need help with ultrasonic sensor code

[mpmm366]

Hello guys. On my raspberry pi I have a hc-sr04 ultrasonic sensor, now I want to run a sh script, when the sensor measurement is below 10cm. Here is my Code, but it doesnt work. It only executes the code when I press ctrl c. PS Iam new to python

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#!/usr/bin/env python   import time import RPi.GPIO as GPIO import os   GPIOTrigger = 23 GPIOEcho    = 24       def MesseDistanz():           GPIO.output(GPIOTrigger, True)             time.sleep(0.00001)             GPIO.output(GPIOTrigger, False)             StartZeit = time.time()     StopZeit = StartZeit             while GPIO.input(GPIOEcho) == 0:         StartZeit = time.time()            while GPIO.input(GPIOEcho) == 1:         StopZeit = time.time()             SignalLaufzeit = StopZeit - StartZeit     Distanz = (SignalLaufzeit/2) * 34350       return [Distanz, (SignalLaufzeit*1000/2)]       def main():         try:         while True:             Ergebnis = MesseDistanz()             print("Gemessene Entfernung: %.1f cm (Signallaufzeit: %.4fms)" % (Ergebnis[0], Ergebnis[1]))             time.sleep(1)            except KeyboardInterrupt:         print("Messung abgebrochen")         GPIO.cleanup()   if __name__ == '__main__':           GPIO.setmode(GPIO.BCM)             GPIO.setup(GPIOTrigger, GPIO.OUT)     GPIO.setup(GPIOEcho, GPIO.IN)             GPIO.output(GPIOTrigger, False)            main()     if 0 < 10:     os.system('. /home/pi/test.sh')

[gontajones]

After you press CTRL+C the while loop at line 46 will break and your function main() will exit. Then come this part:

1 2	if 0 < 10:     os.system('. /home/pi/test.sh')

Where your script is called.
So if you want that the script runs along with the US sensor outputs, it has to be inside the while loop.
PS: This condition of your "if" will be always True.

[mpmm366]

After you press CTRL+C the while loop at line 46 will break and your function main() will exit. Then come this part:

1 2	if 0 < 10:     os.system('. /home/pi/test.sh')

Where your script is called.
So if you want that the script runs along with the US sensor outputs, it has to be inside the while loop.
PS: This condition of your "if" will be always True.

thanks for your,what loop do you suggest me, because as far as I know there are only for while and else loops. And the problem is that the sh script can only execute one time so while would work i guess.

---

After you press CTRL+C the while loop at line 46 will break and your function main() will exit. Then come this part:

1 2	if 0 < 10:     os.system('. /home/pi/test.sh')

Where your script is called.
So if you want that the script runs along with the US sensor outputs, it has to be inside the while loop.
PS: This condition of your "if" will be always True.

thanks for your,what loop do you suggest me, because as far as I know there are only for while and else loops. And the problem is that the sh script can only execute one time so while would work i guess.

would not work*

[gontajones]

Maybe something like this...using a control flag (run_script) to avoid multiple calls of test.sh.

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def main():       try:         run_script = True         while True:             Ergebnis = MesseDistanz()             print("Gemessene Entfernung: %.1f cm (Signallaufzeit: %.4fms)" % (Ergebnis[0], Ergebnis[1]))             if Ergebnis[0] < 10 and run_script:                 os.system('/home/pi/test.sh')                 run_script = False             if Ergebnis[0] >= 10:                 run_script = True             time.sleep(1)       except KeyboardInterrupt:         print("Messung abgebrochen")         GPIO.cleanup()

[DeaD_EyE]

Polling an input will cause jitter. An event detection of a RISING edge should help.
First you assign the sent_time, then you activate the output. Ping is sending now....
After the rising edge has been detected, assign the time to an attribute and set the output to False.

