Develop Reference

How to reset input from keyboard after delay?

Simple "input" in python:
code = input("Entrer your code...")
processCode(code)
I need to ask the user for a password on a usb keyboard but without a screen (so the user doesn't see what he is typing). The text here is just for some tests. The sending is validated by the Enter key of course.
To make sure that the input is always blank when the user starts typing and sends his code, I will need to add a condition to this input.
I would need some sort of time counter which starts after each character entered and if the Enter key is not pressed for 10 seconds, the input will be automatically reset.

Here is an example of code that approximates your question. You can improve it or take inspiration from it:
import keyboard
import time
from threading import Thread
start_time = time.time()
saved_pwd = False
stop_thread = False
def dedupe(items):
seen = set()
for item in items:
if item not in seen:
yield item
seen.add(item)
def count_time():
global saved_pwd, start_time
while True:
lap_time = round(time.time() - start_time, 2)
global stop_thread
if lap_time >= 10:
print("Please Re-enter the password")
saved_pwd = True
break
elif stop_thread:
break
password = []
Thread(target=count_time).start()
while saved_pwd is False:
key = keyboard.read_key()
start_time = time.time()
if key == 'enter':
saved_pwd = True
stop_thread = True
else:
password.append(key)
print("Your pwd: ", ''.join(dedupe(password)))

How to stop 'enter spamming' in a python reaction timer

I have been trying to make a reaction timer for a project to test reaction times. It uses 'perf_counter' to record the times before and after an input to test how long it takes to press the enter key. The issue is that the enter key can be spammed which makes it seem if they have a reaction time of 0.000001 seconds. I have made a class which disables the keyboard and enables it when I want. Even in that case, people are able to sneak in extra enter presses between the disables and enables. I have attached the code below. Any ideas how to prevent enter spamming?
import time, random, msvcrt
from math import log10, floor
def round_sig(x, sig=5):
return round(x, sig-int(floor(log10(abs(x))))-1)
class keyboardDisable():
def start(self):
self.on = True
def stop(self):
self.on = False
def __call__(self):
while self.on:
msvcrt.getwch()
def __init__(self):
self.on = False
import msvcrt
disable = keyboardDisable()
disable.start()
print('When I say __GO__ you hit ENTER! This will happen 3 times. Got it?')
time.sleep(2)
print('Ready')
time.sleep(1)
print('Steady')
time.sleep(random.randint(2,5))
print('#####__GO__######')
disable.stop()
tic = time.perf_counter()
a = input()
toc = time.perf_counter()
if msvcrt.kbhit():
disable.start()
timeSpent = toc-tic
print('Your first time was '+str(timeSpent) + ' seconds')
time.sleep(1)
print('The next one is coming up.')
time.sleep(1)
print('Ready')
time.sleep(1)
print('Steady')
time.sleep(random.randint(2,5))
print('#####__GO__######')
disable.stop()
tic2 = time.perf_counter()
b = input()
toc2 = time.perf_counter()
if msvcrt.kbhit():
disable.start()
timeSpent2 = toc2-tic2
print('Your second time was '+str(timeSpent2) + ' seconds')
time.sleep(1)
print('The last one is coming up.')
time.sleep(1)
print('Ready')
time.sleep(1)
print('Steady')
time.sleep(random.randint(2,5))
print('#####__GO__######')
disable.stop()
tic3 = time.perf_counter()
c = input()
toc3 = time.perf_counter()
timeSpent3 = toc3-tic3
print('Your last time was '+str(timeSpent3) + ' seconds')
average = (timeSpent + timeSpent2 + timeSpent3)/3
numAverage = round_sig(average)
print('Your average time is '+str(numAverage) + ' seconds')

The keyboard-disabling code never really runs.
Here's a simplification of your program that uses a function to capture one reaction time and calls it thrice.
The clear_keyboard_buffer() function (that should consume all outstanding keystrokes) was borrowed from https://stackoverflow.com/a/2521054/51685 .
import time, random, msvcrt, math
def round_sig(x, sig=5):
return round(x, sig - int(math.floor(math.log10(abs(x)))) - 1)
def clear_keyboard_buffer():
while msvcrt.kbhit():
msvcrt.getwch()
def get_reaction_time():
print("Ready")
time.sleep(1)
print("Steady")
time.sleep(random.randint(2, 5))
print("#####__GO__######")
clear_keyboard_buffer()
tic = time.perf_counter()
a = input()
toc = time.perf_counter()
return toc - tic
print("When I say __GO__ you hit ENTER! This will happen 3 times. Got it?")
time1 = get_reaction_time()
print(f"Your first time was {time1} seconds")
time.sleep(1)
print("The next one is coming up.")
time2 = get_reaction_time()
print(f"Your first time was {time2} seconds")
time.sleep(1)
print("The last one is coming up.")
time3 = get_reaction_time()
print(f"Your first time was {time3} seconds")
average = (time1 + time2 + time3) / 3
print(f"Your average time is {round_sig(average)} seconds")

