set_clock_latency -source -early 0.2 [get_clocks sysClk] set_clock_latency -source -late 0.5 [get_clocks sysClk]

这是两个例子，用于设置时钟sysClk的时延。第一条命令"set_clock_latency -source -early 0.2 [get_clocks sysClk]"表示将时钟sysClk的时延提前0.2个时钟周期，即在时钟上升沿之前0.2个时钟周期的时刻触发相关逻辑。第二条命令"set_clock_latency -source -late 0.5 [get_clocks sysClk]"表示将时钟sysClk的时延推迟0.5个时钟周期，即在时钟上升沿之后0.5个时钟周期的时刻触发相关逻辑。这两个命令可以用于调整时钟与其他信号之间的时序关系，以满足设计的时序要求。

相关问题

HAL_Transmit_DMA如何使用

HAL_Transmit_DMA()函数是HAL库中用于启动DMA传输的函数。使用该函数可以将数据从内存传输到外设，而无需CPU的干预。下面是使用HAL_Transmit_DMA()函数的步骤：

1.在代码中包含相应的头文件，例如：#include "stm32f4xx_hal.h"。

2.定义DMA_HandleTypeDef结构体变量，例如：DMA_HandleTypeDef hdma_usart1_tx;。

3.在HAL_UART_Transmit_DMA()函数前加上 extern DMA_HandleTypeDef hdma_usart1_tx;，以便在函数中使用hdma_usart1_tx变量。

4.在main()函数中初始化hdma_usart1_tx变量，例如：hdma_usart1_tx.Instance = DMA2_Stream7; hdma_usart1_tx.Init.Channel = DMA_CHANNEL_4; hdma_usart1_tx.Init.Direction = DMA_MEMORY_TO_PERIPH; hdma_usart1_tx.Init.PeriphInc = DMA_PINC_DISABLE; hdma_usart1_tx.Init.MemInc = DMA_MINC_ENABLE; hdma_usart1_tx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE; hdma_usart1_tx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE; hdma_usart1_tx.Init.Mode = DMA_NORMAL; hdma_usart1_tx.Init.Priority = DMA_PRIORITY_LOW; hdma_usart1_tx.Init.FIFOMode = DMA_FIFOMODE_DISABLE; hdma_usart1_tx.Init.FIFOThreshold = DMA_FIFO_THRESHOLD_FULL; hdma_usart1_tx.Init.MemBurst = DMA_MBURST_SINGLE; hdma_usart1_tx.Init.PeriphBurst = DMA_PBURST_SINGLE; HAL_DMA_Init(&hdma_usart1_tx);

5.在每次需要调用 HAL_UART_Transmit_DMA()函数前通过if((&huart1)->gState == HAL_UART_STATE_READY) 判断一下是否准备好了发送。

6.调用HAL_UART_Transmit_DMA()函数，例如：HAL_UART_Transmit_DMA(&huart1, (uint8_t *)aTxBuffer, TXBUFFERSIZE);

下面是一个完整的例子：

#include "stm32f4xx_hal.h"

/* Private variables ---------------------------------------------------------*/
UART_HandleTypeDef huart1;DMA_HandleTypeDef hdma_usart1_tx;

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_DMA_Init(void);
static void MX_USART1_UART_Init(void);

/* Private functions ---------------------------------------------------------*/

int main(void)
{
  /* MCU Configuration--------------------------------------------------------*/

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();

  /* Configure the system clock */
  SystemClock_Config();

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_DMA_Init();
  MX_USART1_UART_Init();

  /* USER CODE BEGIN 2 */
  char aTxBuffer[] = "Hello World!";
  uint16_t TXBUFFERSIZE = strlen(aTxBuffer);
  if((&huart1)->gState == HAL_UART_STATE_READY)
  {
    HAL_UART_Transmit_DMA(&huart1, (uint8_t *)aTxBuffer, TXBUFFERSIZE);
  }
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
  /* USER CODE END WHILE */

  /* USER CODE BEGIN 3 */

  }
  /* USER CODE END 3 */
}

/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
}

/**
  * @brief USART1 Initialization Function
  * @param None
  * @retval None
  */
static void MX_USART1_UART_Init(void)
{

  /* USER CODE BEGIN USART1_Init 0 */

  /* USER CODE END USART1_Init 0 */

  /* USER CODE BEGIN USART1_Init 1 */

  /* USER CODE END USART1_Init 1 */
  huart1.Instance = USART1;
  huart1.Init.BaudRate = 115200;
  huart1.Init.WordLength = UART_WORDLENGTH_8B;
  huart1.Init.StopBits = UART_STOPBITS_1;
  huart1.Init.Parity = UART_PARITY_NONE;
  huart1.Init.Mode = UART_MODE_TX_RX;
  huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart1.Init.OverSampling = UART_OVERSAMPLING_16;
  if (HAL_UART_Init(&huart1) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN USART1_Init 2 */

