Re: [beagleboard] Re: Counting events
Thanks a lot Hussam!
I could not get it working using the /sys/class/gpio/gpioxx/edge. Maybe
/sys/class/gpioxx/value would work? But by modifying the sample device tree
overlay from www.hipstercircuits.com and /dev/input/event1. I was able to
get it going using the following code.
#include stdio.h
#include stddef.h
#include time.h
#include iostream
#include fcntl.h
#include unistd.h
#include sys/types.h
#include string.h
#include termios.h
#include signal.h
#include stdlib.h
using namespace std;
volatile int counter = 0;
void IRQHandler(int sig){
counter ++;
cout counter;
}
int main(void){
struct sigaction saio;
int fd1;
fd1 = open(/dev/input/event1, O_RDWR|O_NONBLOCK);
saio.sa_handler = IRQHandler;
//saio.sa_mask = 0;
saio.sa_flags = 0;
saio.sa_restorer = NULL;
sigaction(SIGIO,saio,NULL);
fcntl(fd1, F_SETOWN, getpid());
fcntl(fd1, F_SETFL, FASYNC);
while(1){
}
}
On Sun, Feb 23, 2014 at 8:57 PM, Hussam Hertani halhe...@gmail.com wrote:
Dorian, here's a little example. First open the file and get a file
descriptor, then use FCNTL with SETOWN command to send SIGIO to current
process. Use fcntl to set the FASYNC flag then populate the signal
structure. This code was not tested but hopefully should give you an idea
as to what to do...
int counter = 0;
int main(){
struct sigaction saio;
int fd ;
fd = open(/sys/class/blahblah/edge,O_RDWR | O_NONBLOCK); // open file
descriptor for the edge
/* install the signal handler before making the device asynchronous */
saio.sa_handler = signal_handler_IO;
saio.sa_mask = 0;
saio.sa_flags = 0;
saio.sa_restorer = NULL;
sigaction(SIGIO,saio,NULL);
/* allow the process to receive SIGIO */
fcntl(fd, F_SETOWN, getpid());
/* Make the file descriptor asynchronous (the manual page says only
O_APPEND and O_NONBLOCK, will work with F_SETFL...) */
fcntl(fd, F_SETFL, FASYNC);
}
void signal_handler_IO (int status)
{
counter++;
}
Linux purists generally don't like using signals,,,too many can cause
many conflicts/race conditions that are hard to debug.
http://ajaxxx.livejournal.com/62378.html
most of the above code was taken from this link that has code for SIGIO
asynchronous serial port access:
http://www.tldp.org/HOWTO/pdf/Serial-Programming-HOWTO.pdf
For more on signals in general
http://beej.us/guide/bgipc/
http://ph7spot.com/musings/introduction-to-unix-signals-and-system-calls
http://www.linuxprogrammingblog.com/all-about-linux-signals?page=1
For more on fcntl:
http://linux.die.net/man/2/fcntl
There's also real-time signals. I haven't heard of those before today.
But they seem to have less race conditions issues. I'll have to read up on
them. Unfortunately My Linux Signal Programming fu is very limited. I
recommend that you get yourself a good text reference on Linux System
Programming as well. It will help.
Regards,
Hussam
On Sun, Feb 23, 2014 at 7:35 PM, Dorian Levy dorianal...@gmail.comwrote:
Something like SIGIO is what I was trying to do. I was
trying signal(SIGINT, IRQHandler), but something is not
right. How do I attach it, and why do Linux enthusiasts not recommend this?
On Sun, Feb 23, 2014 at 1:40 PM, halhe...@gmail.com wrote:
Dorian,
I haven't tried any of these myself but I see no reason why they
shouldn't work.
- you could use a fork to create a child process. In this child
process use the poll()/select() calls to detect a change in the edge
file.
When this happens a variable could be incremented and piped back to the
parent process.
- You could use threads...i.e. a thread calls poll()/select() to
detect a change in the edge file and then updates a counts
variables.with threads all threads share the variables so this will
be
easier. but could be more convoluted.
