

I want to see the PWM waveform with an oscilloscope. I am waiting for a pretty square waveform, but I get dirty signals (50% and ~90%)

How to explain that?

Thanks

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Looks like your oscilloscope is set to AC and not DC. That puts a DC-blocking capacitor in the line to remove DC offsets from your AC signal. If you want to see absolute voltages, use the DC setting.

Hi, looks like you haven't got the gnd lead of the cro probe connected to the arduino gnd, but johnwasser is probably right.

Tom.... :)

Looks like a problem with your ground lead.

TomGeorge:
Hi, looks like you haven’t got the gnd lead of the cro probe connected to the arduino gnd, but johnwasser is probably right.

Tom… :slight_smile:

TomGeorge, charliesixpack, it was actually that !

Thanks!

127.bmp (276 KB)