This solution uses a Thread to start the timer, while the main thread waits for input all the time. That way, it is possible to catch early key presses:
from threading import Thread
import random
import time
def start():
global started
started = None
time.sleep(random.randint(2,5))
print("#### GO ####")
started = time.time()
t = Thread(target=start)
print("ready...")
# start the thread and directly wait for input:
t.start()
input()
end = time.time()
if not started:
print("Fail")
else:
print(end-started)
t.join()

Python: print function hang when printing global list of objects

I'm currently writing a Python Telegram bot which is used to monitor Raspi IOs and send messages to a channel. So basically it has a function that will update a logging variable llog.
This function (logUpdate), as it's named, will remove entries that are more than 5 mins old. In it, I tried to check the content of the global variable. Upon printing, it just hangs.
This doesn't seem to block any other functionalities of the bot because I can still call out other bot commands.
I don't think it's the bot. It must be some kind of data access problems.
I attach some code snippet below:
#!usr/bin/python
##
### RF Security bot start script
##
##
### Imports
##
import telegram as tg
import telegram.ext as tgExt
import RPi.GPIO as gpio
import time
from datetime import datetime as dt
##
### Common variables
##
NULLSENSOR = 0
PRESSENSOR = 1
MAGSENSOR = 2
sensDict = {NULLSENSOR:"No sensor",
PRESSENSOR:"Pressure sensor",
MAGSENSOR:"Magnetic sensor"}
# Event class
class ev(object):
timestamp = 0
sType = NULLSENSOR
def __init__(self, ts=0, st=NULLSENSOR):
self.timestamp = ts
self.sType = st
def toString(self):
if(sType == PRESSENSOR):
return str("-> #"+timestamp.strftime('%c')+
": Pressure sensor triggered\n")
elif(sType == MAGSENSOR):
return str("-> #"+timestamp.strftime('%c')+
": Magnetic sensor triggered\n")
else:
return ""
# Report log
llog = [] # Data log
lmutex = True # Log mutex for writing
##
### Hardware configuration
##
# GPIO callbacks
def pressureCallback(channel):
global llog
global lmutex
global trigCntGlobal
global trigCntPress
ep = ev(ts=dt.now(), st=PRESSENSOR)
print("---> Pressure sensor triggered at "+
ep.timestamp.strftime("%c"))
rfSecuBot.sendMessage('#channel', "Pressure sensor "+
"triggered.")
while(not lmutex):
pass
lmutex = False
llog.insert(0, ep)
trigCntGlobal = trigCntGlobal + 1
trigCntPress = trigCntPress + 1
lmutex = True
def magneticCallback(channel):
global llog
global lmutex
global trigCntGlobal
global trigCntMag
global rfSecuBot
em = ev(ts=dt.now(), st=PRESSENSOR)
print("---> Magnetic sensor triggered at "+
em.timestamp.strftime("%c"))
rfSecuBot.sendMessage('#channel', "Magnetic sensor "+
"triggered.")
while(not lmutex):
pass
lmutex = False
llog.insert(0, em)
trigCntGlobal = trigCntGlobal + 1
trigCntMag = trigCntMag + 1
lmutex = True
# Periodic logging function
def logUpdate():
global llog
global lmutex
updTime = dt.now()
print("---> Updating log\n")
while(not lmutex):
pass
lmutex = False
for i in llog: ########### STUCK HERE
print(i.toString()) ###########
# Check log timestamps
for i in llog:
if((updTime - i.timestamp).total_seconds() > 300):
llog.remove(i)
for i in llog: ########### WAS STUCK HERE
print(i.toString()) ########### TOO
lmutex = True
print("---> Log updated\n")
# Formatting function
def logFormat():
global llog
global lmutex
logUpdate() # Asynchronous call to logUpdate to make sure
# that the log has been updated at the time
# of formatting
while(not lmutex):
pass
lmutex = False
flog = []
cnt = 0
for i in llog:
if(cnt < 10):
flog.append(i.toString())
cnt = cnt + 1
else:
break
lmutex = True
print("----> Formatted string:")
print(flog+"\n")
return flog
def listFormat():
global llog
global lmutex
logUpdate() # Asynchronous call to logUpdate to make sure
# that the log has been updated at the time
# of formatting
while(not lmutex):
pass
lmutex = False
flog = []
flog.append(" Sensors \n")
dLen = len(sensDict.keys())
if(dLen <= 1):
flog.append(sensDict.get(NULLSENSOR))
else:
sdItr = sensDict.iterkeys()
st = sdItr.next() # Had to add extra var
while(dLen > 1):
st = sdItr.next()
trigCnt = 0
for i in llog:
if(i.sType == st):
trigCnt = trigCnt + 1
if(trigCnt < 1):
pass
else:
flog.append("-> "+st+"\n")
flog.append(" No. of times tripped: "+
trigCnt+"\n")
lmutex = True
print("----> Formatted string:")
print(flog+"\n")
return flog
##
### Software configuration
##
def blist(bot, update):
print("--> List command received\n")
listString = "List of sensor trips in the last 5 minutes:\n"
listString = listString+listFormat()
print("> "+listString+"\n")
bot.sendMessage('#channel', listString)
def log(bot, update):
print("--> Log command received\n")
logString = "Log of last 10 occurrences:\n"
logString = logString+logFormat()
print("> "+logString+"\n")
bot.sendMessage('#channel', logString)
rfSecuBotUpd.start_polling(poll_interval=1.0,clean=True)
while True:
try:
time.sleep(1.1)
except KeyboardInterrupt:
print("\n--> Ctrl+C key hit\n")
gpio.cleanup()
rfSecuBotUpd.stop()
rfSecuBot = 0
quit()
break
## Callback registration and handlers are inserted afterwards
# Just in case...
print("--> Bot exiting\n")
gpio.cleanup()
rfSecuBotUpd.stop()
rfsecuBot = 0
print("\n\n\t *** EOF[] *** \t\n\n")
quit()
# EOF []
P.S. I think someone might suggest a 'class' version of this. Think it'll work?