- You could try monitoring the edge file with GDK/GTK libs
monitoring I/O calls
https://developer.gnome.org/gtk-tutorial/2.90/x1770.html. Qt has a
QIODevice class that does the same thing.
- You could also attach the SIGIO signal to the file descriptor for
the edge file and write a signal handler that increments a
variable...though Linux purists do not recommend this
Hussam
On Saturday, February 22, 2014 1:41:02 PM UTC-5, Dorian Levy wrote:
I want to use a hall effect motor encoder to determine the number of
revolutions of a wheel. Using the BB-KEYS I am able to set
up /dev/inputs/event1 that captures the event and records the number of
interrupts in /proc/interrupts. I believe setting
/sys/class/gpio/gpioxx/edge will do pretty much the same. I haven't been
able to figure out how to count them in a C/C++ code. Is it bes to set up
an interrupt and count or try to read the /proc/interrupt file? Polling is
not an option because there are two wheel that need to be counted. I would
prefer to have and ISR that counts each time it is triggered, but I have
not been able to figure out how to set it up. Any
[beagleboard] Re: Counting events
I need to do something similar counting pulses generated by a hall effect sensor in a flow meter. Haven't started looking at it yet, if you solve this please post back to the thread. On Saturday, February 22, 2014 12:41:02 PM UTC-6, Dorian Levy wrote: I want to use a hall effect motor encoder to determine the number of revolutions of a wheel. Using the BB-KEYS I am able to set up /dev/inputs/event1 that captures the event and records the number of interrupts in /proc/interrupts. I believe setting /sys/class/gpio/gpioxx/edge will do pretty much the same. I haven't been able to figure out how to count them in a C/C++ code. Is it bes to set up an interrupt and count or try to read the /proc/interrupt file? Polling is not an option because there are two wheel that need to be counted. I would prefer to have and ISR that counts each time it is triggered, but I have not been able to figure out how to set it up. Any help would be greatly appreciated since I have spent the last few days trying to research this without much luck. Thanks, Dorian -- 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. For more options, visit https://groups.google.com/groups/opt_out.
Re: [beagleboard] Re: Counting events
Something like SIGIO is what I was trying to do. I was trying signal(SIGINT, IRQHandler), but something is not right. How do I attach it, and why do Linux enthusiasts not recommend this? On Sun, Feb 23, 2014 at 1:40 PM, halhe...@gmail.com wrote: Dorian, I haven't tried any of these myself but I see no reason why they shouldn't work. - you could use a fork to create a child process. In this child process use the poll()/select() calls to detect a change in the edge file. When this happens a variable could be incremented and piped back to the parent process. - You could use threads...i.e. a thread calls poll()/select() to detect a change in the edge file and then updates a counts variables.with threads all threads share the variables so this will be easier. but could be more convoluted. - You could try monitoring the edge file with GDK/GTK libs monitoring I/O calls https://developer.gnome.org/gtk-tutorial/2.90/x1770.html. Qt has a QIODevice class that does the same thing. - You could also attach the SIGIO signal to the file descriptor for the edge file and write a signal handler that increments a variable...though Linux purists do not recommend this Hussam On Saturday, February 22, 2014 1:41:02 PM UTC-5, Dorian Levy wrote: I want to use a hall effect motor encoder to determine the number of revolutions of a wheel. Using the BB-KEYS I am able to set up /dev/inputs/event1 that captures the event and records the number of interrupts in /proc/interrupts. I believe setting /sys/class/gpio/gpioxx/edge will do pretty much the same. I haven't been able to figure out how to count them in a C/C++ code. Is it bes to set up an interrupt and count or try to read the /proc/interrupt file? Polling is not an option because there are two wheel that need to be counted. I would prefer to have and ISR that counts each time it is triggered, but I have not been able to figure out how to set it up. Any help would be greatly appreciated since I have spent the last few days trying to research this without much luck. Thanks, Dorian -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to a topic in the Google Groups BeagleBoard group. To unsubscribe from this topic, visit https://groups.google.com/d/topic/beagleboard/RhSCj3GgAj8/unsubscribe. To unsubscribe from this group and all its topics, send an email to beagleboard+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out. -- 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. For more options, visit https://groups.google.com/groups/opt_out.
