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Topic: Timer generated square wave output unclean (Read 140 times) previous topic - next topic

psteen

Hello Folks!

I use Arduino uno v3 to generated square wave output for a small frequency generator in the range 500kHz to 2MHz. That works, but the output is unclean, it is square wave, but not clean, it contains of periodic overshoots and rising/falling edges are more like slopes in the 1MHz to 2MHz.

I tried to mitigate it by putting a resistor of 10K to ground from the output, it did not help so I tried to use also 1K, that did not help either.

The uno is supplied by the USB cable from the PC. I did not test yet using batteries to supply it with power.

I know I can connect an external logical gate (using some ic from HCT family) to clean it, or use a bandpass filter. But that adds extra components, I don't want.

Anyone who have faced this issues ?
Systems engineer.

Grumpy_Mike

Quote
but not clean, it contains of periodic overshoots and rising/falling edges are more like slopes in the 1MHz to 2MHz.
That is an artifact of your measurement system. You need a proper probe and a high bandwidth scope to see a sharp rise on a 1MHz signal.

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