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#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <error.h>
#include <errno.h>
#include <limits.h>
#include <unistd.h>
#include <string.h>
#include "linux/input.h"
#define INPUT_DEV_NODE "/dev/input/by-path/platform-ffc04000.i2c-event"
#define SYSFS_DEVICE_DIR "/sys/devices/platform/soc/ffc04000.i2c/i2c-0/0-0053/"
#define EV_CODE_X (0)
#define EV_CODE_Y (1)
#define EV_CODE_Z (2)
#define LOOP_COUNT (100)
void write_sysfs_cntl_file(const char *dir_name, const char *file_name,
const char *write_str) {
char path[PATH_MAX];
int path_length;
int file_fd;
int result;
// create the path to the file we need to open
path_length = snprintf(path, PATH_MAX, "%s/%s", dir_name, file_name);
if(path_length < 0)
error(1, 0, "path output error");
if(path_length >= PATH_MAX)
error(1, 0, "path length overflow");
// open the file
file_fd = open(path, O_WRONLY | O_SYNC);
if(file_fd < 0)
error(1, errno, "could not open file '%s'", path);
// write the string to the file
result = write(file_fd, write_str, strlen(write_str));
if(result < 0)
error(1, errno, "writing to '%s'", path);
if((size_t)(result) != strlen(write_str))
error(1, errno, "buffer underflow writing '%s'", path);
// close the file
result = close(file_fd);
if(result < 0)
error(1, errno, "could not close file '%s'", path);
}
int main(void) {
int event_dev_fd;
const char *input_dev_node = INPUT_DEV_NODE;
int result;
int i;
int loop;
struct input_event the_event;
struct input_absinfo the_absinfo;
int abs_value_array[3] = {0};
int last_value_x;
int last_value_y;
int last_value_z;
int event_type_array[LOOP_COUNT];
int event_code_array[LOOP_COUNT];
int event_value_array[LOOP_COUNT];
int x_abs_value_array[LOOP_COUNT];
int y_abs_value_array[LOOP_COUNT];
int z_abs_value_array[LOOP_COUNT];
// enable adxl
write_sysfs_cntl_file(SYSFS_DEVICE_DIR, "disable", "0");
// set the sample rate to maximum
write_sysfs_cntl_file(SYSFS_DEVICE_DIR, "rate", "15");
// do not auto sleep
write_sysfs_cntl_file(SYSFS_DEVICE_DIR, "autosleep", "0");
// open the event device node
event_dev_fd = open(input_dev_node, O_RDONLY | O_SYNC);
if(event_dev_fd < 0)
error(1, errno, "could not open file '%s'", input_dev_node);
// read the current state of each axis
printf("\n");
for(i = 0 ; i < 3 ; i++ ) {
result = ioctl (event_dev_fd, EVIOCGABS(i), &the_absinfo);
if(result < 0)
error(1, errno, "ioctl from '%s'", input_dev_node);
switch(i) {
case(EV_CODE_X) :
printf("X-axis\n");
break;
case(EV_CODE_Y) :
printf("Y-axis\n");
break;
case(EV_CODE_Z) :
printf("Z-axis\n");
break;
default :
printf("unknown-axis\n");
break;
}
printf("%14s = %d\n", "value", the_absinfo.value);
printf("%14s = %d\n", "minimum", the_absinfo.minimum);
printf("%14s = %d\n", "maximum", the_absinfo.maximum);
printf("%14s = %d\n", "fuzz", the_absinfo.fuzz);
printf("%14s = %d\n", "flat", the_absinfo.flat);
printf("%14s = %d\n", "resolution", the_absinfo.resolution);
printf("\n");
}
fflush(stdout);
// read the next LOOP_COUNT events
for(loop = 0 ; loop < LOOP_COUNT ; loop++) {
// read the next event
result = read(event_dev_fd, &the_event,
sizeof(struct input_event));
if(result < 0)
error(1, errno, "reading %d from '%s'",
sizeof(struct input_event),
input_dev_node);
if(result != sizeof(struct input_event))
error(1, 0, "did not read %d bytes from '%s'",
