power_profiling.py

#!/usr/bin/env python
 
import sys, serial
import numpy as np
from collections import deque
from matplotlib import pyplot as plt
 
# class that holds data for N samples
class DataPoll:
  # constr
  def __init__(self, maxLen):
    self.ax = deque([0.0]*maxLen)
    self.maxLen = maxLen
 
  # ring buffer
  def addToBuf(self, buf, val):
    if len(buf) < self.maxLen:
      buf.append(val)
    else:
      buf.pop()
      buf.appendleft(val)
 
  # add data
  def add(self, data):
    self.addToBuf(self.ax, data[0])
    
# plot class
class DataPlot:
  # constr
  def __init__(self, data):
    # set plot to animated
    plt.ion() 
    self.axline, = plt.plot(data.ax)
    plt.ylim([0, 20000])
 
  # update plot
  def update(self, data):
    self.axline.set_ydata(data.ax)
    plt.draw()
 
# main() function
def main():
  # expects 1 arg - serial port string
  if(len(sys.argv) != 2):
    print 'Usage: python %s /dev/ttyACM0' % sys.argv[0]
    exit(1)
 
  # strPort = '/dev/ttyACM0'
  strPort = sys.argv[1];
 
  # plot parameters
  data = DataPoll(100)
  dataPlot = DataPlot(data)
 
  print 'plotting data...'
 
  # open serial port
  ser = serial.Serial(strPort, 4000000)
  while True:
    try:
      line = ser.readline()
      c = [0]
      c[0] = float(line)
      data.add(c)
      dataPlot.update(data)
    except KeyboardInterrupt:
      print 'exiting'
      break
  # close serial
  ser.flush()
  ser.close()
 
# call main
if __name__ == '__main__':
  main()