You're welcome. If you have more questions just ask. On Thu, Jul 14, 2016 at 9:11 PM, Raul Piper <raulpbloo...@gmail.com> wrote:
> Hello William, > Thankyou very much for jotting down all the relevant example amidst your > busy schedule.I am really grateful to you.I will check this.This example > looks far simpler to me. > Rgds, > Rp > > On Friday, July 15, 2016 at 2:26:00 AM UTC+5:30, William Hermans wrote: >> >> By the way. I'm not familiar with the C++ fstream object. But this person >> is not doing any error checking . . . >> >> On Thu, Jul 14, 2016 at 1:48 PM, William Hermans <yyr...@gmail.com> >> wrote: >> >>> Ok turns out I do not have to write an example. After a quick google >>> search I found a very good simple example on stackoverflow: >>> http://stackoverflow.com/questions/21198933/how-to-control-beaglebone-gpio-pins >>> >>> So. . . this is a very good example that shows how one would, or could >>> wrap the gpio sysfs files. This: >>> >>> fs.open("/sys/kernel/debug/omap_mux/gpmc_ad4"); >>>> fs << "7"; >>>> >>>> May be incorrect for current kernel / file system structure, but I can >>> tell you what this bit of code is going. It's simply muxing the pin he / >>> she want to control in code. 0x7 == pin mux for GPIO mode. So you( we ) can >>> either figure how do do this with modern debian images, or "we" could >>> simply mu our pins with config-pin( universal IO ) or device tree overlay. >>> >>> Personally, since I've been experimenting with Charles' universal-io >>> overlays and config-pin recently, and in my spare time. I'm favoring that >>> lately. Also, that script is very easily wrapped in code as well. Anyway, >>> once the pin it muxed for the correct mode, the rest of that code would( >>> should ) simply work. >>> >>> fs.open("/sys/class/gpio/export"); >>>> fs << "32"; >>>> fs.close(); >>>> >>> >>> This is exactly as if you echo "32" into /sys/class/gpio/export. Which >>> exports the pin. >>> >>> fs.open("/sys/class/gpio/gpio32/direction"); >>>> fs << "out"; >>>> fs.close(); >>> >>> >>> Exactly like echoing "out" into /sys/class/gpio/gpio32/direction. Which >>> configures the pin as output. >>> >>> fs.open("/sys/class/gpio/gpio32/value"); >>>> fs << "1"; >>>> fs.close(); >>>> >>>> >>> Exactly the same as echoing "1" into /sys/class/gpio/gpio32/value. >>> Which makes the pin output, and high. >>> >>> Any further questions ? >>> >>> On Thu, Jul 14, 2016 at 11:20 AM, William Hermans <yyr...@gmail.com> >>> wrote: >>> >>>> OK, I'm still a little busy, but I should have something example wise >>>> in a couple hours. >>>> >>>> On Thu, Jul 14, 2016 at 1:00 AM, William Hermans <yyr...@gmail.com> >>>> wrote: >>>> >>>>> You only need to toggle gpio ? How fast do you need it to be ? That >>>>> code is far to complex, and uses threading, as well as callbacks for some >>>>> odd reason. Threaded code can have performance overhead, and callbacks can >>>>> cause problems on the stack if you're not careful. >>>>> >>>>> You would be better off writing your own wrapper code. You could >>>>> either wrap the sysfs gpio files directly. Or if you wished you could wrap >>>>> config-pin from universal io. >>>>> >>>>> Anyway, it's getting late here so perhaps tomorrow I'll write up a >>>>> quick example, that is far less code than D.R. Molloy's . . . uh . >>>>> ..library ? The thing is, the sysfs directory / file structure is already >>>>> there and functional. Why would anyone need to write so much code to >>>>> encapsulate it ? *shrug* >>>>> >>>>> On Wed, Jul 13, 2016 at 10:02 PM, Raul Piper <raulpb...