trigger event when variable equals x - python












3















I have the following script which increases the counter every time a button is pressed. When the counter reaches a certain number i.e. 10 lets say I want an event to trigger.



from RPi import GPIO
from time import sleep

clk = 25
dt = 8

GPIO.setmode(GPIO.BCM)
GPIO.setup(clk, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
GPIO.setup(dt, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)

counter = 0
clkLastState = GPIO.input(clk)

try:
while True:
clkState = GPIO.input(clk)
dtState = GPIO.input(dt)
if clkState != clkLastState:
if dtState != clkState:
counter += 1
else:
counter -= 1
print counter
clkLastState = clkState
sleep(0.01)
finally:
GPIO.cleanup()


For the purposes of an example script it might be easiest just to get it to print something on reaching the required number i.e. 'target reached'.



This question relates to an earlier post of mine here - rotary encoder script for raspberry pi using python. Rather than add to or amend that question I thought it better to break down the problem for the purposes of understanding the various components.



Many thanks










share|improve this question

























  • There is no built in way to do that - the simplest would be to check whenever you modify counter whether the new value is 10 (using a simple if) and then you'd trigger your event. See also, e.g.: stackoverflow.com/questions/6190468/…

    – UnholySheep
    Jan 1 at 12:31













  • Thanks. I should have perhaps pointed out that I found this script here - link and whilst it works as far as counting goes I don't really know how to modify it in order to get it to do what I want. Perhaps I should post on that site instead as it may be more conducive for beginners like myself anyway.

    – Nick C
    Jan 1 at 12:54











  • raspberrypi.stackexchange.com might also help

    – Patrick Artner
    Jan 1 at 13:11













  • Great thanks! Yes very apt.

    – Nick C
    Jan 1 at 13:13
















3















I have the following script which increases the counter every time a button is pressed. When the counter reaches a certain number i.e. 10 lets say I want an event to trigger.



from RPi import GPIO
from time import sleep

clk = 25
dt = 8

GPIO.setmode(GPIO.BCM)
GPIO.setup(clk, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
GPIO.setup(dt, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)

counter = 0
clkLastState = GPIO.input(clk)

try:
while True:
clkState = GPIO.input(clk)
dtState = GPIO.input(dt)
if clkState != clkLastState:
if dtState != clkState:
counter += 1
else:
counter -= 1
print counter
clkLastState = clkState
sleep(0.01)
finally:
GPIO.cleanup()


For the purposes of an example script it might be easiest just to get it to print something on reaching the required number i.e. 'target reached'.



This question relates to an earlier post of mine here - rotary encoder script for raspberry pi using python. Rather than add to or amend that question I thought it better to break down the problem for the purposes of understanding the various components.



Many thanks










share|improve this question

























  • There is no built in way to do that - the simplest would be to check whenever you modify counter whether the new value is 10 (using a simple if) and then you'd trigger your event. See also, e.g.: stackoverflow.com/questions/6190468/…

    – UnholySheep
    Jan 1 at 12:31













  • Thanks. I should have perhaps pointed out that I found this script here - link and whilst it works as far as counting goes I don't really know how to modify it in order to get it to do what I want. Perhaps I should post on that site instead as it may be more conducive for beginners like myself anyway.

    – Nick C
    Jan 1 at 12:54











  • raspberrypi.stackexchange.com might also help

    – Patrick Artner
    Jan 1 at 13:11













  • Great thanks! Yes very apt.

    – Nick C
    Jan 1 at 13:13














3












3








3


1






I have the following script which increases the counter every time a button is pressed. When the counter reaches a certain number i.e. 10 lets say I want an event to trigger.



from RPi import GPIO
from time import sleep

clk = 25
dt = 8

GPIO.setmode(GPIO.BCM)
GPIO.setup(clk, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
GPIO.setup(dt, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)

counter = 0
clkLastState = GPIO.input(clk)

try:
while True:
clkState = GPIO.input(clk)
dtState = GPIO.input(dt)
if clkState != clkLastState:
if dtState != clkState:
counter += 1
else:
counter -= 1
print counter
clkLastState = clkState
sleep(0.01)
finally:
GPIO.cleanup()


For the purposes of an example script it might be easiest just to get it to print something on reaching the required number i.e. 'target reached'.



