arduinoReaderPlotter.py

''' This is adapted from an example I found somewhere, if anyone knows what it is let me know and I'll credit the original '''

import threading
import time
import math
import gobject
import matplotlib
matplotlib.use('GTKAgg')
import matplotlib.pyplot as plt
import random
import serial
import Queue


class Arduino(threading.Thread):
	def __init__(self, queue):
		''' Threaded arduino reader '''
		threading.Thread.__init__(self)
		try:
			self.baudRate = 115200
			self.ser = serial.Serial("/dev/ttyUSB0", self.baudRate)
			print 'initiated arduino'
		except:
			# Couldn't connect, generated random data
			self.connected = False
			print "Using random data"
		self.queue = queue
		
	def run(self):
		while True:
			if self.connected:
				self.ser.flushInput()
				self.ser.flushOutput()
				while True:
					if self.ser.inWaiting() > 0:
						'''Parse data here, put it in the queue'''

						datax = ser.readline()
						# NEEDS to be ints/floats to plot!
						self.queue.put(datax)
			else:
				self.queue.put(random.randint(0,255))
				time.sleep(0.5)

def update():
	''' Called every updateDelay milliseconds 
	grabs data from the queue, plots the data'''

	global windowLength, q, a, data, f

	# Clear our A axis so we don't see everything that we plotted before, but that means we'll have to
	# remake our labels
	a.cla()
	a.set_xlabel("Time (Seconds)")
	a.set_ylabel("Value")
	
	while not q.empty():
		data.append(q.get())
		data.pop(0) # As we initialized our data array, we need to pop off the first entries

	x, = a.plot(data, 'b-')

	# Auto adjust our plot for our data (just Y)
	min_t = min(data)
	max_t = max(data)
	a.axis([0, windowLength, min_t-10,max_t+10])

	f.canvas.draw_idle()

	return True

if __name__ == '__main__':
	# time in milliseconds to wait before grabbing new data
	updateDelay = 100

	# Make a queue so we can do the data processing in one thread (reading from arduino) and plot in another
	q = Queue.Queue()

	# Start the arduino - tries to connect on /dev/ttyUSBX (linux), may need to change port for windows 
	arduino = Arduino(q)
	# Start the thread
	arduino.start()

	f = plt.figure()
	a = f.add_subplot(111)
	a.grid(True)

	windowLength = 101

	data = [0 for x in range(windowLength)]

	f.suptitle("Live Plot")

	gobject.timeout_add(updateDelay, update)

	plt.show()