@gmail.com> >>>>> wrote: >>>>> >>>>>> Attached. >>>>>> One is the cpp code and other is the bash script. >>>>>> cpp code uses the GPIO class from the attached GPIO.7z . >>>>>> >>>>>> >>>>>> On Thursday, July 14, 2016 at 9:50:45 AM UTC+5:30, William Hermans >>>>>> wrote: >>>>>>> >>>>>>> Let's put it this way. No code, no help . . . >>>>>>> >>>>>>> On Wed, Jul 13, 2016 at 9:19 PM, William Hermans <yyr...@gmail.com> >>>>>>> wrote: >>>>>>> >>>>>>>> >>>>>>>> #code2 >>>>>>>> //create an instance of gpio41 >>>>>>>> //set direction as OUT >>>>>>>> //set value as 1 >>>>>>>> usleep(100000); >>>>>>>> //set value 0 >>>>>>>> >>>>>>>> Output : Toggle doesnt happens >>>>>>>> >>>>>>>> Whats this ? This is not code. At best it's comments, and usleep(). >>>>>>>> >>>>>>>> >>>>>>>> On Wed, Jul 13, 2016 at 9:02 PM, Raulp <imsaura...@gmail.com> >>>>>>>> wrote: >>>>>>>> >>>>>>>>> OK let em explain a bit more : >>>>>>>>> #code 1 >>>>>>>>> sudo echo 41 > export >>>>>>>>> cd gpio41 >>>>>>>>> sudo chmod 666 direction >>>>>>>>> sudo chmod 666 value >>>>>>>>> sudo echo out > direction >>>>>>>>> sudo echo 1 > value >>>>>>>>> sleep 1 >>>>>>>>> sudo echo 0 > value >>>>>>>>> >>>>>>>>> Output : Toggle on the GPIO 41 >>>>>>>>> >>>>>>>>> >>>>>>>>> #code2 >>>>>>>>> //create an instance of gpio41 >>>>>>>>> //set direction as OUT >>>>>>>>> //set value as 1 >>>>>>>>> usleep(100000); >>>>>>>>> //set value 0 >>>>>>>>> >>>>>>>>> Output : Toggle doesnt happens >>>>>>>>> >>>>>>>>> >>>>>>>>> Now the output I am referring to is the functioning of the >>>>>>>>> hardware I have used.(ignore toggling , it happens anyway using the >>>>>>>>> code#2) >>>>>>>>> >>>>>>>>> >>>>>>>>> Or does your code simply open, and use the file descriptors >>>>>>>>> without any error checking what so ever ? >>>>>>>>> >> I dont use error codes to check , but I have seen in the >>>>>>>>> oscilloscope that the signal transition is happening according to my >>>>>>>>> code. >>>>>>>>> >>>>>>>>> -Rp >>>>>>>>> >>>>>>>>> >>>>>>>>> On Wednesday, July 13, 2016 at 8:52:30 PM UTC+5:30, William >>>>>>>>> Hermans wrote: >>>>>>>>>> >>>>>>>>>> When I try to do the same using a user space C application I dont >>>>>>>>>>> get the expected response.I am running this app as sudo'er and I >>>>>>>>>>> have >>>>>>>>>>> oscilloscope'd the timings of HIGH/LOW levels of the GPIOs and >>>>>>>>>>> compared it >>>>>>>>>>> with that of the manually writing procedure of GPIOS. The waveform >>>>>>>>>>> and the >>>>>>>>>>> timing diagrams almost matches (95%) >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> I'm not exactly sure what you saying here . . . However, in code >>>>>>>>>> are you actually checking for errors, and error codes. Or does your >>>>>>>>>> code >>>>>>>>>> simply open, and use the file descriptors without any error >>>>>>>>>> checking what >>>>>>>>>> so ever ? >>>>>>>>>> >>>>>>>>>> Seeing the code would probably help a lot. >>>>>>>>>> >>>>>>>>>> On Wed, Jul 13, 2016 at 2:41 AM, Raulp <imsaura...