while 循环无限运行。无法使用计时器终止 while 循环

Question

我正在尝试打开和关闭来自 Python 的电磁阀。可以在实验开始之前使用信息框定义此切换模式。例如，我可以定义可以发生多少次切换（切换次数）或将发生多长时间（以秒为单位的切换时间）。我向 Arduino 发送两个字节，一个用于通道选择（1 到 8），第二个用于状态（0 或 1）。

切换次数完美。在 while 循环中，我给出了指令 myTime > 0 并且在每次切换期间我将它减一。因此 while 循环将运行直到 myTime 或 Number of toggles 变为零。

但是，当我试图从信息框中输入时间时，它变成了一个无限循环。我可以从信息框中给出时间并将其添加到 time.time() 并尝试在 while 循环中比较它，并希望在 time.time() 变得大于所需时间时终止循环。

如何确保我可以使用这两个条件终止 while 循环？

Python code: 

from __future__ import absolute_import, division, print_function
import serial
from time import sleep
import struct
from psychopy import core, data, event, gui, visual 
import time


try:
    arduino = serial.Serial('COM8',19200)
    sleep(2)
    print("Connection to " + 'COM8' + " established succesfully!\n")
except Exception as e:
    print(e)

global command

## create a DlgFromDict
info = {'Observer':'jwp', 'Channel':['1','2','3','4','5','6','7','8'],
    'BreathingCycle':4, 'Timer': 0, 'ExpVersion': 1.1, 'Debug Mode': True}
infoDlg = gui.DlgFromDict(dictionary=info, title='TestExperiment',
    order=['ExpVersion', 'Observer'],
    tip={'Observer': 'trained visual observer, initials'},
    fixed=['ExpVersion'])  

myChannel = info['Channel']
myTime = info ['BreathingCycle']
myTimer = info ['Timer']



win = visual.Window(fullscr=True, size=(1536, 864), monitor='laptop') 
#TODO: handle in a different way the screen resolution

instruction1 = visual.TextStim(win, text=u"""Valve on!""")

instruction2 = visual.TextStim(win, text=u"""Valve off!""")

instruction3 = visual.TextStim(win, text=u"""Thank you!""")


if infoDlg.OK:

Mytimer = time.time() + myTimer

while (myTime > 0 or time.time() < Mytimer):     

        if  myChannel == '1': 
            if u'i' in event.waitKeys():
                command = arduino.write(struct.pack(u'>H',513)) 
                myTime = myTime - 1
                instruction1.draw() 
                win.flip()
            if u'e' in event.waitKeys():
                command = arduino.write(struct.pack(u'>H',512))
                myTime = myTime - 1
                instruction2.draw()
                win.flip()
        elif  myChannel == '2': 
                if u'i' in event.waitKeys():
                    command = arduino.write(struct.pack(u'>H',257)) 
                    myTime = myTime - 1
                    instruction1.draw() 
                    win.flip()
                if u'e' in event.waitKeys():
                    command = arduino.write(struct.pack(u'>H',256))
                    myTime = myTime - 1
                    instruction2.draw()
                    win.flip()
        elif  myChannel == '3': 
                if u'i' in event.waitKeys():
                    command = arduino.write(struct.pack(u'>H',2049)) 
                    myTime = myTime - 1
                    instruction1.draw() 
                    win.flip()
                if u'e' in event.waitKeys():
                    command = arduino.write(struct.pack(u'>H',2048))
                    myTime = myTime - 1
                    instruction2.draw()
                    win.flip()
        elif  myChannel == '4': 
                if u'i' in event.waitKeys():
                    command = arduino.write(struct.pack(u'>H',1025)) 
                    myTime = myTime - 1
                    instruction1.draw() 
                    win.flip()
                if u'e' in event.waitKeys():
                    command = arduino.write(struct.pack(u'>H',1024))
                    myTime = myTime - 1
                    instruction2.draw()
                    win.flip()
        elif  myChannel == '5': 
                if u'i' in event.waitKeys():
                    command = arduino.write(struct.pack(u'>H',4097)) 
                    myTime = myTime - 1
                    instruction1.draw() 
                    win.flip()
                if u'e' in event.waitKeys():
                    command = arduino.write(struct.pack(u'>H',4096))
                    myTime = myTime - 1
                    instruction2.draw()
                    win.flip()
        elif  myChannel == '6': 
                if u'i' in event.waitKeys():
                    command = arduino.write(struct.pack(u'>H',8193)) 
                    myTime = myTime - 1
                    instruction1.draw() 
                    win.flip()
                if u'e' in event.waitKeys():
                    command = arduino.write(struct.pack(u'>H',8192))
                    myTime = myTime - 1
                    instruction2.draw()
                    win.flip()
        elif  myChannel == '7': 
                if u'i' in event.waitKeys():
                    command = arduino.write(struct.pack(u'>H',32769)) 
                    myTime = myTime - 1
                    instruction1.draw() 
                    win.flip()
                if u'e' in event.waitKeys():
                    command = arduino.write(struct.pack(u'>H',32768))
                    myTime = myTime - 1
                    instruction2.draw()
                    win.flip()
        elif  myChannel == '8': 
                if u'i' in event.waitKeys():
                    command = arduino.write(struct.pack(u'>H',16385)) 
                    myTime = myTime - 1
                    instruction1.draw() 
                    win.flip()
                if u'e' in event.waitKeys():
                    command = arduino.write(struct.pack(u'>H',16384))
                    myTime = myTime - 1
                    instruction2.draw()
                    win.flip()

win.close ()  
arduino.close()

Answer 1

我找到了解决方案，因为有一些函数 event.waitKeys() 基本上是无限期地等待一个键，这就是为什么 time.time() < Mytimer 条件不可用核实。我不得不在 event.waitKeys() 中给出最长等待时间。

while 循环无限运行。无法使用计时器终止 while 循环

The while loop runs infinite. It is not possible to terminate while loop using timer

python-2.7

arduino-uno