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i2c驱动之调用ioctl函数进行读写at24c08

//作者:王磊

//日期:2013.11.17

//文件功能:实现ioctl函数调用，并操作i2c设备/dev/i2c/0进行读写数据

#include<stdio.h>

#include<linux/types.h>

#include<fcntl.h>

#include<unistd.h>

#include<stdlib.h>

#include<sys/types.h>

#include<sys/ioctl.h>

#include<errno.h>

#include<assert.h>

#include<string.h>

#include<linux/i2c.h>

#include<linux/i2c-dev.h>

int main(int argc, char** argv)

{

struct i2c_rdwr_ioctl_data work_queue;

unsigned int slave_address,reg_address,dat;

int i,ret;

unsigned char val;

unsigned int fd;

if(argc != 3)

{

printf("usage:./eeprom_ioctl address data\n");

return 0;

}

fd=open("/dev/i2c/0",O_RDWR);

if(!fd)

{

printf("error on opening the device file\n");

exit(1);

}

ioctl(fd,I2C_TIMEOUT,2);//超时时间

ioctl(fd,I2C_RETRIES,1);//重复次数

slave_address = 0x50;//24c08的访问地址是101000b

reg_address = (argv[1][2]-48)<<4 | (argv[1][3]-48);

dat = (argv[2][2]-48)<<4 | (argv[2][3]-48);

//nmsgs决定了有多少start信号

//一个msgs对应一个start信号

//在nmsg个信号结束后总线会产生一个stop

//下面因为在操作时序中最多用到2个start信号(字节读操作中)

work_queue.nmsgs = 2;

work_queue.msgs = (struct i2c_msg *)malloc(work_queue.nmsgs * sizeof(work_queue.msgs));

if(!work_queue.msgs)

{

printf("memory alloc failed");

close(fd);

exit(1);

}

//往i2c里面写数据

printf("began to write:\n");

work_queue.nmsgs = 1;

(work_queue.msgs[0]).len = 2;//buf的长度

(work_queue.msgs[0]).flags = 0;//write

(work_queue.msgs[0]).addr = slave_address;//设备地址

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

(work_queue.msgs[0]).buf[0] = reg_address;//写的地址

(work_queue.msgs[0]).buf[1] = dat;//你要写的数据

ret = ioctl(fd, I2C_RDWR, (unsigned long)&work_queue);

if(ret < 0)

printf("error during I2C_RDWR ioctl with error code %d\n", ret);

//从i2c里面读出数据

printf("\nbegan to read:\n");

work_queue.nmsgs = 2;

//先设定一下地址

(work_queue.msgs[0]).len = 1;

(work_queue.msgs[0]).flags = 0;//write

(work_queue.msgs[0]).addr = slave_address;

(work_queue.msgs[0]).buf[0] = reg_address;//因为上面buf已经分配过了

//然后从刚才设定的地址处读

(work_queue.msgs[1]).len = 1;

(work_queue.msgs[1]).flags = I2C_M_RD;

(work_queue.msgs[1]).addr = slave_address;

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

(work_queue.msgs[1]).buf[0] = 0;//初始化读缓冲

ret = ioctl(fd, I2C_RDWR, (unsigned long)&work_queue);

if(ret < 0)

printf("error during I2C_RDWR ioctl with error code %d\n", ret);

close(fd);

return 0;

}

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作者：luckywang1103

来源：CSDN

原文：https://blog.csdn.net/luckywang1103/article/details/16810833