Re: [Dorset] Python Function Appears to be Entered Twice
On Tuesday, 14 March 2017 18:38:37 GMT Ralph Corderoy wrote: > OK, though I think it's a software problem. Out of interest, what kind > of cabling and runs are we talking? It is plain wire and it was about 40 cm from the switches to the pull-downs board (via a D-Type). Then there is about 4 to 5 cm between the resistors and the GPIO pins. The capacitors (0,1 uF) are connected across each switch contact. > > pi@raspberrypi:~/WMT/Code/Minster_Functions $ sudo strace -tt -o > > strace.out -f \> > > > -e trace=process -e trace=file -e trace=desc \ > > > > > > changerings3.py > > > > strace: Can't stat 'changerings3.py': No such file or directory > > File changerings3.py isn't in the current directory. But it was. The path in the prompt matches the one below that was found, but wouldn't execute. Also, I used tab completion to confirm that I'd got the right filename. > Success! It found the file, but it isn't executable. Why? I didn't do anything special to your example and that did execute, so why won't mine? However, after I made my file executable strace worked. So I say again, how come yours worked when I didn't make it executable? !! (I've never made any of my Python files executable because I usually launch them from within IDLE or by executing: python myfile.py (This may well have changed by the time I get round to deploying this software to launch at boot-up.) > I think even if changerings3.py was made executable, it would still have > problems because it's running env(1) with `python 2.7' as arguments, and > that would run python(1), which might be version 2 or 3, and pass it > `2.7 /home/terry/WMT/Code/Minster_Functions/changerings3.py'. It > wouldn't like 2.7 as the script to run. No. It did work. > sudo strace -tt -o strace.out -f \ > -e trace=process -e trace=file -e trace=desc \ > python2.7 test-callback.py See http://www.hadrian-way.co.uk/Misc/strace.out -- Terry Coles -- Next meeting: Bournemouth, Tuesday, 2017-04-04 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] Python Function Appears to be Entered Twice
Hi Terry, > so I only got onto all this again this afternoon. No need to explain. I'm used to email threads having days between posts. :-) > Clive has shortened the cabling considerably and we've removed the > outer plastic sheath and teased out the wires on all of the cable runs > to reduce the cross-talk to a minimum. OK, though I think it's a software problem. Out of interest, what kind of cabling and runs are we talking? > /usr/lib/python3/dist-packages/RPi.GPIO-0.6.3.egg-info > This ties in with the version in the Raspbian Package Manager. And the latest tar file of source I could find on the SourceForge site. > I've put the complete script, cut-down as you suggested, in: > http://www.hadrian-way.co.uk/Misc/changerings3.py.txt Very handy, thanks. > > sudo strace -tt -o strace.out -f \ > > -e trace=process -e trace=file -e trace=desc \ > > your-python-script.py > > pi@raspberrypi:~/WMT/Code/Minster_Functions $ sudo strace -tt -o > strace.out -f \ > > -e trace=process -e trace=file -e trace=desc \ > > changerings3.py > strace: Can't stat 'changerings3.py': No such file or directory File changerings3.py isn't in the current directory. > pi@raspberrypi:~/WMT/Code/Minster_Functions $ sudo strace -tt -o > strace.out -f -e trace=process -e trace=file -e trace=desc changerings3.py > strace: Can't stat 'changerings3.py': No such file or directory Ditto. (Though you have removed the backslashes correctly.) > pi@raspberrypi:~/WMT/Code/Minster_Functions $ sudo strace -tt -o > strace.out -f -e trace=process -e trace=file -e trace=desc > ~/WMT/Code/Minster_Functions/changerings3.py > strace: exec: Permission denied Success! It found the file, but it isn't executable. > pi@raspberrypi:~/WMT/Code/Minster_Functions $ sudo strace -tt -o > strace.out -f \ > > -e trace=process -e trace=file -e trace=desc \changerings3.py > strace: Can't stat 'changerings3.py': No such file or directory Now you're guessing. :-) That still looks for file `./changerings3.py'. I think even if changerings3.py was made executable, it would still have problems because it's running env(1) with `python 2.7' as arguments, and that would run python(1), which might be version 2 or 3, and pass it `2.7 /home/terry/WMT/Code/Minster_Functions/changerings3.py'. It wouldn't like 2.7 as the script to run. And when the script is run, it sets up the GPIO requirements and then exits. There's nothing to make the main thread hang around whilst your dalliance with the GPIO thread occurs. Here's your test script with even more lines deleted. It should run with python2.7 test-callback.py without needing to make it executable. Hopefully, you can exhibit the problem with it. Then trigger the problem again under strace. sudo strace -tt -o strace.out -f \ -e trace=process -e trace=file -e trace=desc \ python2.7 test-callback.py 8< cut here #! /usr/bin/env python2.7 import time import RPi.GPIO as GPIO def main(): print GPIO.VERSION GPIO.setmode(GPIO.BCM) # Pin numbering scheme. for pin in (22,): GPIO.setup(pin, GPIO.IN) GPIO.add_event_detect(pin, GPIO.RISING, callback=handle_event, bouncetime=300) print 'main sleeping' time.sleep(42) print 'main done' def handle_event(gpio): print 'enter', gpio time.sleep(3) print 'exit', gpio main() 8< cut here Cheers, Ralph. -- Next meeting: Bournemouth, Tuesday, 2017-04-04 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] Python Function Appears to be Entered Twice
