Linux I2C:读取消息长度

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <linux/i2c-dev.h>
#include <sys/ioctl.h>
#include <unistd.h>

int main() {
    int file;
    char *bus = "/dev/i2c-1"; // 根据实际情况选择I2C总线
    if ((file = open(bus, O_RDWR)) < 0) {
        perror("Failed to open the i2c bus");
        return 1;
    }

    int addr = 0x50; // I2C设备地址
    if (ioctl(file, I2C_SLAVE, addr) < 0) {
        perror("Failed to acquire bus access and/or talk to slave");
        return 1;
    }

    // 发送读取长度的命令
    char cmd = 0x01; // 假设设备通过发送0x01命令来获取消息长度
    if (write(file, &cmd, 1) != 1) {
        perror("Failed to write to the i2c bus");
        return 1;
    }

    // 读取消息长度
    unsigned char length;
    if (read(file, &length, 1) != 1) {
        perror("Failed to read from the i2c bus");
        return 1;
    }

    printf("Message length: %d\n", length);

    close(file);
    return 0;
}