Hi Richard, maybe I'm wrong, but I think this is not related to web2py at all. Arduino boards are build to make a reset whenever the port is open/reopen so they change to "programming" state. This is made on purpose, but it's trivial to avoid it. If using an Arduino UNO board, just connecting a 10μF capacitor between RESET and GND will avoid those resets. Just remember to remove the capacitor if you need to re-program your board.
Hope this was the issue. José L. 2016-11-26 16:58 GMT+01:00 Richard Brown <[email protected]>: > I've now had chance to do some more investigation and research since my > last posting and found the following. The reason that saving files in > Web2py causes RTS to be asserted and makes my application work is that my > file 'control.py', which contains all my serial functions, includes the > lines: > > import serial > > ser=serial.Serial('/dev/ttyUSB0', 57600, timeout=1, xonxoff=0, rtscts=0) > > > If I remove/comment out the line 'ser=serial.Serial... ' then the file > save has no effect. Presumably Wb2py must be executing this line somehow as > part of it's parsing process, and saving my other file 'utilities.py' has > the same effect because it contains 'import * from control.py'. > > I have also been playing with the Pyserial functions ser.setRTS() and > ser.rts, which should force the state of RTS. I have been running these > from Python scripts in my user account and found that if reboot the > Pi, save one of the files in Web2py to force RTS low, then execute ser.rts > or ser.setRTS using my scripts, I can set RTS high or low and that state > persists. However, if I reboot the Pi and run my script *without* saving > the files in Web2py then run my scripts it only cause RTS to pulse low > momentarily, presumably while the script is running. I've tried including a > similar script within the Web2py 'modules' area, I've tried including the > set.rts commands within my serial functions, I've tried a separate function > just to include that command but nothing has done anything other than pulse > RTS until the script/function ends. I haven't tried running a routine once > at startup yet, but I'm not sure how this will be different from running > scripts 'by hand', except as far as I am aware I cannot run scripts as > the 'www-data' user as there is no login/password for that account, and I > have a strange feeling that there must be some sort of ownership issue > here. I have written/hacked scripts to run at startup to start the Web2py > Scheduler and GPIOSever but this is all a bit close to the limits of my > knowledge and ability! > > In summary, I am further forward in the sense that I understand why, if > not how, Web2py file saves make my application work, although not why > RTS gets set permanently low by this mechanism and not when the serial port > is opened at any other time, and more information on what is happening here > would be useful. I also know that there is a mechanism for changing the > state of RTS, which it must be possible to do somehow, but have no real > idea how to do it. I also now believe that keeping the port permanently > open is not necessary, provided RTS can be forced low. > > So, any clues as to how I might be able to set RTS at startup will be > gratefully received! > > Richard > > > > > > Richard > > On Friday, November 25, 2016 at 11:10:26 PM UTC, Dave S wrote: > >> >> >> On Friday, November 25, 2016 at 4:50:34 AM UTC-8, Richard Brown wrote: >>> >>> An update to this - I have done some more investigation and discovered >>> that in the 'Not Working' scenario the RTS output is mostly high but goes >>> low whilst the port is open, and in the 'Working' scenario the RTS output >>> has somehow been forced low and so stays low when the port is opened. >>> The Dongle gets reset by a high-to-low transition of RTS, so no falling >>> edge, no Reset and everything works. For reference my Dongle uses an FTDI >>> device (FT230X) and hence the FTDI driver supplied with the latest Raspbian >>> (Jessie) release. >>> >>> The question now, therefore, is how Web2py forces RTS low - either by >>> the saving of a file or when I access the index page of my Site, and How I >>> can replicate this in the Scheduler code! Using 'touch' to update the file >>> does not work, it has to be saved from within Web2py. >>> >>> Richard >>> >> >> I can't imagine how saving the file causes RTS to go low. Web2py should >> not have any reason to do anything to the serial port on its own, and >> probably doesn't even know the serial port exists (it's only concerned with >> the console). (I haven't done any serial port handling under Ubuntu, nor on >> the RaspberryPi, so I can't tell you about any special tricks such ports >> need.) >> >> You may want to investigate having a separate program that gets started >> on system startup, runs forever, and holds the serial port open all the >> time. It can check for a file existing, write the current value to the >> file, and snooze again. Your scheduled task would the create the file, >> wait briefly, and then read the file to get the current value. >> >> I do know someone with a RaspberryPi, and he's a bit of hacker, but it >> will be next week before I see him again. >> >> /dps >> >> -- > Resources: > - http://web2py.com > - http://web2py.com/book (Documentation) > - http://github.com/web2py/web2py (Source code) > - https://code.google.com/p/web2py/issues/list (Report Issues) > --- > You received this message because you are subscribed to the Google Groups > "web2py-users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. > -- Resources: - http://web2py.com - http://web2py.com/book (Documentation) - http://github.com/web2py/web2py (Source code) - https://code.google.com/p/web2py/issues/list (Report Issues) --- You received this message because you are subscribed to the Google Groups "web2py-users" group. 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