@gmail.com> >>>>>>>>>> wrote: >>>>>>>>>> >>>>>>>>>>> I have interfaced a hardware using the 5 Gpios on BBB.I can talk >>>>>>>>>>> to this device using GPIOs by manually (echoing 0 and 1 to the >>>>>>>>>>> GPIOS) >>>>>>>>>>> writing to it in the sys/class/gpio directory by first exporting >>>>>>>>>>> the Gpios and configuring their directions and value.It works >>>>>>>>>>> perfectly >>>>>>>>>>> fine. >>>>>>>>>>> But, >>>>>>>>>>> When I try to do the same using a user space C application I >>>>>>>>>>> dont get the expected response.I am running this app as sudo'er and >>>>>>>>>>> I have >>>>>>>>>>> oscilloscope'd the timings of HIGH/LOW levels of the GPIOs and >>>>>>>>>>> compared it >>>>>>>>>>> with that of the manually writing procedure of GPIOS. The waveform >>>>>>>>>>> and the >>>>>>>>>>> timing diagrams almost matches (95%) >>>>>>>>>>> So, >>>>>>>>>>> What could mysteriously be missing here.?I can go deep into >>>>>>>>>>> analyzing the wave-forms and timing diagrams as well if there is an >>>>>>>>>>> issue >>>>>>>>>>> in the timings of the Signals. >>>>>>>>>>> Please advice.Thanks in advance ! >>>>>>>>>>> -Rp >>>>>>>>>>> >>>>>>>>>>> -- >>>>>>>>>>> For more options, visit http://beagleboard.org/discuss >>>>>>>>>>> --- >>>>>>>>>>> You received this message because you are subscribed to the >>>>>>>>>>> Google Groups "BeagleBoard" group. >>>>>>>>>>> To unsubscribe from this group and stop receiving emails from >>>>>>>>>>> it, send an email to beagleboard...@googlegroups.com. >>>>>>>>>>> To view this discussion on the web visit >>>>>>>>>>> https://groups.google.com/d/msgid/beagleboard/cb65b710-203e-4579-8c08-e2b817dc7a03%40googlegroups.com >>>>>>>>>>> <https://groups.google.com/d/msgid/beagleboard/cb65b710-203e-4579-8c08-e2b817dc7a03%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>>>>>>>> . >>>>>>>>>>> For more options, visit https://groups.google.com/d/optout. >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> -- >>>>>>>>> For more options, visit http://beagleboard.org/discuss >>>>>>>>> --- >>>>>>>>> You received this message because you are subscribed to the Google >>>>>>>>> Groups "BeagleBoard" group. >>>>>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>>>>> send an email to beagleboard...@googlegroups.com. >>>>>>>>> To view this discussion on the web visit >>>>>>>>> https://groups.google.com/d/msgid/beagleboard/521956ed-983d-49b9-85f2-62e269dcf7fa%40googlegroups.com >>>>>>>>> <https://groups.google.com/d/msgid/beagleboard/521956ed-983d-49b9-85f2-62e269dcf7fa%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>>>>>> . >>>>>>>>> >>>>>>>>> For more options, visit https://groups.google.com/d/optout. >>>>>>>>> >>>>>>>> >>>>>>>> >>>>>>> -- >>>>>> For more options, visit http://beagleboard.org/discuss >>>>>> --- >>>>>> You received this message because you are subscribed to the Google >>>>>> Groups "BeagleBoard" group. >>>>>> To unsubscribe from this group and stop receiving emails from it, >>>>>> send an email to beagleboard...@googlegroups.com. >>>>>> To view this discussion on the web visit >>>>>> https://groups.google.com/d/msgid/beagleboard/68d794b1-fdd4-49de-acd0-30923269f437%40googlegroups.com >>>>>> <https://groups.google.com/d/msgid/beagleboard/68d794b1-fdd4-49de-acd0-30923269f437%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>>> . >>>>>> >>>>>> For more options, visit https://groups.google.com/d/optout. >>>>>> >>>>> >>>>> >>>> >>> >> -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to beagleboard+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/beagleboard/ee7f6c47-f840-4a31-8c62-62881313acdc%40googlegroups.com > <https://groups.google.com/d/msgid/beagleboard/ee7f6c47-f840-4a31-8c62-62881313acdc%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to beagleboard+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/beagleboard/CALHSORodQgpVPZ0%3D_qhWt-UHrWg9dBZmM1fjF7X7EdULuE7jsA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
