# First attempt at plotting serial data
# JFDuval 20/11/2013
# ------------------------------------- #
# References/examples/credits:
# Neil Gershenfeld 'term.py' http://academy.cba.mit.edu/classes/embedded_programming/term.py
# Eli Bendersky 'matplotlib with wxPython GUIs' http://eli.thegreenplace.net/2008/08/01/matplotlib-with-wxpython-guis/
# ------------------------------------- #

import serial
import struct
import matplotlib.pyplot as plt

DEFAULT_PORT = '/dev/ttyUSB1'
DEFAULT_BAUD = 38400

ser = serial.Serial(DEFAULT_PORT, DEFAULT_BAUD, timeout = 1)

def print_byte():
	wait = ser.inWaiting()
   	if (wait != 0):
		byte = ser.read()
		print byte + '0'
		
def print_uint16():
	wait = ser.inWaiting()
   	if (wait >= 2):
		b_str = ser.read(2)
		val = struct.unpack('h',b_str)[0]
		print val
		
def get_uint16():
	wait = ser.inWaiting()
   	if (wait >= 2):
		b_str = ser.read(2)
		val = struct.unpack('h',b_str)[0]
		return val

if __name__ == '__main__':
	buf = [0] * 101
	x = range(101)
	
	plt.ion()
	fig = plt.figure()
	ax = fig.add_subplot(111)
	line1, = ax.plot(x, buf, 'r-') # Returns a tuple of line objects, thus the comma

	index = 0
	while(1):
		wait = ser.inWaiting()
   		if (wait >= 2):
			b_str = ser.read(2)
			val = struct.unpack('h',b_str)[0]
			
			#Circular buffer	
			if index < 100:
				buf[index] = val
				index = index + 1
			else:
				buf = buf[1:]
				buf.append(val)
			print val	
			
			#Refresh graph
			line1.set_ydata(buf)
			fig.canvas.draw()
			ax.axis([0, 100, min(buf), max(buf)])