DocID026411 Rev 2

17/26

AN4503

Linux kernel space

26

struct input_event {

struct timeval time;

uint16_t type;

uint16_t code;

int32_t value;

};

int main(int argc, char *argv[])

{

int fd;

struct input_event ev;

assert(16 == sizeof(struct input_event));

if (argc != 2) {

fprintf(stderr, "missing /dev/input/XXX\n");

return 1;

}

if ((fd = open(argv[1], O_RDONLY)) == -1) {

perror("open");

return 1;

}

while (1) {

do

{

read(fd, &ev, sizeof(struct input_event));

if (ev.type == EV_ABS)

printf("type:%u code:%u value:%d\n", ev.type, ev.code, ev.value);

usleep(500000);

/* 2 reads per sec */

} while (ev.type != EV_SYN);

}

close(fd);

return 0;

}

Type, time, code and value correspond to the numbers that fill the shell when the getevent

command is launched.

In our example, it can be seen that the types for the pressure (abs_pr), temperature (chosen

as abs_gas) and humidity (chosen as abs_misc) are respectively: 18, 09 and 28.