imx 1052 的i2c驱动实测有问题

发布于 2021-07-11 18:33:59 浏览：1504 订阅该版

实测库上1052的i2c 驱动有问题，读写`at24cxx eeprom`时  写入的值是正确的，读出时值是错误的

简单查看了一下驱动代码，分析原因如下：
```c
static rt_size_t imxrt_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                    struct rt_i2c_msg msgs[],
                                    rt_uint32_t num)
{
    struct imxrt_i2c_bus *imxrt_i2c;
    rt_size_t i;
    RT_ASSERT(bus != RT_NULL);
    imxrt_i2c = (struct imxrt_i2c_bus *) bus;

imxrt_i2c->msg = msgs;
    imxrt_i2c->msg_ptr = 0;
    imxrt_i2c->msg_cnt = num;
    imxrt_i2c->dptr = 0;

for (i = 0; i < num; i++)
    {
        if (imxrt_i2c->msg[i].flags & RT_I2C_RD)
        {
            if (LPI2C_MasterStart(imxrt_i2c->I2C, imxrt_i2c->msg[i].addr, kLPI2C_Write) != kStatus_Success) //这里使用了kLPI2C_Write 参数，但是并有重新发送读的器件地址，会导致时序错误
            {
                i = 0;
                break;
            }

while (LPI2C_MasterGetStatusFlags(imxrt_i2c->I2C) & kLPI2C_MasterNackDetectFlag)
            {
            }

if (LPI2C_MasterRepeatedStart(imxrt_i2c->I2C, imxrt_i2c->msg[i].addr, kLPI2C_Read) != kStatus_Success)
            {
                i = 0;
                break;
            }

if (LPI2C_MasterReceive(imxrt_i2c->I2C, imxrt_i2c->msg[i].buf, imxrt_i2c->msg[i].len) != kStatus_Success)
            {
                i = 0;
                break;
            }
        }
        else
        {
            if (LPI2C_MasterStart(imxrt_i2c->I2C, imxrt_i2c->msg[i].addr, kLPI2C_Write) != kStatus_Success)
            {
                i = 0;
                break;
            }

while (LPI2C_MasterGetStatusFlags(imxrt_i2c->I2C) & kLPI2C_MasterNackDetectFlag)
            {
            }

if (LPI2C_MasterSend(imxrt_i2c->I2C, imxrt_i2c->msg[i].buf, imxrt_i2c->msg[i].len) != kStatus_Success)
            {
                i = 0;
                break;
            }

if (LPI2C_MasterWaitForTxFifoAllEmpty(imxrt_i2c->I2C) != kStatus_Success)
            {
                i = 0;
                break;
            }
        }
    }

if (LPI2C_MasterStop(imxrt_i2c->I2C) != kStatus_Success)
    {
        i = 0;
    }

imxrt_i2c->msg = RT_NULL;
    imxrt_i2c->msg_ptr = 0;
    imxrt_i2c->msg_cnt = 0;
    imxrt_i2c->dptr = 0;

return i;
}
```

3 个回答

aozima 2021-07-11

调网络不抓包，调I2C等时序不上逻辑分析仪，就像电工不用万用表！多用整理的好的文字，比截图更省流量，还能在整理过程中思考。

emlsyx 2021-07-11

这家伙很懒，什么也没写！

手里没有逻辑分析仪，简单修改了一下代码，在手里的OK1050-C开发版和库上的**imxrt1052-fire-pro** 上测试通过了

修改：
```c
static rt_err_t imxrt_lpi2c_wait_fifo_empty(LPI2C_Type *base) //新增函数
{
    size_t tx_count = 0xFFU;
    size_t rx_count = 0xFFU;

/* Check master tx FIFO empty or not */
    LPI2C_MasterGetFifoCounts(base, &rx_count, &tx_count);
    while (tx_count && rx_count)
    {
        LPI2C_MasterGetFifoCounts(base, &rx_count, &tx_count);
    }

/* Check communicate with slave successful or not */
    if (LPI2C_MasterGetStatusFlags(base) & kLPI2C_MasterNackDetectFlag)
    {
        return RT_EEMPTY;
    }
    return RT_EOK;
}

static rt_size_t imxrt_i2c_mst_xfer(struct rt_i2c_bus_device *bus,
                                    struct rt_i2c_msg msgs[],
                                    rt_uint32_t num)
{
    struct imxrt_i2c_bus *imxrt_i2c;
    rt_size_t i;
    RT_ASSERT(bus != RT_NULL);
    imxrt_i2c = (struct imxrt_i2c_bus *) bus;

imxrt_i2c->msg = msgs;
    imxrt_i2c->msg_ptr = 0;
    imxrt_i2c->msg_cnt = num;
    imxrt_i2c->dptr = 0;

for (i = 0; i < num; i++)
    {
        if (imxrt_i2c->msg[i].flags & RT_I2C_RD)
        {
            if (LPI2C_MasterStart(imxrt_i2c->I2C, imxrt_i2c->msg[i].addr, kLPI2C_Read) != kStatus_Success)
            {
                i = 0;
                break;
            }

/* Check communicate with slave successful or not */
            if (RT_EOK != imxrt_lpi2c_wait_fifo_empty(imxrt_i2c->I2C))
            {
                i = 0;
                break;
            }

if (LPI2C_MasterReceive(imxrt_i2c->I2C, imxrt_i2c->msg[i].buf, imxrt_i2c->msg[i].len) != kStatus_Success)
            {
                i = 0;
                break;
            }
        }
        else
        {
            if (LPI2C_MasterStart(imxrt_i2c->I2C, imxrt_i2c->msg[i].addr, kLPI2C_Write) != kStatus_Success)
            {
                i = 0;
                break;
            }

/* Check communicate with slave successful or not */
            if (RT_EOK != imxrt_lpi2c_wait_fifo_empty(imxrt_i2c->I2C))
            {
                i = 0;
                break;
            }

if (LPI2C_MasterSend(imxrt_i2c->I2C, imxrt_i2c->msg[i].buf, imxrt_i2c->msg[i].len) != kStatus_Success)
            {
                i = 0;
                break;
            }
        }
    }

if (LPI2C_MasterStop(imxrt_i2c->I2C) != kStatus_Success)
    {
        i = 0;
    }

imxrt_i2c->msg = RT_NULL;
    imxrt_i2c->msg_ptr = 0;
    imxrt_i2c->msg_cnt = 0;
    imxrt_i2c->dptr = 0;

return i;
}
```