In the toString function, I forgot to put self in front of the should-be members sType and timestamp:
def toString(self):
if(sType == PRESSENSOR):
return str("-> #"+timestamp.strftime('%c')+
": Pressure sensor triggered\n")
elif(sType == MAGSENSOR):
return str("-> #"+timestamp.strftime('%c')+
": Magnetic sensor triggered\n")
else:
return ""
Which is why the value returned was always an empty string.
Note to self: check your variables!!!
On that note, that kind of explained why it didn't seem to block the thread.

Raspberry Pi Python loop stop to work

i manipulate a sensor : HC SR04 to capture a distance.
I'm a newbie in Python and RPI. My code work, I capture distance during a time but one moment the script stop...
My code :
GPIO.setmode(GPIO.BCM)
GPIO_TRIGGER = 23
GPIO_ECHO = 24
GPIO.setup(GPIO_TRIGGER, GPIO.OUT)
GPIO.setup(GPIO_ECHO, GPIO.IN)
def main():
global state
print("ultrasonic")
while True:
print "1s second refresh.."
time.sleep(1)
i = 0
datas = []
average = 0
while i< 1:
GPIO.output(GPIO_TRIGGER, False)
time.sleep(C.time['count'])
GPIO.output(GPIO_TRIGGER, True)
time.sleep(0.00001)
GPIO.output(GPIO_TRIGGER, False)
while GPIO.input(GPIO_ECHO) == 0:
start = time.time()
while GPIO.input(GPIO_ECHO) == 1:
stop = time.time()
distance = (stop-start) * 17000
print "Distance : %.1f" % distance
average = F.getAverage(datas)
print "Average: %.1f" % average
GPIO.cleanup()
The code stop here
while GPIO.input(GPIO_ECHO) == 0:
start = time.time()
THE SOLUTION : with a sample timeout :
now = time()
while GPIO.input(self.gpio_echo) == 0 and time()-now<waitTime:
pass

