Linux ARM I2C 通讯读数据

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

// #define I2C_RETRIES 0x0701
// #define I2C_TIMEOUT 0x0702
// #define I2C_RDWR 0x0707
/*********定义struct i2c_rdwr_ioctl_data和struct i2c_msg，要和内核一致*******/

/***********主程序***********/
int main()
{
    int fd, ret, i;
    char s_Dev[] = "/dev/i2c-1";
    unsigned char s_Write[4];
    unsigned char s_Read[4];
    unsigned char device_addr = 0x40; /*  设备地址 */
                                      //  struct i2c_rdwr_ioctl_data msg_rdwr;
    struct i2c_msg i2cmsg[2];
    fd = open(s_Dev, O_RDWR);
    /*      dev / i2c - 0是在注册i2c - dev.c后产生的，代表一个可操作的适配器。如果不使用i2c - dev.c *的方式，就没有，也不需要这个节点。 */
    if (fd < 0)
    {
        printf("open failed [%s]\n", s_Dev);
        perror("open error");
        return 0;
    }
    printf("open  ok ![%s]\n", s_Dev);

    //  e2prom_data.nmsgs = 2;
    // /*
    //  *因为操作时序中，最多是用到2个开始信号（字节读操作中），所以此将
    //  *e2prom_data.nmsgs配置为2
    //  */
    struct i2c_rdwr_ioctl_data msg_rdwr; // = {.msgs = i2cmsg, .nmsgs = 2};
    msg_rdwr.msgs = i2cmsg;
    msg_rdwr.nmsgs = 2;
    // e2prom_data.msgs = (struct i2c_msg *)malloc(e2prom_data.nmsgs * sizeof(struct i2c_msg));
    // if (!e2prom_data.msgs)
    // {
    //     printf("malloc error ![%s]\n", s_Dev);
    //     perror("malloc error");
    //     exit(1);
    // }
    ioctl(fd, I2C_TIMEOUT, 1); /*超时时间*/
    ioctl(fd, I2C_RETRIES, 2); /*重复次数*/

    // msg_rdwr.msgs = i2cmsg;
    // msg_rdwr.nmsgs = 2;

    /***write data to e2prom**/
    s_Write[0] = 0xe3;
    s_Write[1] = 0;
    // e2prom_data.nmsgs = 1;
    // (e2prom_data.msgs[0]).len = strlen(s_Write); // 1个 e2prom 写入目标的地址和1个数据
    // (e2prom_data.msgs[0]).addr = device_addr;    // e2prom 设备地址
    // (e2prom_data.msgs[0]).flags = 0;             // write
    // (e2prom_data.msgs[0]).buf = s_Write;         //(unsigned char *)malloc(2);
    //                                              // (e2prom_data.msgs[0]).buf[0] = 0x10; // e2prom 写入目标的地址
    //                                              //  (e2prom_data.msgs[0]).buf[1] = 0x58; // the data to write
    msg_rdwr.msgs[0].addr = device_addr;    // e2prom 设备地址
    msg_rdwr.msgs[0].flags = 0;             // write
    msg_rdwr.msgs[0].buf = s_Write;         // e2prom数据地址
    msg_rdwr.msgs[0].len = strlen(s_Write); // e2prom 目标数据的地址

    msg_rdwr.msgs[1].addr = device_addr;   // e2prom 设备地址
    msg_rdwr.msgs[1].flags = 1;            // read
    msg_rdwr.msgs[1].buf = s_Read;         //(unsigned char *)malloc(1); //存放返回值的地址。
    msg_rdwr.msgs[1].len = strlen(s_Read); //读出的数据
    printf("s_Write  \n msgs:  ");
    for (i = 0; i < strlen(s_Write); i++)
        printf("%.2X ", s_Write[i]);
    printf("\n");
    printf("s_Read  \n msgs:  ");
    for (i = 0; i < strlen(s_Read); i++)
        printf("%.2X ", s_Read[i]);
    printf("\n");
    ret = ioctl(fd, I2C_RDWR, (unsigned long)&msg_rdwr);

    if (ret < 0)
    {
        perror("ioctl error1");
    }
    ret = 256 * s_Read[0] + s_Read[1];
    float f_Temp = -46.85 + 175.7 * ret / 0x10000;
    printf("Temperature----: %f(%d, %d, %d)\n", f_Temp, s_Read[0], s_Read[1], s_Read[2]);
    sleep(1);
    /******read data from e2prom*******/
    s_Write[0] = 0xe5;
    s_Write[1] = 0;

    msg_rdwr.msgs[0].addr = device_addr;    // e2prom 设备地址
    msg_rdwr.msgs[0].flags = 0;             // write
    msg_rdwr.msgs[0].buf = s_Write;         // e2prom数据地址
    msg_rdwr.msgs[0].len = strlen(s_Write); // e2prom 目标数据的地址

    msg_rdwr.msgs[1].addr = device_addr;   // e2prom 设备地址
    msg_rdwr.msgs[1].flags = 1;            // read
    msg_rdwr.msgs[1].buf = s_Read;         //(unsigned char *)malloc(1); //存放返回值的地址。
    msg_rdwr.msgs[1].len = strlen(s_Read); //读出的数据

    ret = ioctl(fd, I2C_RDWR, (unsigned long)&msg_rdwr);
    if (ret < 0)
    {
        perror("ioctl error2");
    }
    // printf("buff[0]=%x\n", (e2prom_data.msgs[1]).buf[0]);
    ret = 256 * s_Read[0] + s_Read[1];
    f_Temp = 6.0 + 125.0 * ret / 0x10000;
    printf("Humidity------: %f(%d, %d, %d)\n", f_Temp, s_Read[0], s_Read[1], s_Read[2]);