This question relates to an earlier post of mine here - rotary encoder script for raspberry pi using python. Rather than add to or amend that question I thought it better to break down the problem for the purposes of understanding the various components.



Many thanks










share|improve this question
















I have the following script which increases the counter every time a button is pressed. When the counter reaches a certain number i.e. 10 lets say I want an event to trigger.



from RPi import GPIO
from time import sleep

clk = 25
dt = 8

GPIO.setmode(GPIO.BCM)
GPIO.setup(clk, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
GPIO.setup(dt, GPIO.IN, pull_up_down=GPIO.PUD_DOWN)

counter = 0
clkLastState = GPIO.input(clk)

try:
while True:
clkState = GPIO.input(clk)
dtState = GPIO.input(dt)
if clkState != clkLastState:
if dtState != clkState:
counter += 1
else:
counter -= 1
print counter
clkLastState = clkState
sleep(0.01)
finally:
GPIO.cleanup()


For the purposes of an example script it might be easiest just to get it to print something on reaching the required number i.e. 'target reached'.



This question relates to an earlier post of mine here - rotary encoder script for raspberry pi using python. Rather than add to or amend that question I thought it better to break down the problem for the purposes of understanding the various components.



Many thanks







python python-3.x variables raspberry-pi






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Jan 1 at 12:36









Patrick Artner

24.6k62443




24.6k62443










asked Jan 1 at 12:26









Nick CNick C

446




446













  • There is no built in way to do that - the simplest would be to check whenever you modify counter whether the new value is 10 (using a simple if) and then you'd trigger your event. See also, e.g.: stackoverflow.com/questions/6190468/…

    – UnholySheep
    Jan 1 at 12:31













  • Thanks. I should have perhaps pointed out that I found this script here - link and whilst it works as far as counting goes I don't really know how to modify it in order to get it to do what I want. Perhaps I should post on that site instead as it may be more conducive for beginners like myself anyway.

    – Nick C
    Jan 1 at 12:54











  • raspberrypi.stackexchange.com might also help

    – Patrick Artner
    Jan 1 at 13:11













  • Great thanks! Yes very apt.

    – Nick C
    Jan 1 at 13:13



















  • There is no built in way to do that - the simplest would be to check whenever you modify counter whether the new value is 10 (using a simple if) and then you'd trigger your event. See also, e.g.: stackoverflow.com/questions/6190468/…

    – UnholySheep
    Jan 1 at 12:31













  • Thanks. I should have perhaps pointed out that I found this script here - link and whilst it works as far as counting goes I don't really know how to modify it in order to get it to do what I want. Perhaps I should post on that site instead as it may be more conducive for beginners like myself anyway.

    – Nick C
    Jan 1 at 12:54











  • raspberrypi.stackexchange.com might also help

    – Patrick Artner
    Jan 1 at 13:11













  • Great thanks! Yes very apt.

    – Nick C
    Jan 1 at 13:13

















There is no built in way to do that - the simplest would be to check whenever you modify counter whether the new value is 10 (using a simple if) and then you'd trigger your event. See also, e.g.: stackoverflow.com/questions/6190468/…

– UnholySheep
Jan 1 at 12:31







There is no built in way to do that - the simplest would be to check whenever you modify counter whether the new value is 10 (using a simple if) and then you'd trigger your event. See also, e.g.: stackoverflow.com/questions/6190468/…

– UnholySheep
Jan 1 at 12:31















Thanks. I should have perhaps pointed out that I found this script here - link and whilst it works as far as counting goes I don't really know how to modify it in order to get it to do what I want. Perhaps I should post on that site instead as it may be more conducive for beginners like myself anyway.

