通过i2c设备节点操作i2c从设备报I/O错误

Crom · 发表于 2016-7-8 15:48:10

请教一个关于i2c设备驱动的问题
我想通过i2c设备节点操作i2c从设备
#include <stdio.h>
#include <linux/types.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <errno.h>
#define I2C_RETRIES 0X0701
#define I2C_TIMEOUT 0X0702
#define I2C_RDWR 0X0707

struct i2c_msg
{
unsigned short addr;
unsigned short flags;
#define I2C_M_TEN 0X0010
#define I2C_M_RD 0X0001
unsigned short len;
unsigned char *buf;
};

struct i2c_rdwr_ioctl_data
{
struct i2c_msg *msgs;
int nmsgs;
};

int main(int argc ,char* argv[])
{
int fd,ret;
struct i2c_rdwr_ioctl_data e2prom_data;

fd = open("/dev/i2c-2",O_RDWR);
if(fd<0)
{
perror("open error\n");
}

e2prom_data.nmsgs = 2;
e2prom_data.msgs = (struct i2c_msg*)malloc(e2prom_data.nmsgs*sizeof(struct i2c_msg));
if(!e2prom_data.msgs)
{
perror("malloc error\n");
}
ioctl(fd,I2C_TIMEOUT,1);
ioctl(fd,I2C_RETRIES,2);

/* e2prom_data.nmsgs = 1;
(e2prom_data.msgs[0]).len = 2;
(e2prom_data.msgs[0]).addr = 0x50;
(e2prom_data.msgs[0]).flags = 0;
(e2prom_data.msgs[0]).buf = (unsigned char*)malloc(2);
(e2prom_data.msgs[0]).buf[0] = 0x10;
(e2prom_data.msgs[0]).buf[1] = 0x58;

ret = ioctl(fd,I2C_RDWR,(unsigned long)&e2prom_data);

if(ret < 0)
{
perror("ioctl error1");
}

sleep(1);
*/

e2prom_data.nmsgs = 2;
(e2prom_data.msgs[0]).len = 1;
(e2prom_data.msgs[0]).addr = 0x64;
(e2prom_data.msgs[0]).flags = 0;
(e2prom_data.msgs[0]).buf = (unsigned char*)malloc(1);
(e2prom_data.msgs[0]).buf[0] = 0x02;

(e2prom_data.msgs[1]).len = 2;
(e2prom_data.msgs[1]).addr = 0x64;
(e2prom_data.msgs[1]).flags = I2C_M_RD;
(e2prom_data.msgs[1]).buf = (unsigned char*)malloc(2);
(e2prom_data.msgs[1]).buf[0] = 0;
(e2prom_data.msgs[1]).buf[1] = 0;

ret = ioctl(fd,I2C_RDWR,(unsigned long)&e2prom_data);
if(ret<0)
{
perror("ioctl error2");
}

printf("buf[0] = %x\n",(e2prom_data.msgs[1]).buf[0]);
printf("buf[1] = %x\n",(e2prom_data.msgs[1]).buf[1]);

free((e2prom_data.msgs[1]).buf);
free(e2prom_data.msgs);

close(fd);

return 0;
}

这是我的代码

使用的板子是imx6q

要读取的设备是ltc2941库仑计
设备是接到i2c3上面的  设备节点应该就是i2c-2

The 7-bit
hard-coded I2C address of LTC2941 is 1100100.

这个是从设备地址

addr
02h C Accumulated Charge MSB       R/W             7Fh
03h D Accumulated Charge LSB          R/W             FFh

这个是我要读取的设备寄存器的地址

我在板子上面运行之后报 ioctl error2：input/output error
我程序地址有没有什么问题  我现在就是不知道报这个错误是因为这个设备没接对还是设备已经挂上i2c了我在读写的时候错了

有没有写过的先帮我看看代码有没有问题 0.0

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