scope-test.py

#!/usr/bin/env python3

import numpy as np
import matplotlib.pyplot as P
import matplotlib.widgets as W
import os,sys,serial,time

for d in ("USB0", "USB1", "ACM0", "ACM1", "FAIL"):
  if d == "FAIL": sys.exit("Can not find serial port")
  dev = "/dev/tty" + d
  if os.path.exists(dev): break

serial.Serial(dev, 9600, timeout=2).close()     # Bugfix Olimex CH340 chip
ser = serial.Serial(dev, 500000, timeout=2)     # 115200 baud
time.sleep(2)                                   # Arduino starts in ~1.6s


def analyse(y):
  m, s = 0, 0
  for n in range(len(y)):
    if   m == 0 and y[n] < 2.5: m, s = 1, 0
    elif m == 1 and y[n] > 2.5: m, s = 2, n
    elif m == 2 and y[n] < 2.5: m, s = 3, s
    elif m == 3 and y[n] > 2.5: m, s = 4, n - s
  period = (14.0 / afreq) + 4e-6
  if m == 4:
    freq =  int(1.0 / (period * s))
    ax.set_title("Waveform freq: " + str(freq) + " Hz" )
  return period

def showgraph(*args):
  ser.flushInput()                              # flush input just in case
  ser.write(b"w\n")                             # send string + newline
  txt = ser.readline(5000).decode()             # read string + newline
  ytxt=txt.split(',')                           # split into list of strings
  del ytxt[-1]                                  # delete newline
  ax.cla()
  y = [ float(n) * 5 / 1024 for n in ytxt]
  period = analyse(y)
  x = [ n * period * 1000 for n in range(len(y))]
  ax.set_xlabel("Time (ms)")
  ax.set_ylabel("Voltage (V)")
  ax.plot(x,y,lw=2)
  P.draw()

fig, ax = P.subplots()
P.subplots_adjust(left=0.2)         # leave gap for buttons
axcolor = 'lightgoldenrodyellow'

def butfunc(butname):
  global act
  act = butname
  if act in ["Single", "Repeat"]: timer.start()

butlist = ["Stop", "Repeat", "Single"]
but = list(butlist)
for b in range(len(butlist)):
  butshape = P.axes([0.01, 0.1 + b/17.5, 0.12, 0.05])
  but[b] = W.Button(butshape, butlist[b], color=axcolor)
  but[b].on_clicked(lambda event, butname=butlist[b]: butfunc(butname))

def afunc(label):
  global afreq
  afreq = int(label) * 1000
  ser.flushInput()
  anumber = str(aname.index(label) + 2)
  ser.write(("a" + anumber + "\n").encode())
  discard = ser.readline(5000)

aname = ("4000", "2000", "1000", "500", "250", "125")
ashape = P.axes([0.01, 0.65, 0.12, 0.2], facecolor=axcolor)
ashape.set_title("Clock to\nADC (kHz)")
aradio = W.RadioButtons(ashape, aname, active=2)
aradio.on_clicked(afunc)
afreq = 1000000

def fqfunc(label):
  ser.flushInput()
  fqnumber = str(fname.index(label) + 1)
  ser.write(("s" + fqnumber + "\n").encode())
  discard = ser.readline(5000)

fname = ("31250", "3906", "976", "488", "244", "122", "30.5")
fshape = P.axes([0.01, 0.32, 0.12, 0.22], facecolor=axcolor)
fshape.set_title("Signal\nout (Hz)")
fradio = W.RadioButtons(fshape, fname, active=4)
fradio.on_clicked(fqfunc)

def tfunc():
  if act != "Stop":  showgraph()
  if act == "Repeat": timer.start()

act = "Single"
timer = fig.canvas.new_timer(interval=10)
timer.add_callback(tfunc)
timer.single_shot = True
timer.start()
P.show()