GPIO interrupt reading timeout

GPIO interrupt reading timeout

[Gabriel Dinse]

Hello,

I currently have a loop rt_task for reading interrupts on a GPIO pin of 
my raspberry pi.

I'm using:
ret = read(pin, &value, sizeof(value));

but I don't want it to block forever, because my task should exit when 
there are not more interrupts to read. Can I use "select" for 
introducing a reading timeout on my loop and yet being "real-time"?

Thank you,
Gabriel Dinse

Re: GPIO interrupt reading timeout

[Greg Gallagher]

On Sun, Feb 28, 2021 at 7:18 AM Gabriel Dinse via Xenomai <
xenomai@xenomai.org> wrote:

> Hello,
>
> I currently have a loop rt_task for reading interrupts on a GPIO pin of
> my raspberry pi.
>
> I'm using:
> ret = read(pin, &value, sizeof(value));
>
> but I don't want it to block forever, because my task should exit when
> there are not more interrupts to read. Can I use "select" for
> introducing a reading timeout on my loop and yet being "real-time"?
>
> Thank you,
> Gabriel Dinse


>
If you are using the posix skin ( which I believe you are) then yes, using
select will translate into using the RT version of select, and you can use
a timeout.

Thanks

Greg

>
>

Re: GPIO interrupt reading timeout

[Gabriel Dinse]

On Sun, Feb 28, 2021 at 8:08 am, Greg Gallagher <greg@embeddedgreg.com> 
wrote:
> 
> 
> On Sun, Feb 28, 2021 at 7:18 AM Gabriel Dinse via Xenomai 
> <xenomai@xenomai.org <mailto:xenomai@xenomai.org>> wrote:
>> Hello,
>> 
>>  I currently have a loop rt_task for reading interrupts on a GPIO 
>> pin of
>>  my raspberry pi.
>> 
>>  I'm using:
>>  ret = read(pin, &value, sizeof(value));
>> 
>>  but I don't want it to block forever, because my task should exit 
>> when
>>  there are not more interrupts to read. Can I use "select" for
>>  introducing a reading timeout on my loop and yet being "real-time"?
>> 
>>  Thank you,
>>  Gabriel Dinse
>> 
> 
> If you are using the posix skin ( which I believe you are) then yes, 
> using select will translate into using the RT version of select, and 
> you can use a timeout.
> 
> Thanks
> 
> Greg
>> 

Should I specify posix on compilation? I'm using alchemy as well right 
now. my Makefile is like this:

   0 STAGE=../../output/target/
   1 XENO_CONFIG := ../../output/target/usr/xenomai/bin/xeno-config
   2 CFLAGS := $(shell DESTDIR=$(STAGE) $(XENO_CONFIG) --rtdm 
--skin=alchemy --      cflags)
   3 LDFLAGS := $(shell DESTDIR=$(STAGE) $(XENO_CONFIG) --rtdm 
--skin=alchemy --     ldflags)
   4 CC := $(shell DESTDIR=$(STAGE) $(XENO_CONFIG) --cc)
   5
   6 EXECUTABLE := program
   7
   8
   9 all: $(EXECUTABLE)
  10
  11 %: %.c
  12     $(CC) -o $@ $< $(CFLAGS) $(LDFLAGS)