Python3 newbie

[tony1812]

Thank you for the corrections. Base on the previous code, I try to add a global var to keep track of the number of time the loop is excuted. But I don't know why the g_loopCount in update_value is never increamented?

Also a dumb question the code comment, is it always better to use double quote rather than single? The tutorials I read seem to use them interchaneably.

import serial, time #random
from tkinter import *
from time import sleep

g_program_start_time = time.time() #new
g_loopCount = 0

#Prepare GPIO
import RPi.GPIO as GPIO
GPIO.setmode(GPIO.BOARD)
GPIO.setwarnings(False) #disable annoying warning meassages
GPIO.setup(40,GPIO.OUT)
#initial is on
#GPIO.output(40,GPIO.HIGH)

#define all functions
def read_data():
    #data = "Random number {}".format(random.randint(1, 99))
    data = ser.readline()
    #time.sleep(1)
    return data
    
def relay_on():
	GPIO.output(40,GPIO.HIGH)
	
def relay_off():
	GPIO.output(40,GPIO.LOW)

def update_value(string_var, root_window):
    g_loop_count = g_loop_count  + 1 # new
    data = read_data()
    string_var.set(data)
    g_loop_end_time = time.time() #new
    
    root_window.after(1000, updateValue, string_var, root_window)
	
#define toggle button function
def toggle():
    """
    use
    t_btn.config('text')[-1]
    to get the present state of the toggle button
    """
    if t_btn.config('text')[-1] == 'ON':
        t_btn.config(text='OFF')
        relay_on()
        #GPIO.output(40,GPIO.LOW)
        
    else:
        t_btn.config(text='ON')
        relay_off()
        #GPIO.output(40,GPIO.HIGH)

root = Tk()
root.geometry("800x400+0+0")
ser = serial.Serial('/dev/ttyUSB0', 9600)
var = String_var()
var.set('Gethar Sensor data.')

dataLabel = Label(root, textvariable = var)
dataLabel.place(x=300, y=300)

g_program_start_time_Label = Label(root, text = "program start at: " + str(hash(g_program_start_time)))
g_program_start_time_Label.place(x=300, y=250)

loop_count_Label = Label(root, text = "loop count is: " + str(g_loop_count))
loop_count_Label.place(x=300, y=275)

# Add a toggle button
t_btn = Button(root, text = "On/Off", command=toggle)
t_btn.place(x=380, y=350)


root.after(1000, update_value, var, root)

root.mainloop()
#END