5 i2c通信rt_i2c_master_send实际写入地址比真正的传感器地址右移一位，为什么

发布于 2024-09-10 16:14:39 浏览：423 订阅该版

```c
#define MAG_I2C_ADDRESS           (0x18)

rt_err_t rt_i2c00_config(char* i2c_device_name)
{
		rt_err_t res = RT_EOK;
    i2c_device = rt_device_find(i2c_device_name);
    if(i2c_device == RT_NULL)
    {
        LOG_E("i2c0 device %s not found!\r\n", i2c_device_name);
        return -RT_EEMPTY;
    }	
		return res;
}

static rt_err_t write_multi_data(rt_uint8_t *buf, rt_uint8_t len)
{
    if(rt_i2c_master_send((struct rt_i2c_bus_device*)i2c_device, MAG_I2C_ADDRESS, RT_I2C_WR, buf, len) == len)
		return RT_EOK;
		else return RT_ERROR;
}

static rt_err_t st480_init(rt_device_t dev)
{
		rt_err_t res = RT_EOK;
	  uint8_t config_buf_1[4] = {0x60,0x00,0x7C,0x00};
		uint8_t config_buf_2[4] = {0x60,0x00,0x18,0x08};

/* init iic bus */
	  rt_device_open(i2c_device , RT_DEVICE_OFLAG_RDWR);

res |= write_multi_data(config_buf_1,4);
		if(res)  LOG_E("err, write_multi_data(config_buf_1,4)");	
		res |= write_multi_data(config_buf_2,4);
		if(res)  LOG_E("err, write_multi_data(config_buf_2,4))");
	
		LOG_D("st480 init finish\r\n");
	  return res;
}

```
![0c02b9247093583a4b4af33b965962afbf0d819a3d320bb9401035a7e9aed7e6QzpcVXNlcnNcenpcQXBwRGF0YVxSb2FtaW5nXERpbmdUYWxrXDMyMTcxNDY0X3YyXEltYWdlRmlsZXNcMTcyNTk1NTY4NTM2M19FQzBCRDEzQi01QTM0LTQ5NmQtODVFQi1FRDA2NTc2QjFGMTMucG5n.png](https://oss-club.rt-thread.org/uploads/20240910/2182a53bdf54a4f6465b28a9db28fa6c.png.webp)
![fe8b86f5e54e275169dfc0b9d5a1f880b81d71af0bda9a4b39b7dd5eaaa96053QzpcVXNlcnNcenpcQXBwRGF0YVxSb2FtaW5nXERpbmdUYWxrXDMyMTcxNDY0X3YyXEltYWdlRmlsZXNcMTcyNTk1NTYzMjk1OF9BRjhBOTdBMS05MUQyLTRmZTgtOThBRC0wMzZGQUEyNzgxNDMucG5n.png](https://oss-club.rt-thread.org/uploads/20240910/aea2e077df0b9f08fd0a8429b3e00642.png)

地磁传感器st480地址是0x18,可为什么实际输出是0x30呢，恰好是0x18左移一位，我试着将传感器地址改为右移一位：

```c
#define MAG_I2C_ADDRESS  (0x18>>1);
write_multi_data(config_buf_1,4);
```
就可以正常输出0x18,但后面`write_multi_data(config_buf_2,4);`依旧是输出0x30,
不知道为什么，是哪里配置不对么，为什么。