Gsensor

Gsensor node

Gsensor node in /dev directory

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$ ll /dev/accel 
crw-rw-rw- 1 root root 10, 50 Mar 18 12:17 /dev/accel

Gsensor demo

The Gsensor example is to read and write nodes through the ioctl function

source code

The source code only realizes the use of default settings to read data, other functions users can implement by yourself

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#include <stdio.h>
#include <sys/ioctl.h>
#include <fcntl.h>

#define GBUFF_SIZE                12
#define GSENSOR_IOCTL_MAGIC       'a'

#define GSENSOR_IOCTL_INIT              _IO(GSENSOR_IOCTL_MAGIC, 0x01)
#define GSENSOR_IOCTL_RESET             _IO(GSENSOR_IOCTL_MAGIC, 0x04)
#define GSENSOR_IOCTL_CLOSE             _IO(GSENSOR_IOCTL_MAGIC, 0x02)
#define GSENSOR_IOCTL_START             _IO(GSENSOR_IOCTL_MAGIC, 0x03)
#define GSENSOR_IOCTL_GETDATA           _IOR(GSENSOR_IOCTL_MAGIC, 0x08, char[GBUFF_SIZE+1])
#define GSENSOR_IOCTL_APP_SET_RATE      _IOW(GSENSOR_IOCTL_MAGIC, 0x10, short)
#define GSENSOR_IOCTL_GET_CALIBRATION   _IOR(GSENSOR_IOCTL_MAGIC, 0x11, int[3])


struct sensor_axis {
    int x;
    int y;
    int z;
};

char *gsensor_device = "/dev/accel";
int gsensor_fd = -1;

int main(int argc, char **argv){

        struct sensor_axis gsensor_data;

        gsensor_fd = open(gsensor_device, O_RDWR);

        if (0 > gsensor_fd){
                printf("gsensor node open failed ...\n");
                exit(-1);
        }else{
                printf("gsensor node open success!!!\n");
        }

        if(ioctl(gsensor_fd, GSENSOR_IOCTL_START, NULL) == -1) {
                printf("gsensor start failed ... \n");
                close(gsensor_fd);
                exit(-1);
        }else{
                printf("gsensor start sueecss !!!\n");
        }

        printf("start to get gsensor data ...\n");
        while(1){

                if(ioctl(gsensor_fd, GSENSOR_IOCTL_GETDATA, &gsensor_data) == -1) {
                        printf("gsensor get data faile ... \n");
                        close(gsensor_fd);
                        exit(-1);
                }

                printf("gsensor_data -- x:%d,y:%d,z:%d \n", gsensor_data.x, gsensor_data.y, gsensor_data.z);
                sleep(1);
        }
        close(gsensor_fd);

		return 0;
}

compile

Use gcc to compile directly on the board

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$ gcc -o gsensor_sample_demo gsensor_sample_demo.c
gsensor_sample_demo.c: In function ‘main’:
gsensor_sample_demo.c:34:3: warning: implicit declaration of function ‘exit’ [-Wimplicit-function-declaration]
   34 |   exit(-1);
      |   ^~~~
gsensor_sample_demo.c:34:3: warning: incompatible implicit declaration of built-in function ‘exit’
gsensor_sample_demo.c:4:1: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’
    3 | #include <fcntl.h>
  +++ |+#include <stdlib.h>
    4 |
gsensor_sample_demo.c:41:3: warning: implicit declaration of function ‘close’; did you mean ‘pclose’? [-Wimplicit-function-declaration]
   41 |   close(gsensor_fd);
      |   ^~~~~
      |   pclose
gsensor_sample_demo.c:42:3: warning: incompatible implicit declaration of built-in function ‘exit’
   42 |   exit(-1);
      |   ^~~~
gsensor_sample_demo.c:42:3: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’
gsensor_sample_demo.c:53:4: warning: incompatible implicit declaration of built-in function ‘exit’
   53 |    exit(-1);
      |    ^~~~
gsensor_sample_demo.c:53:4: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’
gsensor_sample_demo.c:57:3: warning: implicit declaration of function ‘sleep’ [-Wimplicit-function-declaration]
   57 |   sleep(1);
      |   ^~~~~

Run

Rotate the board while running, you can see the changes in gsensor data

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$ ./gsensor_sample_demo
gsensor node open success!!!
gsensor start sueecss !!!
start to get gsensor data ...
gsensor_data -- x:-2112,y:16,z:16448
gsensor_data -- x:-2128,y:176,z:16128
gsensor_data -- x:-1632,y:2784,z:15968
gsensor_data -- x:7440,y:-3760,z:14608
gsensor_data -- x:-512,y:-7280,z:12128
gsensor_data -- x:-14384,y:-2336,z:11280
gsensor_data -- x:9952,y:-5264,z:15216
gsensor_data -- x:-6432,y:3760,z:24896