#
# distance-direction.py
#
# Distance and Directional sensor
#    distance-direction-sensor.py serial_port
#
# Neil Gershenfeld & Ravi Tejwani
#
# (c) Massachusetts Institute of Technology 2015
#
# This work may be reproduced, modified, distributed,
# performed, and displayed for any purpose. Copyright is
# retained and must be preserved. The work is provided
# as is; no warranty is provided, and users accept all 
# liability.
#

from Tkinter import *
import serial

WINDOW = 800 # window size
filt = 0
eps = 0.1
cm_pre = 0

def idle(parent,canvas):
   global filt,eps,cm_pre
   #
   # idle routine
   #
   byte2 = 0
   byte3 = 0
   byte4 = 0
   ser.flush()
   while 1:
      #
      # find framing 
      #
      byte1 = byte2
      byte2 = byte3
      byte3 = byte4
      byte4 = ord(ser.read())
      if ((byte1 == 1) & (byte2 == 2) & (byte3 == 3) & (byte4 == 4)):
         break
   low = ord(ser.read())
   high = ord(ser.read())
   value = (256*high + low)
   filt = (1-eps)*filt+eps*value
   us = filt/8.0 # 8 MHz counter
   cm = us/58.0        
   velocity = (cm-cm_pre)*10
   cm_pre = cm
   x = int(.2*WINDOW + (.9-.2)*WINDOW*cm/50)
   y = int(.2*WINDOW + (.9-.2)*WINDOW*velocity/500)
   canvas.itemconfigure("text_cm",text="%.0f cm"%cm)
   canvas.itemconfigure("text_vel",text="%.0f vel"%velocity)
   canvas.coords('rect1',.2*WINDOW,.05*WINDOW,x,.2*WINDOW)
   canvas.coords('rect2',x,.05*WINDOW,.9*WINDOW,.2*WINDOW)  
   canvas.coords('rect3',.2*WINDOW,.25*WINDOW,y,.4*WINDOW)
   canvas.coords('rect4',y,0.25*WINDOW,.9*WINDOW,.4*WINDOW)
   canvas.update()
   parent.after_idle(idle,parent,canvas)

#
#  check command line arguments
#
if (len(sys.argv) != 2):
   print "command line: distance-direction-sensor.py serial_port"
   sys.exit()
port = sys.argv[1]
#
# open serial port
#
ser = serial.Serial(port,9600)
ser.setDTR()
#
# set up GUI
#
root = Tk()
root.title('distance-direction-sensor.py (q to exit)')
root.bind('q','exit')
canvas = Canvas(root, width=WINDOW, height=.50*WINDOW, background='white')
canvas.create_text(.1*WINDOW,.125*WINDOW,text=".33",font=("Helvetica", 24),tags="text_cm",fill="#0000b0")
canvas.create_rectangle(.2*WINDOW,.05*WINDOW,.3*WINDOW,.2*WINDOW, tags='rect1', fill='#b00000')
canvas.create_rectangle(.3*WINDOW,.05*WINDOW,.9*WINDOW,.2*WINDOW, tags='rect2', fill='#0000b0')

canvas.create_text(.1*WINDOW,.325*WINDOW,text=".33",font=("Helvetica", 24),tags="text_vel",fill="#0000b0")
canvas.create_rectangle(.2*WINDOW,.25*WINDOW,.3*WINDOW,.4*WINDOW, tags='rect3', fill='#b00000')
canvas.create_rectangle(.3*WINDOW,.25*WINDOW,.9*WINDOW,.4*WINDOW, tags='rect4', fill='#0000b0')

canvas.pack()
#
# start idle loop
#
root.after(100,idle,root,canvas)
root.mainloop()