OMAPL138 GPIO interrupt problem

he he1

Intellectual 260 points

I want to set GP1[1] as a interrupt mode, When a trigger comes,it comes to execute a function,like:

void __irq fun(void)

{

printf("A interrupt comes.\n");

}

How to do it? Should I modify board-da850.c,gpio.c,da850.c files?

Whether I need use request_irq function to request a interrupt or not?

Regards

over 13 years ago

0 he he1 over 13 years ago

Intellectual 260 points

I use sysfs interface like below,but it doesn't work, Can someone help?

int main(int argc, char *argv[])
{
int fd;
if((fd = open("/sys/class/gpio/export", O_WRONLY))<0){
printf("open1 error.\n");
exit(1);
}
write(fd, "17", 3); // Include null!
close(fd);

if((fd = open("/sys/class/gpio/gpio17/direction", O_WRONLY))<0){
printf("open2 error.\n");
exit(1);
}
write(fd, "in", 4); //设置为输入
close(fd);

if((fd=open("/sys/class/gpio/gpio17/edge",O_WRONLY))<0){
printf("open3 error.\n");
exit(1);
}
write(fd,"falling",4); //设置为下降沿

struct pollfd fds;
if((fds.fd=open("/sys/class/gpio/gpio17/value",O_RDONLY))<0){
printf("open value error.\n");
exit(1);
}

fds.events=POLLPRI | POLLERR;
while(fds.events){
printf("hello...\n");
if(poll(&fds,1,-1)<=0){
printf("poll error.\n");
return 1;
}
printf("there comes a tragger.\n");
close(fd);
}
return(0);
}

0 Norman Wong over 13 years ago in reply to he he1

Guru 26430 points

Some of your string writes have count numbers that don't match the string length. You should use strlen() to calculate this for you at runtime or sizeof() at compile time. You might need a dummy read to initiailze the driver. Seems TI drivers need this. Never needed to do this on Atmel platforms. Example code:

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/poll.h>

int writestring(const char *name, const char *string)
{
int fd;

if((fd = open(name, O_WRONLY))<0){
    printf("open %s error.\n", name);
    return(-1);
}
write(fd, string, strlen(string)+1); // Include null!
close(fd);
return(0);
}

int main(int argc, char *argv[])
{
int           fd;
struct pollfd fds;
char          value[2];

if(writestring("/sys/class/gpio/export",           "17"))      return(1);
if(writestring("/sys/class/gpio/gpio17/direction", "in"))      return(1);
if(writestring("/sys/class/gpio/gpio17/edge",      "falling")) return(1);

if((fd=open("/sys/class/gpio/gpio17/value",O_RDONLY))<0){
    printf("open value error.\n");
    return(1);
}

read(fd, value, 2);     /* Dummy read to clear IRQ on TI platforms. */
lseek(fd, 0, SEEK_SET); /* Rewind to beginning to read again. */

fds.fd      = fd;
fds.events = POLLPRI;
fds.revents = 0;

printf("Waiting for events %x\n", fds.events);
if(poll(&fds,1,-1)<=0){
    printf("poll error.\n");
}

printf("Got events %x.\n", fds.revents);

read(fd, value, 2); /* Read the value */
printf("Value is %s.\n", value);

close(fd);

return(0);
}

I did not compile the above code. There may be syntax errors. Some GPIO drivers will report a POLLERR event even if everything seems to be working. Try it with and without.

0 he he1 over 13 years ago in reply to Norman Wong

Intellectual 260 points

Hi Norman

Thank you for your help.

I added below two lines,it works very well now.

read(fd, value, 2); /* Dummy read to clear IRQ on TI platforms. */
lseek(fd, 0, SEEK_SET); /* Rewind to beginning to read again. */

But I don't know what's it mean: read(fd, value, 2); /* Dummy read to clear IRQ on TI platforms. */

Why the read function can clear IRQ?

Regards

0 Norman Wong over 13 years ago in reply to he he1

Guru 26430 points

I haven't looked deep into the GPIO implementation. I believe the first dummy read initiializes the edge detect. I am guessing the code needs the initial state of the GPIO before it can determine a transition has occured. All guesses.

I am not sure if you need to read() after every poll() to "reset" the detect. Does your code work with just poll() in a loop? Never checked myself as my code always needed the value.

0 he he1 over 13 years ago in reply to Norman Wong

Intellectual 260 points

Hi Norman

I used the Gpio-int-test.c examples . The links is: https://www.ridgerun.com/developer/wiki/index.php/Gpio-int-test.c

When I execue the program: ./gpio-int-test 17

It occurs a interrupt once I execue the program.

int main(int argc, char **argv, char **envp)
{
	struct pollfd fdset[2];
	int nfds = 2;
	int gpio_fd, timeout, rc;
	char *buf[MAX_BUF];
	unsigned int gpio;
	int len;



	if (argc < 2) {
		printf("Usage: gpio-int <gpio-pin>\n\n");
		printf("Waits for a change in the GPIO pin voltage level or input on stdin\n");
		exit(-1);
	}

	gpio = atoi(argv[1]);

	gpio_export(gpio);
	gpio_set_dir(gpio, 0);
	gpio_set_edge(gpio, "rising");
	gpio_fd = gpio_fd_open(gpio);
 read(gpio_fd,value,2); //Dummy read to clear IRQ on TI platforms    // I added 
 lseek(gpio_fd,0,SEEK_SET); //Rewind to beginning to read again. // I added 
	timeout = POLL_TIMEOUT;
 
	while (1) {
		memset((void*)fdset, 0, sizeof(fdset));

		fdset[0].fd = STDIN_FILENO;
		fdset[0].events = POLLIN;
      
		fdset[1].fd = gpio_fd;
		fdset[1].events = POLLPRI;

		rc = poll(fdset, nfds, timeout);

.............................................

When I added the two red lines,it won't occur a interrupt.

I don't know why.

Thank you very much!

Regards

Processors

Processors forum

OMAPL138 GPIO interrupt problem