This is a pure sine wave, captured by the ADC + DMA code, as described previously:
The plot above consists of 800 samples, sampled 40 µs apart, i.e. at 25 kHz - for a total of 32 ms. A quick calculation would seem to indicate that we’re seeing 1.6 cycles of a 50 Hz sine wave.
Except that it’s not… the incoming signal used here was a 24,950 Hz sine wave!
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