emlsyx 2021-07-11

这家伙很懒，什么也没写！

aozima 2021-07-12

调网络不抓包，调I2C等时序不上逻辑分析仪，就像电工不用万用表！多用整理的好的文字，比截图更省流量，还能在整理过程中思考。

emlsyx 2021-07-12

这家伙很懒，什么也没写！

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liuduanfei 2021-07-12

这家伙很懒，什么也没写！

123 认证专家 2021-07-12

这家伙很懒，什么也没写！

emlsyx 2021-07-12

这家伙很懒，什么也没写！

我是对着官方的SDK(2.9.1版本)的i2c轮询的例程改的，具体的错误原因原理我也没分析。。。

大概原因我用注释写在我发的那个代码后边了，现在库上那个i2c驱动在读的时候发了一个写的启动信号，但是没有发后续的写操作，比如这里：
```c
//这里使用了kLPI2C_Write 参数，但是并有发后续的读操作地址等等
if (LPI2C_MasterStart(imxrt_i2c->I2C, imxrt_i2c->msg[i].addr, kLPI2C_Write) != kStatus_Success) 
{...}
```
其实在设备层使用时，会先调用一次写操作，去发送要操作的地址，`rt_i2c_master_send(bus, dev_addr, RT_I2C_WR, addr_buf, addr_len);`，所以读的时候不需要发送读操作指令了，
另外简单追了一下lpi2c的源码，`LPI2C_MasterReceive`和`LPI2C_MasterSend`函数里边有等fifo空的操作，不需要在外边再次判断了

修改的地方就两个：
1.重写了之前的LPI2C_MasterWaitForTxFifoAllEmpty函数，修改成如下：
```c
static rt_err_t imxrt_lpi2c_wait_fifo_empty(LPI2C_Type *base)
{
    size_t tx_count = 0xFFU;
    size_t rx_count = 0xFFU;

/* Check master tx FIFO empty or not */
    LPI2C_MasterGetFifoCounts(base, &rx_count, &tx_count);
    while (tx_count || rx_count)
    {
        LPI2C_MasterGetFifoCounts(base, &rx_count, &tx_count);
    }
    /* Check communicate with slave successful or not */
    if (LPI2C_MasterGetStatusFlags(base) & kLPI2C_MasterNackDetectFlag)
    {
        return RT_EEMPTY;
    }
    return RT_EOK;
}
```
2.修改了LPI2C_MasterWaitForTxFifoAllEmpty 中for循环的处理，修改如下：
```c
for (i = 0; i < num; i++)
{
    if (imxrt_i2c->msg[i].flags & RT_I2C_RD)
    {
        if (LPI2C_MasterStart(imxrt_i2c->I2C, imxrt_i2c->msg[i].addr, kLPI2C_Read) != kStatus_Success)
        {
            i = 0;
            break;
        }

/* Check communicate with slave successful or not */
        if (RT_EOK != imxrt_lpi2c_wait_fifo_empty(imxrt_i2c->I2C))
        {
            i = 0;
            break;
        }

if (LPI2C_MasterReceive(imxrt_i2c->I2C, imxrt_i2c->msg[i].buf, imxrt_i2c->msg[i].len) != kStatus_Success)
        {
            i = 0;
            break;
        }
    }
    else
    {
        if (LPI2C_MasterStart(imxrt_i2c->I2C, imxrt_i2c->msg[i].addr, kLPI2C_Write) != kStatus_Success)
        {
            i = 0;
            break;
        }

/* Check communicate with slave successful or not */
        if (RT_EOK != imxrt_lpi2c_wait_fifo_empty(imxrt_i2c->I2C))
        {
            i = 0;
            break;
        }

if (LPI2C_MasterSend(imxrt_i2c->I2C, imxrt_i2c->msg[i].buf, imxrt_i2c->msg[i].len) != kStatus_Success)
        {
            i = 0;
            break;
        }
    }
}
```