– Nick C
Jan 1 at 12:54





Thanks. I should have perhaps pointed out that I found this script here - link and whilst it works as far as counting goes I don't really know how to modify it in order to get it to do what I want. Perhaps I should post on that site instead as it may be more conducive for beginners like myself anyway.

– Nick C
Jan 1 at 12:54













raspberrypi.stackexchange.com might also help

– Patrick Artner
Jan 1 at 13:11







raspberrypi.stackexchange.com might also help

– Patrick Artner
Jan 1 at 13:11















Great thanks! Yes very apt.

– Nick C
Jan 1 at 13:13





Great thanks! Yes very apt.

– Nick C
Jan 1 at 13:13












1 Answer
1






active

oldest

votes


















1














If you wanted to perform a (conditional) action on assignment to a value, you'd want it to be an object attribute for which you can hijack the assignment to. Overload __setattr__ method or use a property. For instance:



class C:
def __init__(self, trigger, init_val=0):
self._v = init_val
self.trigger = trigger

@property
def v(self):
return self._v

@v.setter
def v(self, value):
if value == self.trigger:
print("Trigger {} hit, perform some action.".format(value))
else:
print("Nothing to do for {}".format(value))
self._v = value

c = C(10)
while c.v < 12: # Go couple turns past the "event" to see its effect
c.v += 1


I suspect what you really are after though in these two questions is to run both loops so that you can keep counting switch events and to control spinning of the motor until latter is to stop after reaching a threshold in the former. There are more ways of achieving this, for instance threads come to mind. In the following example I've let the counter run in a separate thread and have the motor loop check how far did the counter progress:



from threading import Thread
from time import sleep

class Counter(Thread):
def __init__(self, limit):
self.value = 0
self.limit = limit
super().__init__()

def run(self):
while self.value < self.limit:
# We'd be acquiring and accumulating actual values here
sleep(1)
self.value += 1
print("Counter now at {}".format(self.value))

counter = Counter(10)
counter.start()
while counter.value < counter.limit:
print("Spinning motor")
sleep(0.5) # do actual work here
print("Stop motor")


You can combine both examples as well as run also/or motor control in its own thread. However, if both polling switch and spinning motor happen at the same frequency, it would be much simpler just to keep count and compare its value against limit within single loop. In case the motor gets started by one action and needs to be stop by another action when the limit has been reached, Just start, loop over the switch retrieval and stop it once that loop finishes.






share|improve this answer
























  • Many thanks for the detailed response. I did actually find the solution to what I wanted to achieve via the dedicated raspberry pi stack exchange forum as suggested but Patrick earlier. The link to this is here - [link] (raspberrypi.stackexchange.com/questions/92502/…). That said I accepted your answer on the basis of its thoroughness. I will also bear it mind as an alternative solution.

    – Nick C
    Jan 2 at 21:27













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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









1














If you wanted to perform a (conditional) action on assignment to a value, you'd want it to be an object attribute for which you can hijack the assignment to. Overload __setattr__ method or use a property. For instance:



class C:
def __init__(self, trigger, init_val=0):
self._v = init_val
self.trigger = trigger

@property
def v(self):
return self._v

@v.setter
def v(self, value):
if value == self.trigger:
print("Trigger {} hit, perform some action.".format(value))
else:
print("Nothing to do for {}".format(value))
self._v = value

c = C(10)
while c.v < 12: # Go couple turns past the "event" to see its effect
c.v += 1


I suspect what you really are after though in these two questions is to run both loops so that you can keep counting switch events and to control spinning of the motor until latter is to stop after reaching a threshold in the former. There are more ways of achieving this, for instance threads come to mind. In the following example I've let the counter run in a separate thread and have the motor loop check how far did the counter progress:



from threading import Thread
from time import sleep

class Counter(Thread):
def __init__(self, limit):
self.value = 0
self.limit = limit
super().__init__()

def run(self):
while self.value < self.limit:
# We'd be acquiring and accumulating actual values here
sleep(1)
self.value += 1
print("Counter now at {}".format(self.value))

counter = Counter(10)
counter.start()
while counter.value < counter.limit:
print("Spinning motor")
sleep(0.5) # do actual work here
print("Stop motor")