On Tuesday, 14 March 2017 17:21:12 GMT Stephen Wolff wrote: > >> What's the line look like that registers your callback? > > > > I've put the complete script, cut-down as you suggested, in: > > http://www.hadrian-way.co.uk/Misc/changerings3.py.txt > > > >> Taking the stripped down, simple as possible, test program, have it do > >> the time.sleep(2) and not import the subprocess module. Run it under > >> strace(1) to capture its interactions with the kernel. (The Python > >> module is a poorly documented black box there to provide a "helpful" > >> abstraction; we're now trying to see through it to understand its > >> behaviour. :-) > >> > >> sudo strace -tt -o strace.out -f \ > >> > >> -e trace=process -e trace=file -e trace=desc \ > >> your-python-script.py > > Can you put the ‘add_switch_events()’ under an if __name__ == ‘main’: > > see > > - http://stackoverflow.com/questions/4041238/why-use-def-main > > could it be that the script is called each time the file is imported? So I rewrote the last line of the script as: if __name__ == '__main__': add_switch_events() but the code didn't do anything! -- Terry Coles -- Next meeting: Bournemouth, Tuesday, 2017-04-04 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] Python Function Appears to be Entered Twice
>> What's the line look like that registers your callback? > > I've put the complete script, cut-down as you suggested, in: > > http://www.hadrian-way.co.uk/Misc/changerings3.py.txt > >> Taking the stripped down, simple as possible, test program, have it do >> the time.sleep(2) and not import the subprocess module. Run it under >> strace(1) to capture its interactions with the kernel. (The Python >> module is a poorly documented black box there to provide a "helpful" >> abstraction; we're now trying to see through it to understand its >> behaviour. :-) >> >> sudo strace -tt -o strace.out -f \ >> -e trace=process -e trace=file -e trace=desc \ >> your-python-script.py > Can you put the ‘add_switch_events()’ under an if __name__ == ‘main’: see - http://stackoverflow.com/questions/4041238/why-use-def-main could it be that the script is called each time the file is imported? -- Next meeting: Bournemouth, Tuesday, 2017-04-04 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
Re: [Dorset] Python Function Appears to be Entered Twice
Ralph, It's been a while since you wrote. Yesterday was model town day + shopping and this morning, I had other errands to run. so I only got onto all this again this afternoon. In the meantime, Clive has shortened the cabling considerably and we've removed the outer plastic sheath and teased out the wires on all of the cable runs to reduce the cross-talk to a minimum. I monitored the 'Change Runs On' GPIO pin with my (fairly limited) Arduino based scope and saw a little bounce when the switch was depressed (less than 1 ms) and no bounce when it was released (as you would expect). Of course, a very fast edge or ringing wouldn't show up on that scope, although I have been offered the loan of a real one, if it would help. On Sunday, 12 March 2017 18:10:45 GMT Ralph Corderoy wrote: > What version is the GPIO Python module you're using? If it's not > obvious, then there may be a GPIO.VERSION string that can be printed > from Python. pi@raspberrypi:~ $ find /usr/ | grep -i RPi.GPIO /usr/share/doc/python-rpi.gpio /usr/lib/python3/dist-packages/RPi.GPIO-0.6.3.egg-info This ties in with the version in the Raspbian Package Manager. > What's the line look like that registers your callback? I've put the complete script, cut-down as you suggested, in: http://www.hadrian-way.co.uk/Misc/changerings3.py.txt > Taking the stripped down, simple as possible, test program, have it do > the time.sleep(2) and not import the subprocess module. Run it under > strace(1) to capture its interactions with the kernel. (The Python > module is a poorly documented black box there to provide a "helpful" > abstraction; we're now trying to see through it to understand its > behaviour. :-) > > sudo strace -tt -o strace.out -f \ > -e trace=process -e trace=file -e trace=desc \ > your-python-script.py I couldn't get that to work. See what I tried: pi@raspberrypi:~/WMT/Code/Minster_Functions $ sudo strace -tt -o strace.out - f \> -e trace=process -e trace=file -e trace=desc \ > changerings3.py strace: Can't stat 'changerings3.py': No such file or directory pi@raspberrypi:~/WMT/Code/Minster_Functions $ sudo strace -tt -o strace.out -f -e trace=process -e trace=file -e trace=desc changerings3.py strace: Can't stat 'changerings3.py': No such file or directory pi@raspberrypi:~/WMT/Code/Minster_Functions $ sudo strace -tt -o strace.out -f -e trace=process -e trace=file -e trace=desc ~/WMT/Code/Minster_Functions/ changerings3.py strace: exec: Permission denied pi@raspberrypi:~/WMT/Code/Minster_Functions $ sudo strace -tt -o strace.out -f \ > -e trace=process -e trace=file -e trace=desc \changerings3.py strace: Can't stat 'changerings3.py': No such file or directory I'm not sure why it can't find the script; I used tab completion to get the name right. -- Terry Coles -- Next meeting: Bournemouth, Tuesday, 2017-04-04 20:00 Meets, Mailing list, IRC, LinkedIn, ... http://dorset.lug.org.uk/ New thread: mailto:dorset@mailman.lug.org.uk / CHECK IF YOU'RE REPLYING Reporting bugs well: http://goo.gl/4Xue / TO THE LIST OR THE AUTHOR
