HAL_I2C_Mem_Read函数实现

HAL_I2C_Mem_Read 函数是基于 HAL 库和 STM32 的硬件 I2C 接口实现的，用于从 I2C 设备的指定寄存器中读取数据。下面是 HAL_I2C_Mem_Read 函数的具体实现：

HAL_StatusTypeDef HAL_I2C_Mem_Read(I2C_HandleTypeDef *hi2c, uint16_t DevAddress, uint16_t MemAddress, uint16_t MemAddSize, uint8_t *pData, uint16_t Size, uint32_t Timeout)
{
    HAL_StatusTypeDef status = HAL_OK;

    status = HAL_I2C_Mem_Read_IT(hi2c, DevAddress, MemAddress, MemAddSize, pData, Size);
    if (status != HAL_OK)
    {
        return status;
    }

    status = HAL_I2C_WaitReady(hi2c, Timeout);
    if (status != HAL_OK)
    {
        return status;
    }

    return HAL_OK;
}

HAL_StatusTypeDef HAL_I2C_Mem_Read_IT(I2C_HandleTypeDef *hi2c, uint16_t DevAddress, uint16_t MemAddress, uint16_t MemAddSize, uint8_t *pData, uint16_t Size)
{
    HAL_StatusTypeDef status = HAL_OK;

    if (hi2c->State == HAL_I2C_STATE_READY)
    {
        hi2c->State = HAL_I2C_STATE_BUSY_TX;
        hi2c->ErrorCode = HAL_I2C_ERROR_NONE;

        hi2c->pBuffPtr = pData;
        hi2c->XferCount = Size;
        hi2c->XferSize = Size;
        hi2c->MemAddress = MemAddress;
        hi2c->MemAddSize = MemAddSize;
        hi2c->DevAddress = DevAddress;
        hi2c->XferDirection = I2C_DIRECTION_RECEIVE;

        status = I2C_RequestMemoryRead(hi2c);
        if (status != HAL_OK)
        {
            hi2c->State = HAL_I2C_STATE_READY;
            hi2c->ErrorCode |= HAL_I2C_ERROR_REQUEST;
        }
        else
        {
            hi2c->State = HAL_I2C_STATE_BUSY_RX;
        }
    }
    else
    {
        status = HAL_BUSY;
    }

    return status;
}

HAL_StatusTypeDef HAL_I2C_WaitReady(I2C_HandleTypeDef *hi2c, uint32_t Timeout)
{
    uint32_t tickstart = HAL_GetTick();

    while (hi2c->State != HAL_I2C_STATE_READY)
    {
        if ((Timeout != HAL_MAX_DELAY) && ((HAL_GetTick() - tickstart) >= Timeout))
        {
            hi2c->State = HAL_I2C_STATE_READY;
            hi2c->ErrorCode |= HAL_I2C_ERROR_TIMEOUT;
            return HAL_TIMEOUT;
        }
    }

    return HAL_OK;
}

HAL_I2C_Mem_Read 函数首先调用了 HAL_I2C_Mem_Read_IT 函数，该函数负责向 I2C 设备发出读取指定寄存器的请求，然后等待 I2C 设备的响应。如果读取成功，函数会返回 HAL_OK；否则，函数会返回错误码。如果读取操作未完成，HAL_I2C_Mem_Read 函数将等待 I2C 设备的响应，直到超时或者读取完成为止。

HAL_I2C_Mem_Read_IT 函数主要负责设置 I2C 设备的读取参数，然后向 I2C 设备发出读取指定寄存器的请求。如果读取请求成功，函数会返回 HAL_OK；否则，函数会返回错误码。

HAL_I2C_WaitReady 函数用于等待 I2C 设备的响应。如果 I2C 设备未响应，函数将返回超时错误码 HAL_TIMEOUT；如果 I2C 设备的响应已经完成，函数将返回 HAL_OK。