You can combine both examples as well as run also/or motor control in its own thread. However, if both polling switch and spinning motor happen at the same frequency, it would be much simpler just to keep count and compare its value against limit within single loop. In case the motor gets started by one action and needs to be stop by another action when the limit has been reached, Just start, loop over the switch retrieval and stop it once that loop finishes.






share|improve this answer
























  • Many thanks for the detailed response. I did actually find the solution to what I wanted to achieve via the dedicated raspberry pi stack exchange forum as suggested but Patrick earlier. The link to this is here - [link] (raspberrypi.stackexchange.com/questions/92502/…). That said I accepted your answer on the basis of its thoroughness. I will also bear it mind as an alternative solution.

    – Nick C
    Jan 2 at 21:27


















1














If you wanted to perform a (conditional) action on assignment to a value, you'd want it to be an object attribute for which you can hijack the assignment to. Overload __setattr__ method or use a property. For instance:



class C:
def __init__(self, trigger, init_val=0):
self._v = init_val
self.trigger = trigger

@property
def v(self):
return self._v

@v.setter
def v(self, value):
if value == self.trigger:
print("Trigger {} hit, perform some action.".format(value))
else:
print("Nothing to do for {}".format(value))
self._v = value

c = C(10)
while c.v < 12: # Go couple turns past the "event" to see its effect
c.v += 1


I suspect what you really are after though in these two questions is to run both loops so that you can keep counting switch events and to control spinning of the motor until latter is to stop after reaching a threshold in the former. There are more ways of achieving this, for instance threads come to mind. In the following example I've let the counter run in a separate thread and have the motor loop check how far did the counter progress:



from threading import Thread
from time import sleep

class Counter(Thread):
def __init__(self, limit):
self.value = 0
self.limit = limit
super().__init__()

def run(self):
while self.value < self.limit:
# We'd be acquiring and accumulating actual values here
sleep(1)
self.value += 1
print("Counter now at {}".format(self.value))

counter = Counter(10)
counter.start()
while counter.value < counter.limit:
print("Spinning motor")
sleep(0.5) # do actual work here
print("Stop motor")


You can combine both examples as well as run also/or motor control in its own thread. However, if both polling switch and spinning motor happen at the same frequency, it would be much simpler just to keep count and compare its value against limit within single loop. In case the motor gets started by one action and needs to be stop by another action when the limit has been reached, Just start, loop over the switch retrieval and stop it once that loop finishes.






share|improve this answer
























  • Many thanks for the detailed response. I did actually find the solution to what I wanted to achieve via the dedicated raspberry pi stack exchange forum as suggested but Patrick earlier. The link to this is here - [link] (raspberrypi.stackexchange.com/questions/92502/…). That said I accepted your answer on the basis of its thoroughness. I will also bear it mind as an alternative solution.

    – Nick C
    Jan 2 at 21:27
















1












1








1







If you wanted to perform a (conditional) action on assignment to a value, you'd want it to be an object attribute for which you can hijack the assignment to. Overload __setattr__ method or use a property. For instance:



class C:
def __init__(self, trigger, init_val=0):
self._v = init_val
self.trigger = trigger

@property
def v(self):
return self._v

@v.setter
def v(self, value):
if value == self.trigger:
print("Trigger {} hit, perform some action.".format(value))
else:
print("Nothing to do for {}".format(value))
self._v = value

c = C(10)
while c.v < 12: # Go couple turns past the "event" to see its effect
c.v += 1


I suspect what you really are after though in these two questions is to run both loops so that you can keep counting switch events and to control spinning of the motor until latter is to stop after reaching a threshold in the former. There are more ways of achieving this, for instance threads come to mind. In the following example I've let the counter run in a separate thread and have the motor loop check how far did the counter progress:



from threading import Thread
from time import sleep

class Counter(Thread):
def __init__(self, limit):
self.value = 0
self.limit = limit
super().__init__()

def run(self):
while self.value < self.limit:
# We'd be acquiring and accumulating actual values here
sleep(1)
self.value += 1
print("Counter now at {}".format(self.value))

counter = Counter(10)
counter.start()
while counter.value < counter.limit:
print("Spinning motor")
sleep(0.5) # do actual work here
print("Stop motor")


