I read gpio.txt in Documentation of kernel and try to use it.
I use:
# echo 13 > /sys/class/gpio/export
# echo in > /root/tasto1/direction
# cat /root/tasto1/direction
in
# cat /root/tasto1/value
1
when the button is pressed:
# cat /root/tasto1/value
0
# cat /root/tasto1/edge
none
# echo both > /root/tasto1/edge
# cat /sys/kernel/debug/gpio
[...]
B5 gpio-13 (sysfs ) in hi irq-77 edge-both
[...]
# cat /proc/irq/77/spurious p
count 15
unhandled 0
last_unhandled 0 ms
cat: p: No such file or directory
Ture:~# cat /proc/irq/77/spurious
count 15
unhandled 0
last_unhandled 0 ms
I try the follow code in a while (1):
// /root/tasto1 is a symbolic link to /sys/class/gpio/gpio13/
pfd.fd = open("/root/tasto1/value", O_RDONLY);
pfd.events = POLLPRI | POLLERR;
//ready = poll(&pfd, 1, -1);
ready = poll(&pfd, 1, 100000);
lseek (pfd.fd, 0, SEEK_SET);
val = read(pfd.fd, buf, 254);
//the output are: 1, 10, 10
printf ("%d, %d, %d\n", ready, pfd.revents, pfd.events);
printf ("%d, %s\n", val, buf );
close(pfd.fd);
But it don't wait for an edge but they exit immediatly.
Why? where is the problem?
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