electronut · May 24, 2013 07:44 · May 24, 2013
diff --git a/showdata.py b/showdata.py
@@ -0,0 +1,89 @@
+################################################################################
+# showdata.py
+#
+# Display analog data from Arduino using Python (matplotlib)
+# 
+# electronut.in
+#
+################################################################################
+
+import sys, serial
+import numpy as np
+from time import sleep
+from collections import deque
+from matplotlib import pyplot as plt
+
+# class that holds analog data for N samples
+class AnalogData:
+  # constr
+  def __init__(self, maxLen):
+    self.ax = deque([0.0]*maxLen)
+    self.ay = 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):
+    assert(len(data) == 2)
+    self.addToBuf(self.ax, data[0])
+    self.addToBuf(self.ay, data[1])
+
+# plot class
+class AnalogPlot:
+  # constr
+  def __init__(self, analogData):
+    # set plot to animated
+    plt.ion() 
+    self.axline, = plt.plot(analogData.ax)
+    self.ayline, = plt.plot(analogData.ay)
+    plt.ylim([0, 1023])
+
+  # update plot
+  def update(self, analogData):
+    self.axline.set_ydata(analogData.ax)
+    self.ayline.set_ydata(analogData.ay)
+    plt.draw()
+
+# main() function
+def main():
+  # expects 1 arg - serial port string
+  if(len(sys.argv) != 2):
+    print 'Example usage: python showdata.py "/dev/tty.usbmodem411"'
+    exit(1)
+
+ #strPort = '/dev/tty.usbserial-A7006Yqh'
+  strPort = sys.argv[1];
+
+  # plot parameters
+  analogData = AnalogData(100)
+  analogPlot = AnalogPlot(analogData)
+
+  print 'plotting data...'
+
+  # open serial port
+  ser = serial.Serial(strPort, 9600)
+  while True:
+    try:
+      line = ser.readline()
+      data = [float(val) for val in line.split()]
+      #print data
+      if(len(data) == 2):
+        analogData.add(data)
+        analogPlot.update(analogData)
+    except KeyboardInterrupt:
+      print 'exiting'
+      break
+  # close serial
+  ser.flush()
+  ser.close()
+
+# call main
+if __name__ == '__main__':
+  main()