Raspberry Pi based Oscilloscope unable to show graph

Question

I am trying to build Raspberry Pi based Oscilloscope.I am using raspberry Pi 3 B+ with Python 3.5 installed.I followed below link to perform this practical

https://circuitdigest.com/microcontroller-projects/raspberry-pi-based-oscilloscope/

My python script is executed successfully,as follows

reading ADS channel 0: value

But problem is unable to display graph on screen.I already installed matplotlib and drawnow packages .

I want to display graph on screen.As I am not aware about this much, so please help me to resolve this.

Answer 1

It's hard to know from the outside what exactly the problem could be. I do have some doubts about the usefulness of the drawnow package. So I would leave that one out and see if a usual animation works.

import matplotlib.pyplot as plt
from matplotlib.animation import FuncAnimation
#import numpy
# Import the ADS1x15 module.
import Adafruit_ADS1x15
# Create an ADS1115 ADC (16-bit) instance.
adc = Adafruit_ADS1x15.ADS1115()

GAIN = 1
val = [ ]

# Start continuous ADC conversions on channel 0 using the previous gain value.
adc.start_adc(0, gain=GAIN)
print('Reading ADS1x15 channel 0')

fig, ax = plt.subplots()
ax.set_ylim(-5000,5000)
ax.set_title('Osciloscope')
ax.grid(True)
ax.set_ylabel('ADC outputs')

line, = ax.plot([], 'ro-', label='Channel 0')
ax.legend(loc='lower right')

def update(cnt):
    # Read the last ADC conversion value and print it out.
    value = adc.get_last_result()
    print('Channel 0: {0}'.format(value))
    # Set new data to line
    line.set_data(list(range(len(val))), val)
    ax.relim()
    ax.autoscale_view()
    #Store values for later
    val.append(int(value))
    if(cnt>50):
        val.pop(0)

ani = FuncAnimation(fig, update, interval=500)
plt.show()