draw fft

main.py

from serial import *
from Tkinter import *

serialPort = "/dev/ttyUSB0"
baudRate = 115200
ser = Serial(serialPort , baudRate, timeout=0, writeTimeout=0) #ensure non-blocking

#make a TkInter Window
root = Tk()
root.wm_title("Reading Serial")

# make a scrollbar
#scrollbar = Scrollbar(root)
#scrollbar.pack(side=RIGHT, fill=Y)

# make a text box to put the serial output
#log = Text ( root, width=30, height=30, takefocus=0)
#log.pack()

canvas_width = 129
canvas_height = 255
w = Canvas(root, 
           width=canvas_width,
           height=canvas_height)
w.pack()

# attach text box to scrollbar
#log.config(yscrollcommand=scrollbar.set)
#scrollbar.config(command=log.yview)

#make our own buffer
#useful for parsing commands
#Serial.readline seems unreliable at times too
serBuffer = []

def readSerial():
    startChar = False
    while True:
        c = ser.read(1) # attempt to read a character from Serial

        #was anything read?
        if len(c) == 0:
            break
        c = ord(c)

        # get the buffer from outside of this function
        global serBuffer
        
        # check if character is a start

        if startChar:
            serBuffer.append(c)

        if c == 255:
            startChar = True

        if len(serBuffer) >= 127:
            startChar = False
            #log.insert('0.0', ''.join(map(str, serBuffer)))
            for x in xrange(len(serBuffer)):
                #w.delete("all")
                w.create_line(x, 255, x, 255-serBuffer[x], fill="#ff0000")
                w.create_line(x, 0, x, 255-serBuffer[x], fill="#ffffff")
            serBuffer = []
    
    root.after(10, readSerial) # check serial again soon


# after initializing serial, an arduino may need a bit of time to reset
root.after(100, readSerial)

root.mainloop()