Linux下I2C应用程序

#include

#include

#include

#include

#include

#define I2C_RDWR 0x0707

struct i2c_rdwr_ioctl_data {

struct i2c_msg  *msgs; /* pointers to i2c_msgs */

unsigned int nmsgs; /* number of i2c_msgs */

};

struct i2c_msg {

unsigned short addr; /* slave address */

unsigned short flags;

unsigned short len; /* msg length */

unsigned char *buf; /* pointer to msg data */

};

int main()

{

int fd;

//1.打开通用设备文件

fd = open("/dev/hi_i2c",O_RDWR);

struct i2c_rdwr_ioctl_data data;

data.msgs = (struct i2c_msg *)malloc(2*sizeof(struct i2c_msg));

//2.构造写入到从设备的消息

data.nmsgs = 1;   //消息的数目

data.msgs[0].len = 2;

data.msgs[0].addr = 0x20;

data.msgs[0].flags = 0;  //flags说明读还是写

data.msgs[0].buf = (unsigned char *)malloc(2);

data.msgs[0].buf[0] = 0x01;     //填入从设备寄存器地址

data.msgs[0].buf[1] = 0x20;     //向寄存器写入的值

//3.使用ioctl写入数据

ioctl(fd,I2C_RDWR,(unsigned long)&data);

//4.构造读出从设备数据的消息

data.nmsgs = 2;

data.msgs[0].len = 1;

data.msgs[0].addr = 0x20; //从设备地址

data.msgs[0].flags = 0;  //flags说明读还是写

//data.msgs[0].buf = (unsigned char *)malloc(2);

data.msgs[0].buf[0] = 0x01;     //填入从设备寄存器地址 

data.msgs[1].len = 1;

data.msgs[1].addr = 0x20; //从设备地址

data.msgs[1].flags = 1;  //flags说明读还是写

data.msgs[1].buf = (unsigned char *)malloc(2);

data.msgs[1].buf[0] = 0;     //填入从设备寄存器地址 

//5.使用ioctl读数据

ioctl(fd,I2C_RDWR,(unsigned long)&data);

printf("buf[0]=%x\n",data.msgs[1].buf[0]);

//6.关闭设备

close(fd);

}