I am also mucking about with this sensor. My code executes similar to yours and I need no timeout for it to work.
The one difference I can find is this:
while i< 1:
GPIO.output(GPIO_TRIGGER, False)
time.sleep(C.time['count'])
I don't know how long the sleep time is here, but it might be that that's causing the problem. If it would be similar to mine setting the Trigger to false would be directly after the setup of the in/out pins instead, and then there's a two second wait to eliminate noise. Your wait time might be lower, I can't tell. There should be no need to set the trigger to false again just before you send the pulse and, I don't know, but it might be causing a false start. I would change it to this to work similarly to mine and then remove the setting to false in the while loop.
GPIO.setup(GPIO_TRIGGER, GPIO.OUT)
GPIO.setup(GPIO_ECHO, GPIO.IN)
GPIO.output(GPIO_TRIGGER, False)
print("Waiting for sensor to settle\n")
time.sleep(2)
I'm not sure if this will solve the issue without the need for a timeout, but I don't seem to need one.
I've written a module for making an object of the sensor which then allows for some more readable scripting. I'm also quite new to python and not at all an experienced programmer so fun errors might be there somewhere, but it's here below if you want to use it or just compare code:
#! /usr/bin/python3
# dist.py this is a module for objectifying an ultrasonic distance sensor.
import RPi.GPIO as GPIO
import time
class Distancer(object):
#init takes an input of one GPIO for trigger and one for echo and creates the object,
#it searches for a calibration file in the working directory (name)Const.txt, if none
#is found it will initiate a calibration
def __init__(self, trig, cho, name):
self.trigger = trig
self.echo = cho
self.name = name
self.filename = self.name + 'Const.txt'
GPIO.setup(self.trigger, GPIO.OUT)
GPIO.setup(self.echo, GPIO.IN)
GPIO.output(self.trigger, False)
print("Waiting for sensor to calm down")
time.sleep(2)
try:
with open(self.filename, "r") as inConst:
self.theConst = int(inConst.read())
except (OSError, IOError) as e:
print("Not calibrated, initializing calibration")
self.calibrate()
with open(self.filename, "r") as inConst:
self.theConst = int(inConst.read())
#Returns the echo time
def measureTime(self):
GPIO.output(self.trigger, True)
time.sleep(0.00001)
GPIO.output(self.trigger, False)
while GPIO.input(self.echo) == 0:
pulse_start = time.time()
while GPIO.input(self.echo) == 1:
pulse_end = time.time()
pulse_duration = pulse_end - pulse_start
return pulse_duration
#Returns a distance in cm
def measure(self):
return self.measureTime() * self.theConst
#Makes you set up the sensor at 3 different distances in order to find the
#relation between pulse time and distance, it creates the file (name)Const.txt
#in the working directory and stores the constant there.
def calibrate(self):
ten = []
thirty = []
seventy = []
print("Make distance 10 cm, enter when ready")
input()
for i in range(30):
ten.append(10/self.measureTime())
time.sleep(0.2)
print("Make distance 30 cm, enter when ready")
input()
for i in range(30):
thirty.append(30/self.measureTime())
time.sleep(0.2)
print("Make distance 70 cm, enter when ready")
input()
for i in range(30):
seventy.append(70/self.measureTime())
time.sleep(0.2)
allTime = ten + thirty + seventy
theOne = 0.0
for i in range(90):
theOne = theOne + allTime[i]
theOne = theOne / 90
with open(self.filename, "w") as inConst:
inConst.write(str(round(theOne)))
#Will continually check distance with a given interval until something reaches the
#treshold (cm), takes an argument to set wether it should check for something being
#nearer(near) or farther(far) than the treashold. Returns True when treshold is reached.
def distWarn(self, nearfar, treashold):
if nearfar.lower() == "near":
while True:
if self.measure() < treashold:
return True
break
time.sleep(0.2)
if nearfar.lower() == "far":
while True:
if self.measure() > treashold:
return True
break
time.sleep(0.2)
#Will measure with a second interval and print the distance
def keepGoing(self):
while True:
try:
print(str(round(self.measure())) + ' cm')
time.sleep(1)
except KeyboardInterrupt:
print("Won't keep going")
break
I've run it with the code below to test it and everything seems to work. First time it's run it will prompt you to calibrate the sensor by putting it at different distances from something.
#! /usr/bin/python3
import RPi.GPIO as GPIO
import time
import dist as distancer
GPIO.setmode(GPIO.BOARD)
TRIG = 16
ECHO = 18
dist = distancer.Distancer(TRIG, ECHO, 'dist')
def main():
global dist
print(str(round(dist.measureTime(),5)) + ' s')
print(str(round(dist.measure())) + ' cm')
dist.distWarn('near', 10)
print('Warning, something nearer than 10 cm at ' + time.asctime( time.localtime(time.time()) ))
dist.distWarn('far', 10)
print('Warning, something further than 10 cm at ' + time.asctime( time.localtime(time.time()) ))
dist.keepGoing()
GPIO.cleanup()
print('Fin')
if __name__ == "__main__":
try:
main()
except KeyboardInterrupt:
GPIO.cleanup()
print("Exiting")
time.sleep(1)

I am pretty sure you want
while GPIO.input(GPIO_ECHO)==GPIO.LOW:
start = time.time()
while GPIO.input(GPIO_ECHO) == GPIO.HIGH:
stop = time.time()
I don't think GPIO.input naturally returns zeros or ones, you can test that though.

