>
> *The GPIO is high for about 1.5 Milliseconds. The usleep()-function is not
> linear, so it did not work with any other value e.g. usleep(500). Sometimes
> I decrease the value by one (1 microsecond) but the time decrease by 100
> microseconds.*
> *Has anybody an idea what could be wrong? *
>
First of all, usleep() is not your problem. The problem most likely is
related to kernel latency. You could improve this by using a PREEMPT RT
kernel, but that will only at best give you 95% determinism.
Second, since you have not made your code public, we can not tell if
servo.setValue() is well written or not. In the context of determinism. I
will say however if you're not using mmap() with /dev/mem/ on the GPIO
registers directly. Your code will be "slow", and not very deterministic.
Lastly, if you need absolute determinism, you had better start using the
PRUs . . .
On Thu, Dec 3, 2015 at 4:30 AM, <andreas.bu...@hs-owl.de> wrote:
> Hi,
>
> I am trying to control a servo with my BeagleBoneBlack using Angstrom. I
> must have a high-level on a GPIO for 1 millisecond. I use the following
> simple code:
>
> while(1){
> servo.setValue(BlackLib::low);
> usleep(19000);
> servo.setValue(BlackLib::high);
> usleep(1000);
> }
>
> The GPIO is high for about 1.5 Milliseconds. The usleep()-function is not
> linear, so it did not work with any other value e.g. usleep(500). Sometimes
> I decrease the value by one (1 microsecond) but the time decrease by 100
> microseconds.
> Has anybody an idea what could be wrong?
>
> --
> For more options, visit http://beagleboard.org/discuss
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