  /* USER CODE END USART1_Init 2 */

}

/**
  * Enable DMA controller clock
  */
static void MX_DMA_Init(void)
{

  /* DMA controller clock enable */
  __HAL_RCC_DMA2_CLK_ENABLE();

  /* DMA interrupt init */
  /* DMA2_Stream7_IRQn interrupt configuration */
  HAL_NVIC_SetPriority(DMA2_Stream7_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(DMA2_Stream7_IRQn);

}

/**
  * @brief GPIO Initialization Function
  * @param None
  * @retval None
  */
static void MX_GPIO_Init(void)
{

  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOH_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();

}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */
  while(1)
  {
  }
  /* USER CODE END Error_Handler_Debug */
}

#ifdef  USE_FULL_ASSERT

/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @param  file: pointer to the source file name
  * @param  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}

#endif

HAL_UARTEx_ReceiveToIdle_DMA示例

以下是HAL_UARTEx_ReceiveToIdle_DMA的示例代码：

/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "stm32f4xx_hal.h"

/* Private variables ---------------------------------------------------------*/
UART_HandleTypeDef huart2;
DMA_HandleTypeDef hdma_usart2_rx;

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_DMA_Init(void);
static void MX_USART2_UART_Init(void);

/* Private functions ---------------------------------------------------------*/

/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
  HAL_Init();

  /* Configure the system clock */
  SystemClock_Config();

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_DMA_Init();
  MX_USART2_UART_Init();

  uint8_t buffer[100] = {0};
  uint32_t rx_size;

  while (1)
  {
    // Start UART reception in DMA mode until idle
    HAL_UARTEx_ReceiveToIdle_DMA(&huart2, buffer, sizeof(buffer));

    // Wait until idle
    while (HAL_UARTEx_GetRxIdleness(&huart2) != RESET);

    // Get received data size
    rx_size = sizeof(buffer) - __HAL_DMA_GET_COUNTER(&hdma_usart2_rx);

    // Process received data
    // ...

    // Clear buffer
    memset(buffer, 0, sizeof(buffer));
  }
}

/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
}

/**
  * @brief USART2 Initialization Function
  * @param None
  * @retval None
  */
static void MX_USART2_UART_Init(void)
{
  huart2.Instance = USART2;
  huart2.Init.BaudRate = 115200;
  huart2.Init.WordLength = UART_WORDLENGTH_8B;
  huart2.Init.StopBits = UART_STOPBITS_1;
  huart2.Init.Parity = UART_PARITY_NONE;
  huart2.Init.Mode = UART_MODE_TX_RX;
  huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart2.Init.OverSampling = UART_OVERSAMPLING_16;
  huart2.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart2.Init.ClockPrescaler = UART_PRESCALER_DIV1;
  huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_UART_Init(&huart2) != HAL_OK)
  {
    Error_Handler();
  }
}

/**
  * Enable DMA controller clock
  */
static void MX_DMA_Init(void)
{
  /* DMA controller clock enable */
  __HAL_RCC_DMA1_CLK_ENABLE();

  /* DMA interrupt init */
  /* DMA1_Stream5_IRQn interrupt configuration */
  HAL_NVIC_SetPriority(DMA1_Stream5_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(DMA1_Stream5_IRQn);
}

/**
  * @brief GPIO Initialization Function
  * @param None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOH_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOD_CLK_ENABLE();
}

/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* User may add here some code to deal with this error */
  while(1)
  {
  }
}

/**
  * @brief  This function is executed in case of DMA interrupt occurrence.
  * @retval None
  */
void DMA1_Stream5_IRQHandler(void)
{
  HAL_DMA_IRQHandler(&hdma_usart2_rx);
}

/**
  * @brief  This function is executed when DMA reception is completed.
  * @param  huart: UART handle
  * @retval None
  */
void HAL_UARTEx_RxEventCallback(UART_HandleTypeDef *huart)
{
  if (huart->Instance == USART2)
  {
    // DMA reception completed, do something if needed
  }
}

在此示例代码中，我们使用STM32Cube HAL库实现了UART的DMA接收，使用了HAL_UARTEx_ReceiveToIdle_DMA函数。在主循环中，我们不断调用该函数以启动DMA接收，然后等待DMA接收完成。一旦接收完成，我们就可以对接收到的数据进行处理。注意，在处理完数据后，我们需要清空接收缓冲区，以便下一次接收。