Continuous data streaming Arduino to Python

Question

I am trying to get a Python GUI window using Tkinter to continuously display data streaming from an Arduino Uno board acting as a voltmeter. With the code I've got, the window will display one data point, and once the window gets closed, a new window opens up with the next available data point. Here's the code I've been using:

import serial
from Tkinter import *
ser = serial.Serial('/dev/tty.usbmodem621')
ser.baudrate = 9600
while 1 == 1:
    reading = ser.readline()
    root = Tk()
    w = Label(root, text = reading)
    w.pack()
    root.mainloop()

I'm using a MacBook Pro, and the pySerial package for my serial communications. How do I get the window to refresh itself?

Peter Mortensen · Accepted Answer · 2012-07-02 19:20:10Z

2

I think the problem is that you're creating a new root for every loop iteration. Try this code:

import serial
from Tkinter import *
from time import sleep
ser = serial.Serial('/dev/tty.usbmodem621')
ser.baudrate = 9600

def update():
    while 1:
        reading.set(ser.readline())
        root.update()
        sleep(1)

root=Tk()
reading = StringVar()

w = Label(root, textvariable = reading)
w.pack()

root.after(1,update)    
root.mainloop()

This sets up the "mainloop" to call the "update" function after a millisecond and uses a reference to the variable "reading" rather that the actual value of it, allowing it to be updated.

I hope this helps.

edited Jul 2, 2012 at 19:20

Peter Mortensen

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answered Jun 30, 2012 at 14:06

bradleyjkemp

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1 Comment

user1491466 Over a year ago

It helped quite a bit, thanks. The only thing that needed to be done differently was to define the variable 'reading' so I did that after defining 'update' and the code works exactly how I was expecting it to.

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