The implementation of it can look like this:

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import time import RPi.GPIO as gpio     class UltraSonicSensor:       def __init__(self, send_pin, recv_pin):         self.send_pin = send_pin         self.recv_pin = recv_pin         self.ping_received = 0.0         self.setup()               def __enter__(self):         return self           def __exit__(self, *args):         gpio.cleanup()           def setup(self):         gpio.setmode(gpio.BCM)         gpio.setup(self.send_pin, gpio.OUT)         gpio.setup(self.recv_pin, gpio.IN)         # register an event         # if the event happens, the callback is called         gpio.add_event_detect(self.recv_pin, GPIO.RISING, callback=self.received, bouncetime=0)         # maybe bounctime have to be changed           def received(self, pin):         self.ping_received = time.time()         gpio.output(self.send_pin, False)           def ping(self):         """         Returns the time in seconds.         """         ping_sent = time.time()         gpio.output(self.send_pin, True)              time.sleep(0.5)         return self.ping_received - ping_sent

Code is not tested and I imported RPi.GPIO as gpio.
I don't like uppercase modules. The important methods are setup and received.

[mpmm366]

Maybe something like this...using a control flag (run_script) to avoid multiple calls of test.sh.

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def main():       try:         run_script = True         while True:             Ergebnis = MesseDistanz()             print("Gemessene Entfernung: %.1f cm (Signallaufzeit: %.4fms)" % (Ergebnis[0], Ergebnis[1]))             if Ergebnis[0] < 10 and run_script:                 os.system('/home/pi/test.sh')                 run_script = False             if Ergebnis[0] >= 10:                 run_script = True             time.sleep(1)       except KeyboardInterrupt:         print("Messung abgebrochen")         GPIO.cleanup()

thank you for your help. It works perfect. Another question. How can I add another ultrasoinc sensor to the same thing?

[gontajones]

The best way is to use the @DeaD_EyE class.

To use your code, you can do something like:

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#!/usr/bin/env python   import time import RPi.GPIO as GPIO import os   US1_GPIOTrigger = 23 US1_GPIOEcho = 24   # Change 0 to the GPIO of the US2 US2_GPIOTrigger = 0 US2_GPIOEcho = 0     def MesseDistanz(GPIOTrigger, GPIOEcho):       GPIO.output(GPIOTrigger, True)       time.sleep(0.00001)       GPIO.output(GPIOTrigger, False)       StartZeit = time.time()     StopZeit = StartZeit       while GPIO.input(GPIOEcho) == 0:         StartZeit = time.time()       while GPIO.input(GPIOEcho) == 1:         StopZeit = time.time()       SignalLaufzeit = StopZeit - StartZeit     Distanz = (SignalLaufzeit / 2) * 34350       return [Distanz, (SignalLaufzeit * 1000 / 2)]     def check_distance(distance, run_script):       if distance < 10 and run_script:         os.system('/home/pi/test.sh')         run_script = False     if distance >= 10:         run_script = True       return run_script     def main():       try:         US1_run_script = True         US2_run_script = True         while True:             Ergebnis = MesseDistanz(US1_GPIOTrigger, US1_GPIOEcho)             print("Gemessene Entfernung 1: %.1f cm (Signallaufzeit: %.4fms)" % (Ergebnis[0], Ergebnis[1]))             US1_run_script = check_distance(Ergebnis[0], US1_run_script)               Ergebnis = MesseDistanz(US2_GPIOTrigger, US2_GPIOEcho)             print("Gemessene Entfernung 2: %.1f cm (Signallaufzeit: %.4fms)" % (Ergebnis[0], Ergebnis[1]))             US2_run_script = check_distance(Ergebnis[0], US2_run_script)               time.sleep(1)       except KeyboardInterrupt:         print("Messung abgebrochen")         GPIO.cleanup()     if __name__ == '__main__':       GPIO.setmode(GPIO.BCM)       # UltraSonic 1     GPIO.setup(US1_GPIOTrigger, GPIO.OUT)     GPIO.setup(US1_GPIOEcho, GPIO.IN)     GPIO.output(US1_GPIOTrigger, False)       # UltraSonic 2     GPIO.setup(US2_GPIOTrigger, GPIO.OUT)     GPIO.setup(US2_GPIOEcho, GPIO.IN)     GPIO.output(US2_GPIOTrigger, False)       main()