    /***打印读出的值，没错的话，就应该是前面写的0x58了***/
    close(fd);
    return 0;
}

#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define CHIP "/dev/i2c-1"
#define I2C_DEVICE_ADDR 0x40 // eeprom addr

static int iic_write(int i2c_fd, int device_addr, unsigned int reg_address, unsigned int reg_val)
{
    struct i2c_rdwr_ioctl_data work_queue;
    int ret = 0;

    work_queue.nmsgs = 1;
    work_queue.msgs = (struct i2c_msg *)malloc(work_queue.nmsgs * sizeof(struct i2c_msg));
    if (!work_queue.msgs)
    {
        printf("msgs memery alloc error\n");
        close(i2c_fd);
        return -1;
    }
    if ((work_queue.msgs[0].buf = (unsigned char *)malloc(2 * sizeof(unsigned char))) == NULL)
    {
        printf("buf memery alloc error...\n");
        close(i2c_fd);
        return -1;
    }

    (work_queue.msgs[0]).len = 2;
    (work_queue.msgs[0]).flags = !I2C_M_RD;
    (work_queue.msgs[0]).addr = device_addr;
    (work_queue.msgs[0]).buf[0] = reg_address;
    (work_queue.msgs[0]).buf[1] = reg_val;

    work_queue.nmsgs = 1;

    ret = ioctl(i2c_fd, I2C_RDWR, (unsigned long)&work_queue);
    if (ret < 0)
    {
        printf("Error during I2C_RDWR ioctl with error code: %d\n", ret);
        return -1;
    }

    free(work_queue.msgs[0].buf);
    free(work_queue.msgs);

    return 0;
}

static int iic_read(int i2c_fd, int device_addr, unsigned int reg_address)
{
    struct i2c_rdwr_ioctl_data work_queue;
    unsigned char val;
    int ret;

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

    if (!work_queue.msgs)
    {
        printf("Memery alloc error\n");
        close(i2c_fd);
        return -1;
    }

    val = (unsigned char)reg_address;

    (work_queue.msgs[0]).len = 1;
    (work_queue.msgs[0]).flags = 0;// write
    (work_queue.msgs[0]).addr = device_addr;// 设备地址
    (work_queue.msgs[0]).buf = &val;

    (work_queue.msgs[1]).len = 1;
    (work_queue.msgs[1]).flags = 1;// read
    (work_queue.msgs[1]).addr = device_addr;// 设备地址
    (work_queue.msgs[1]).buf = &val;

    ret = ioctl(i2c_fd, I2C_RDWR, (unsigned long)&work_queue);
    if (ret < 0)
    {
        printf("Error during I2C_RDWR ioctl with error code: %d\n", ret);
        return -1;
    }

    free(work_queue.msgs);

    return val;
}

int main()
{
    printf("hello, this is i2c test\n");
    int ret = 0;
    int ik;
    int fd = open(CHIP, O_RDWR);

    if (fd < 0)
    {
        printf("open %s failed\n", CHIP);
        goto exit;
    }

    if (ioctl(fd, I2C_SLAVE, I2C_DEVICE_ADDR) < 0)
    { // device addr
        printf("ioictl: set slave address failed\n");
        goto close;
    }

    // ret = iic_write(fd, I2C_DEVICE_ADDR, 0, 0xaa);
    // if (ret)
    //     printf("write failed\n");

    // usleep(1000 * 1000 * 0.1);

    // ret = iic_write(fd, I2C_DEVICE_ADDR, 1, 0xbb);
    // if (ret)
    //     printf("write failed\n");

    usleep(1000 * 1000 * 0.1);

    ret = iic_read(fd, I2C_DEVICE_ADDR, 0xe3);
    printf("read reg addr:0 data:%x\n", ret);
    ret = 256 * ret;
    float f_Temp = -46.85 + 175.7 * ret / 0x10000;
    printf("Temperature----: %f)\n", f_Temp);
    ret = iic_read(fd, I2C_DEVICE_ADDR, 0xe5);
    printf("read reg addr:1 data:%x\n", ret);
    ret = 256 * ret;
    f_Temp = 6.0 + 125.0 * ret / 0x10000;
    printf("Humidity------: %f\n", f_Temp);

close:
    close(fd);

exit:
    return 0;
}

 上述是两个文件，分别执行的结果如上，记录下经历， 是读，写没有测试环境，没有测试。