stm32用dma方式从串口输出实验流程图

以下是基于STM32CubeIDE的DMA方式从串口输出的实验流程图：

1. 初始化串口和DMA模块
2. 配置DMA通道，设置传输方向为从内存到外设
3. 配置DMA传输大小和传输数据的存储地址
4. 启动DMA传输
5. 等待DMA传输完成
6. 关闭DMA传输
7. 重复步骤3-6，直到完成所有需要输出的数据
8. 关闭串口

下面是一个简单的代码示例，用于在STM32上使用DMA方式从串口输出数据：

#include "stm32f4xx.h"
#include "stm32f4xx_hal.h"

#define USART_TX_BUFFER_SIZE 64

UART_HandleTypeDef huart;
DMA_HandleTypeDef hdma_usart_tx;

uint8_t usart_tx_buffer[USART_TX_BUFFER_SIZE] = "Hello, world!\n";

void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_DMA_Init(void);
static void MX_USART2_UART_Init(void);

int main(void)
{
  HAL_Init();
  SystemClock_Config();
  MX_GPIO_Init();
  MX_DMA_Init();
  MX_USART2_UART_Init();

  HAL_UART_Transmit_DMA(&huart, usart_tx_buffer, USART_TX_BUFFER_SIZE);

  while (1)
  {
  }
}

void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  __HAL_RCC_PWR_CLK_ENABLE();
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE1);

  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
  RCC_OscInitStruct.PLL.PLLM = 16;
  RCC_OscInitStruct.PLL.PLLN = 336;
  RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV4;
  RCC_OscInitStruct.PLL.PLLQ = 7;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_SYSCLK | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_5) != HAL_OK)
  {
    Error_Handler();
  }
}

static void MX_USART2_UART_Init(void)
{
  huart.Instance = USART2;
  huart.Init.BaudRate = 115200;
  huart.Init.WordLength = UART_WORDLENGTH_8B;
  huart.Init.StopBits = UART_STOPBITS_1;
  huart.Init.Parity = UART_PARITY_NONE;
  huart.Init.Mode = UART_MODE_TX_RX;
  huart.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart.Init.OverSampling = UART_OVERSAMPLING_16;
  if (HAL_UART_Init(&huart) != HAL_OK)
  {
    Error_Handler();
  }
}

static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};

  __HAL_RCC_GPIOA_CLK_ENABLE();

  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_5, GPIO_PIN_RESET);

  GPIO_InitStruct.Pin = GPIO_PIN_5;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
}

static void MX_DMA_Init(void)
{
  __HAL_RCC_DMA1_CLK_ENABLE();

  hdma_usart_tx.Instance = DMA1_Stream6;
  hdma_usart_tx.Init.Channel = DMA_CHANNEL_4;
  hdma_usart_tx.Init.Direction = DMA_MEMORY_TO_PERIPH;
  hdma_usart_tx.Init.PeriphInc = DMA_PINC_DISABLE;
  hdma_usart_tx.Init.MemInc = DMA_MINC_ENABLE;
  hdma_usart_tx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;
  hdma_usart_tx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;
  hdma_usart_tx.Init.Mode = DMA_NORMAL;
  hdma_usart_tx.Init.Priority = DMA_PRIORITY_LOW;
  hdma_usart_tx.Init.FIFOMode = DMA_FIFOMODE_DISABLE;
  if (HAL_DMA_Init(&hdma_usart_tx) != HAL_OK)
  {
    Error_Handler();
  }

  __HAL_LINKDMA(&huart, hdmatx, hdma_usart_tx);

  HAL_NVIC_SetPriority(DMA1_Stream6_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(DMA1_Stream6_IRQn);
}

void DMA1_Stream6_IRQHandler(void)
{
  HAL_DMA_IRQHandler(&hdma_usart_tx);
}

void Error_Handler(void)
{
}

在这个示例中，我们使用DMA传输从内存中的缓冲区向USART2外设发送数据。首先，在 `MX_DMA_Init()` 函数中，我们初始化DMA传输并设置传输方向为从内存到外设。然后，在 `MX_USART2_UART_Init()` 函数中，我们初始化USART2外设。最后，在 `main()` 函数中，我们调用 `HAL_UART_Transmit_DMA()` 函数来启动DMA传输，并在 `while(1)` 循环中等待传输完成。