I'm trying to convert the project here to an Arduino Nano.
I scaled the waveforms from 12 bit to 8 bit values. I replaced the
analogWriteResolution calls with
pinMode(10, OUTPUT) and
pinMode(11, OUTPUT) and changed the two
analogWrite calls to write to pins 10 and 11. Otherwise the program is unchanged.
My thinking (and this is where my poor electronics skills come into play) is that I just need a simple low pass filter to convert the PWM into the appropriate waveform (which, at startup, ought to be a sine wave on both pins). According to the article, the frequency generator tops out at 170Hz. I figure the PWM signal is going to be significantly higher than that, so I use R=3.3K and C = .1uF for my RC filter which ought to give me a -3dB at about 480Hz, but what I'm seeing on my scope is a mess. Not a stable signal at all.
This is the waveform I'm seeing on my scope:
Can someone educate me?
Update: BTW, this is the initial waveform which ought to be a sine wave.