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 <yyrk...@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 <yyrk...@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 <raulpbloo...@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
>>>>>>>>
>>>>>>>> --
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>>>>>>>>
>>>>>>>
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>>>>>
>>>>>
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>
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