You can combine both examples as well as run also/or motor control in its own thread. However, if both polling switch and spinning motor happen at the same frequency, it would be much simpler just to keep count and compare its value against limit within single loop. In case the motor gets started by one action and needs to be stop by another action when the limit has been reached, Just start, loop over the switch retrieval and stop it once that loop finishes.






share|improve this answer













If you wanted to perform a (conditional) action on assignment to a value, you'd want it to be an object attribute for which you can hijack the assignment to. Overload __setattr__ method or use a property. For instance:



class C:
def __init__(self, trigger, init_val=0):
self._v = init_val
self.trigger = trigger

@property
def v(self):
return self._v

@v.setter
def v(self, value):
if value == self.trigger:
print("Trigger {} hit, perform some action.".format(value))
else:
print("Nothing to do for {}".format(value))
self._v = value

c = C(10)
while c.v < 12: # Go couple turns past the "event" to see its effect
c.v += 1


I suspect what you really are after though in these two questions is to run both loops so that you can keep counting switch events and to control spinning of the motor until latter is to stop after reaching a threshold in the former. There are more ways of achieving this, for instance threads come to mind. In the following example I've let the counter run in a separate thread and have the motor loop check how far did the counter progress:



from threading import Thread
from time import sleep

class Counter(Thread):
def __init__(self, limit):
self.value = 0
self.limit = limit
super().__init__()

def run(self):
while self.value < self.limit:
# We'd be acquiring and accumulating actual values here
sleep(1)
self.value += 1
print("Counter now at {}".format(self.value))

counter = Counter(10)
counter.start()
while counter.value < counter.limit:
print("Spinning motor")
sleep(0.5) # do actual work here
print("Stop motor")


You can combine both examples as well as run also/or motor control in its own thread. However, if both polling switch and spinning motor happen at the same frequency, it would be much simpler just to keep count and compare its value against limit within single loop. In case the motor gets started by one action and needs to be stop by another action when the limit has been reached, Just start, loop over the switch retrieval and stop it once that loop finishes.







share|improve this answer












share|improve this answer



share|improve this answer










answered Jan 2 at 16:37









Ondrej K.Ondrej K.

3,31671125




3,31671125













  • Many thanks for the detailed response. I did actually find the solution to what I wanted to achieve via the dedicated raspberry pi stack exchange forum as suggested but Patrick earlier. The link to this is here - [link] (raspberrypi.stackexchange.com/questions/92502/…). That said I accepted your answer on the basis of its thoroughness. I will also bear it mind as an alternative solution.

    – Nick C
    Jan 2 at 21:27





















  • Many thanks for the detailed response. I did actually find the solution to what I wanted to achieve via the dedicated raspberry pi stack exchange forum as suggested but Patrick earlier. The link to this is here - [link] (raspberrypi.stackexchange.com/questions/92502/…). That said I accepted your answer on the basis of its thoroughness. I will also bear it mind as an alternative solution.

    – Nick C
    Jan 2 at 21:27



















Many thanks for the detailed response. I did actually find the solution to what I wanted to achieve via the dedicated raspberry pi stack exchange forum as suggested but Patrick earlier. The link to this is here - [link] (raspberrypi.stackexchange.com/questions/92502/…). That said I accepted your answer on the basis of its thoroughness. I will also bear it mind as an alternative solution.

– Nick C
Jan 2 at 21:27







Many thanks for the detailed response. I did actually find the solution to what I wanted to achieve via the dedicated raspberry pi stack exchange forum as suggested but Patrick earlier. The link to this is here - [link] (raspberrypi.stackexchange.com/questions/92502/…). That said I accepted your answer on the basis of its thoroughness. I will also bear it mind as an alternative solution.

– Nick C
Jan 2 at 21:27






















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