sizeof(struct input_event),
input_dev_node);
event_type_array[loop] = the_event.type;
event_code_array[loop] = the_event.code;
event_value_array[loop] = the_event.value;
// read the current state of each axis
for(i = 0 ; i < 3 ; i++ ) {
result = ioctl (event_dev_fd, EVIOCGABS(i),
&the_absinfo);
if(result < 0)
error(1, errno, "ioctl from '%s'",
input_dev_node);
abs_value_array[i] = the_absinfo.value;
}
x_abs_value_array[loop] = abs_value_array[0];
y_abs_value_array[loop] = abs_value_array[1];
z_abs_value_array[loop] = abs_value_array[2];
}
// print the accumulated event data
printf("Event capture results...\n");
for(loop = 0 ; loop < LOOP_COUNT ; loop++) {
// if the event is EV_ABS, then process it, otherwise ignore it
if(event_type_array[loop] == EV_SYN) {
printf("EV_SYN event\n");
printf("%d,%d,%d\n",
x_abs_value_array[loop],
y_abs_value_array[loop],
z_abs_value_array[loop]);
} else if(event_type_array[loop] == EV_ABS) {
// look for the codes that we expect
switch(event_code_array[loop]) {
case(EV_CODE_X) :
printf("X-axis EV_ABS event = ");
break;
case(EV_CODE_Y) :
printf("Y-axis EV_ABS event = ");
break;
case(EV_CODE_Z) :
printf("Z-axis EV_ABS event = ");
break;
default :
printf("unknown");
break;
}
// output the value of the event
printf("'%d'\n", event_value_array[loop]);
printf("%d,%d,%d\n",
x_abs_value_array[loop],
y_abs_value_array[loop],
z_abs_value_array[loop]);
} else {
printf("Unexpected event type '%d'\n",
event_type_array[loop]);
}
}
fflush(stdout);
// read current value for each axis so we can monitor changes by polling
// x-axis
result = ioctl (event_dev_fd, EVIOCGABS(0),
&the_absinfo);
if(result < 0)
error(1, errno, "ioctl from '%s'",
input_dev_node);
last_value_x = the_absinfo.value;
// y-axis
result = ioctl (event_dev_fd, EVIOCGABS(1),
&the_absinfo);
if(result < 0)
error(1, errno, "ioctl from '%s'",
input_dev_node);
last_value_y = the_absinfo.value;
// z-axis
result = ioctl (event_dev_fd, EVIOCGABS(2),
&the_absinfo);
if(result < 0)
error(1, errno, "ioctl from '%s'",
input_dev_node);
last_value_z = the_absinfo.value;
// capture the next LOOP_COUNT transitions that occur on any axis
for(loop = 0 ; loop < LOOP_COUNT ;) {
// read the current state of each axis
for(i = 0 ; i < 3 ; i++ ) {
result = ioctl (event_dev_fd, EVIOCGABS(i),
&the_absinfo);
if(result < 0)
error(1, errno, "ioctl from '%s'",
input_dev_node);
abs_value_array[i] = the_absinfo.value;
}
// if any axis has changed, log the new values, otherwise skip
if( (abs_value_array[0] != last_value_x) ||
(abs_value_array[1] != last_value_y) ||
(abs_value_array[2] != last_value_z) ) {
x_abs_value_array[loop] = abs_value_array[0];
y_abs_value_array[loop] = abs_value_array[1];
z_abs_value_array[loop] = abs_value_array[2];
last_value_x = abs_value_array[0];
last_value_y = abs_value_array[1];
last_value_z = abs_value_array[2];
loop++;
}
}
// print the polling results
printf("\n");
printf("Polling results\n");
for(loop = 0 ; loop < LOOP_COUNT ; loop++) {
printf("%d,%d,%d\n",
x_abs_value_array[loop],
y_abs_value_array[loop],
z_abs_value_array[loop]);
}
// close the device node
result = close(event_dev_fd);
if(result < 0)
error(1, errno, "could not close file '%s'", input_dev_node);
// disable adxl
write_sysfs_cntl_file(SYSFS_DEVICE_DIR, "disable", "1");
}
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