The Pmod ADC, and an analog signal generator are required for this demonstration.

In this demonstration, an analog waveform is generated using the Digilent Analog Discovery 2, and the Waveforms software:

Digilent Analog Discovery 2

For the waveform to be displayed, we collect multiple points in each period. However, according to the Nyquist theorem, the sample rate only has to be $2\times$ the frequency of the signal.

The following block of code is just an example. For the Pmod ADC, the minimum delay between two samples is around $0.3\,$ms (corresponding to a sampling period of $3\,$kHz). So the maximum frequency of the input signal can be $1.5\,$kHz.

For the interface ID used in the following example, if the Pmod ADC is connected to interface PMODA, type in PMODA; if the Pmod ADC is connected to interface PMODB, type in PMODB.

For the WaveForms configuration, this example uses the following parameters:

Wavegen Parameters Configuration
Type Sine
Amplitude 1V
Offset 1V
Symmetry 50%
Phase 0

Channel 0 (V1) on Pmod ADC is connected to port W1 on Digilent Analog Discovery 2.



In [1]:

from time import sleep
from pynq.overlays.base import BaseOverlay

base = BaseOverlay("base.bit")

if_id = input("Type in the interface ID used (PMODA or PMODB): ")
if if_id.upper()=='PMODA':
else:

freq = int(input("Type in the frequency/Hz of the waveform: "))
period = 1/freq
log_interval_us = 0

# Assume Channel 0 is connected to the waveform generator
sleep(3*period)

# Draw the figure
%matplotlib inline
import matplotlib.pyplot as plt
plt.plot(range(len(log)), log, 'ro')
plt.axis([0, len(log), min(log), max(log)])
plt.show()




Type in the interface ID used (PMODA or PMODB): PMODB
Type in the frequency/Hz of the waveform: 200