I2C 例程

概述

K230 芯片内部集成了 5 个 I2C 硬件模块，支持标准模式（100 kb/s）、快速模式（400 kb/s）以及高速模式（3.4 Mb/s）。这些模块非常适合在开发板上进行 I2C 通信，例如连接外设（如传感器或显示器）。I2C 通道的输出 IO 可通过 IOMUX 模块进行配置。

示例

以下示例展示了如何使用 I2C 4 模块读写数据的例子。

#include<stdio.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <fcntl.h>
#include <unistd.h>

#include <rtthread.h>
#include <rtdevice.h>


#define RT_I2C_DEV_CTRL_10BIT (0x800 + 0x01)
#define RT_I2C_DEV_CTRL_TIMEOUT (0x800 + 0x03)
#define RT_I2C_DEV_CTRL_RW (0x800 + 0x04)
#define RT_I2C_DEV_CTRL_CLK (0x800 + 0x05)

enum dm_i2c_msg_flags
{
    I2C_M_TEN           = 0x0010, /* ten-bit chip address */
    I2C_M_RD            = 0x0001, /* read data, from slave to master */
    I2C_M_STOP          = 0x8000, /* send stop after this message */
    I2C_M_NOSTART       = 0x4000, /* no start before this message */
    I2C_M_REV_DIR_ADDR  = 0x2000, /* invert polarity of R/W bit */
    I2C_M_IGNORE_NAK    = 0x1000, /* continue after NAK */
    I2C_M_NO_RD_ACK     = 0x0800, /* skip the Ack bit on reads */
    I2C_M_RECV_LEN      = 0x0400, /* length is first received byte */
    I2C_M_RESTART       = 0x0002, /* restart before this message */
    I2C_M_START         = 0x0004, /* start before this message */
};



typedef struct {
    uint16_t addr;
    uint16_t flags;
    uint16_t len;
    uint8_t *buf;
} i2c_msg_t;

typedef struct {
    i2c_msg_t *msgs;
    size_t number;
} i2c_priv_data_t;


int  main(int argc, char *argv[])
{
    int fd;
    char *name = "/dev/i2c4";
    rt_uint32_t spped=100000;

    if (argc >= 2)
        name = argv[1];

    if (argc >= 3)
        spped = atoi(argv[2]);

    fd = open(name, O_RDWR); //打开设备
    if (fd < 0 ){
        printf(" %s device open failed\n", name);
        return -1;
    }

    if (ioctl(fd, RT_I2C_DEV_CTRL_CLK, &spped) != RT_EOK){ //设置速率
        printf("set %s speed %d failed!\n", name, spped);
    }

    for (int i = 0x08; i < 0x78; i++){
        unsigned char data;
        i2c_msg_t msgs={i, I2C_M_RD, 1, &data};
        i2c_priv_data_t privdata={&msgs, 1};

        if (ioctl(fd, RT_I2C_DEV_CTRL_RW, &privdata) == 0){ //读写数据
            printf("find device at add 0x%02hx and data=%x\n", i, data);
        }
    }

    close(fd);
}

提示

有关 I2C 模块的详细接口和使用方法，请参考API文档