Application code structure

AN4173

18/22

Doc ID 023727 Rev 3

Figure 9.

Reconstructed signal at 10 Khz with sampling frequency 100Khz

The original input signal in green and the reconstructed signal in red can be considered

equal with the same frequency and amplitude.

This implies that if theoretically it’s possible to acquire input sinusoidal signal with a

frequency up to 500KHz using a maximum sampling rate of 1MHz (1µs) , in order to

reconstruct the original signal, only two samples per period will not provide the necessary

amount of information to obtain a perfect matching.

Using the ADC with DMA feature to avoid a big amount of CPU workload and a period

interrupt timer (PIT) to set a sampling rate, as suggested in this application note, it’s

possible to acquire sinusoidal signal with a good resolution of 5-10 samples for period only

considering that the minimum time needed for a conversion is around 5-10 µs, then signals

with a max frequency from 100KHz - 200 KHz.