Re: [beagleboard] Re: Counting events
Dorian, here's a little example. First open the file and get a file
descriptor, then use FCNTL with SETOWN command to send SIGIO to current
process. Use fcntl to set the FASYNC flag then populate the signal
structure. This code was not tested but hopefully should give you an idea
as to what to do...
int counter = 0;
int main(){
struct sigaction saio;
int fd ;
fd = open(/sys/class/blahblah/edge,O_RDWR | O_NONBLOCK); // open file
descriptor for the edge
/* install the signal handler before making the device asynchronous */
saio.sa_handler = signal_handler_IO;
saio.sa_mask = 0;
saio.sa_flags = 0;
saio.sa_restorer = NULL;
sigaction(SIGIO,saio,NULL);
/* allow the process to receive SIGIO */
fcntl(fd, F_SETOWN, getpid());
/* Make the file descriptor asynchronous (the manual page says only
O_APPEND and O_NONBLOCK, will work with F_SETFL...) */
fcntl(fd, F_SETFL, FASYNC);
}
void signal_handler_IO (int status)
{
counter++;
}
Linux purists generally don't like using signals,,,too many can cause many
conflicts/race conditions that are hard to debug.
http://ajaxxx.livejournal.com/62378.html
most of the above code was taken from this link that has code for SIGIO
asynchronous serial port access:
http://www.tldp.org/HOWTO/pdf/Serial-Programming-HOWTO.pdf
For more on signals in general
http://beej.us/guide/bgipc/
http://ph7spot.com/musings/introduction-to-unix-signals-and-system-calls
http://www.linuxprogrammingblog.com/all-about-linux-signals?page=1
For more on fcntl:
http://linux.die.net/man/2/fcntl
There's also real-time signals. I haven't heard of those before today. But
they seem to have less race conditions issues. I'll have to read up on
them. Unfortunately My Linux Signal Programming fu is very limited. I
recommend that you get yourself a good text reference on Linux System
Programming as well. It will help.
Regards,
Hussam
On Sun, Feb 23, 2014 at 7:35 PM, Dorian Levy dorianal...@gmail.com wrote:
Something like SIGIO is what I was trying to do. I was
trying signal(SIGINT, IRQHandler), but something is not
right. How do I attach it, and why do Linux enthusiasts not recommend this?
On Sun, Feb 23, 2014 at 1:40 PM, halhe...@gmail.com wrote:
Dorian,
I haven't tried any of these myself but I see no reason why they
shouldn't work.
- you could use a fork to create a child process. In this child
process use the poll()/select() calls to detect a change in the edge file.
When this happens a variable could be incremented and piped back to the
parent process.
- You could use threads...i.e. a thread calls poll()/select() to
detect a change in the edge file and then updates a counts
variables.with threads all threads share the variables so this will be
easier. but could be more convoluted.
- You could try monitoring the edge file with GDK/GTK libs monitoring
I/O calls https://developer.gnome.org/gtk-tutorial/2.90/x1770.html.
Qt has a QIODevice class that does the same thing.
- You could also attach the SIGIO signal to the file descriptor for
the edge file and write a signal handler that increments a
variable...though Linux purists do not recommend this
Hussam
On Saturday, February 22, 2014 1:41:02 PM UTC-5, Dorian Levy wrote:
I want to use a hall effect motor encoder to determine the number of
revolutions of a wheel. Using the BB-KEYS I am able to set
up /dev/inputs/event1 that captures the event and records the number of
interrupts in /proc/interrupts. I believe setting
/sys/class/gpio/gpioxx/edge will do pretty much the same. I haven't been
able to figure out how to count them in a C/C++ code. Is it bes to set up
an interrupt and count or try to read the /proc/interrupt file? Polling is
not an option because there are two wheel that need to be counted. I would
prefer to have and ISR that counts each time it is triggered, but I have
not been able to figure out how to set it up. Any help would be greatly
appreciated since I have spent the last few days trying to research this
without much luck.
Thanks,
Dorian
--
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