Not really, I think that i lost the signal, i'll try a timeout in
while GPIO.input(GPIO_ECHO)==GPIO.LOW:
start = time.time()
I think that my program wait indefinitely a signal but he stay to 0

I know this is an old question. The cause of the problem was described in this question https://raspberrypi.stackexchange.com/questions/41159/...
The solution is to add a timeout, like the OP did, to the while loops similar to this:
# If a reschedule occurs or the object is very close
# the echo may already have been received in which case
# the following will loop continuously.
count=time.time()
while GPIO.input(GPIO_ECHO)==0 and time.time()-count<0.1:
start = time.time()
...
# if an object is not detected some devices do not
# lower the echo line in which case the following will
# loop continuously.
stop = time.time()
count=time.time()
while GPIO.input(GPIO_ECHO)==1 and time.time()-count<0.1:
stop = time.time()

Python time limit

I have a homework assignment to do and I really need a solution. I have been trying to do this since yesterday but I do not know how.
Program has to generate and print a letter or a number and then a user has to type it as quickly as possible and press ENTER. The game is over after 30 secs.
Well I do not know how to put time limit to a game. I was searching through stackoverflow and I did not find anything useful. Please help me.
**Here it is what I have done so far. I tried code from the answer by SYSS.STDER, but it does not quite work because when the 30 secs are over, the game should also be over, but here in this code the game is over when I type last character.
LOOP WILL NOT STOP UNTIL IT FINISHES AND WE DISCOVER THAT WE ARE PAST OUR DEADLINE. THE TASK NEEDS TO BE INTERRUPTED IN PROGRESS AS SOON AS THE TIME ELAPSES.
max_time =30
start_time = time.time() # remember when we started
while (time.time() - start_time) < max_time:
response = "a" # the variable that will hold the user's response
c = "b" #the variable that will hold the character the user should type
score = 0
number = 0
c = random.choice(string.ascii_lowercase + string.digits)
print(c)
number = number + 1
response = input("Type a letter or a number: ") #get the user's response
if response == c and (time.time() - start_time) < max_time:
# if the response from the previous loop matches the character
# from the previous loop, increase the score.
score = score + 1

Here's my way to do it:
import string
import random
import time
response = "a" # the variable that will hold the user's response
c = "b" #the variable that will hold the character the user should type
score = 0 #the variable that will hold the user's score
start = time.time() #the variable that holds the starting time
elapsed = 0 #the variable that holds the number of seconds elapsed.
while elapsed < 30: #while less than 30 seconds have elapsed
if response == c: #if the response from the previous loop matches the character
score += 1 #from the previous loop, increase the score.
#c is a random character
c = random.choice(string.ascii_lowercase + string.digits)
print(c)
response = input("Type a letter or a number: ") #get the user's response
elapsed = time.time() - start #update the time elapsed

Since you're using Windows you can use the msvcrt.kbhit function to check for keypresses inside timing loops:
import msvcrt #### windows only ####
import os
import random
import string
import time
max_time = 15
def readch(echo=True):
"Get a single character on Windows"
ch = msvcrt.getch()
while ch in b'\x00\xe0': # special function key?
msvcrt.getch() # get keycode & ignore
ch = msvcrt.getch()
if echo:
msvcrt.putch(ch)
return ch.decode()
def elapsed_time():
global start_time
return time.time() - start_time
number = 0
score = 0
start_time = time.time() # initialize timer
while elapsed_time() < max_time:
c = random.choice(string.ascii_lowercase + string.digits)
print(c, end='')
number += 1
print("Type a letter or a number: ", end='')
while elapsed_time() < max_time:
if not msvcrt.kbhit():
time.sleep(0.1) # don't hog processor
else:
response = readch(echo=False) # get the user's response
if response == c:
print(response) # only print if correct
score += 1
break
else:
print()
print()
print("Time's up")
print("You go {} out of {}:".format(score, number))

A sample program to exit prime number function when Time limit has exceeded.
import math
from time import time
start_time = time()
max_time = 2
def prime(n):
for i in range(2, int(math.sqrt(n))):
if(time() - start_time) > max_time:
return "TLE"
if n % i == 0:
return False
return True
print(prime(3900000076541747077))

use "timeit" module available in python for better result.