RTT 模拟I2C 框架接口问题

发布于 2023-09-22 10:59:15 浏览：709 订阅该版

```c
rt_err_t at24cxx_write_one_byte(at24cxx_device_t dev, uint16_t writeAddr, uint8_t dataToWrite)
{

rt_kprintf("at24cxx_write_one_byte() WriteAddr = %d\r\n ",writeAddr);
    rt_uint8_t buf[3];
#if (EE_TYPE > AT24C16)
    buf[0] = (uint8_t)(writeAddr>>8);
    buf[1] = (uint8_t)writeAddr;
    buf[2] = dataToWrite;
    if (rt_i2c_master_send(dev->i2c, AT24CXX_ADDR, 0, buf, 3) == 3)
#else
    dev->AddrInput = (writeAddr >> 8); //增加这么一句话，根据读取地址，自动计算页地址A2A1A0
    rt_kprintf("at24cxx_write_one_byte /writeaddr =%d ,AddrInput = %d , AT24CXX_ADDR|dev->AddrInput = %d\r\n",writeAddr,dev->AddrInput,(AT24CXX_ADDR | dev->AddrInput) );
    buf[0] = writeAddr; //cmd
    buf[1] = dataToWrite;

//buf[2] = data[1];

if (rt_i2c_master_send(dev->i2c, (AT24CXX_ADDR | dev->AddrInput), 0, buf, 2) == **1**) **//源代码设置是2**
#endif
        return RT_EOK;
    else
        return -RT_ERROR;

}
```

```c
rt_size_t rt_i2c_master_send(struct rt_i2c_bus_device *bus,
                             rt_uint16_t               addr,
                             rt_uint16_t               flags,
                             const rt_uint8_t         *buf,
                             rt_uint32_t               count)
{
    rt_size_t ret;
    struct rt_i2c_msg msg;

msg.addr  = addr;
    msg.flags = flags;
    msg.len   = count;
    msg.buf   = (rt_uint8_t *)buf;

** ret = rt_i2c_transfer(bus, &msg, 1);**
    rt_kprintf("rt_i2c_master_send() ret = %d\r\n",ret);
    return ret;
}
```
rt_i2c_master_send and rt_i2c_transfer 这两个接口的返回值怎么理解，官网没有详细描述这个返回值，基于AT24CXX driver测试AT24C512，发现，源代码at24cxx_write_one_byte 中的rt_i2c_master_send 接口第五个参数设置2，就会导致发送与接接收的不一致，改成1就好了