STM32初始化串口重定向后调试信息不输出的问题
@@ Author：明月清了个风
@@ Date： 2025/9/9
@@ PS：开发stm32F745的过程中发现printf有时候不打印信息，单独调试确定了串口初始化和重定向正确，但是在系统整体调试的时候虽然正确运行了却没有打印，通过使用本文所记录的方法暂时解决，但并不确定是否是最正确的解决方案，记录一下以供参考
内容结构如下：
- 问题现象及最终解决方法
一.问题现象及最终解决方法
现象如简介所述，确认初始化正确，重定向正确，资源分配正确，解决方法如下，在初始化时加入这行代码
setvbuf(stdout, NULL, _IONBF, 0);
表示无缓冲输出，但会增加系统调用的次数
下面贴出串口的初始化代码，应该没有错误
void hal_debug_usart_init(void)
{GPIO_InitTypeDef GPIO_InitStruct = {0};RCC_PeriphCLKInitTypeDef RCC_PeriphClkInit;// debug串口3时钟源配置RCC_PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART3;RCC_PeriphClkInit.Usart1ClockSelection = RCC_USART3CLKSOURCE_SYSCLK;HAL_RCCEx_PeriphCLKConfig(&RCC_PeriphClkInit);// 使能串口3时钟DEBUG_USART_CLK_ENABLE();// 使能串口3引脚时钟---GPIOCDEBUG_USART_RX_GPIO_CLK_ENABLE();DEBUG_USART_TX_GPIO_CLK_ENABLE();// 串口3收发引脚配置GPIO_InitStruct.Pin = DEBUG_USART_TX_PIN | DEBUG_USART_RX_PIN;GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;GPIO_InitStruct.Pull = GPIO_NOPULL;GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;GPIO_InitStruct.Alternate = GPIO_AF7_USART3;HAL_GPIO_Init(DEBUG_USART_PORT, &GPIO_InitStruct);// 配置串口3模式huart3.Instance = USART3;huart3.Init.BaudRate = 115200;huart3.Init.WordLength = UART_WORDLENGTH_8B;huart3.Init.StopBits = UART_STOPBITS_1;huart3.Init.Parity = UART_PARITY_NONE;huart3.Init.Mode = UART_MODE_TX_RX;huart3.Init.HwFlowCtl = UART_HWCONTROL_NONE;huart3.Init.OverSampling = UART_OVERSAMPLING_16;huart3.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;huart3.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;HAL_UART_Init(&huart3);HAL_NVIC_SetPriority(USART3_IRQn, 9, 0);HAL_NVIC_EnableIRQ(USART3_IRQn);
}void hal_debug_usart_dma_init(void)
{DEBUG_USART_DMA_CLK_ENABLE();/* DMA interrupt init *//* 串口3---DMA1-STREAM1接收 */HAL_NVIC_SetPriority(DMA1_Stream1_IRQn, 10, 0);HAL_NVIC_EnableIRQ(DMA1_Stream1_IRQn);/* 串口3---DMA1-STREAM3发送 */HAL_NVIC_SetPriority(DMA1_Stream3_IRQn, 10, 0);HAL_NVIC_EnableIRQ(DMA1_Stream3_IRQn);hdma_usart3_rx.Instance = DMA1_Stream1;hdma_usart3_rx.Init.Channel = DMA_CHANNEL_4;hdma_usart3_rx.Init.Direction = DMA_PERIPH_TO_MEMORY;hdma_usart3_rx.Init.PeriphInc = DMA_PINC_DISABLE;hdma_usart3_rx.Init.MemInc = DMA_MINC_ENABLE;hdma_usart3_rx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;hdma_usart3_rx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;hdma_usart3_rx.Init.Mode = DMA_NORMAL;hdma_usart3_rx.Init.Priority = DMA_PRIORITY_HIGH;hdma_usart3_rx.Init.FIFOMode = DMA_FIFOMODE_DISABLE;HAL_DMA_DeInit(&hdma_usart3_rx);HAL_DMA_Init(&hdma_usart3_rx);__HAL_LINKDMA(&huart3, hdmarx, hdma_usart3_rx);hdma_usart3_tx.Instance = DMA1_Stream3;hdma_usart3_tx.Init.Channel = DMA_CHANNEL_4;hdma_usart3_tx.Init.Direction = DMA_MEMORY_TO_PERIPH;hdma_usart3_tx.Init.PeriphInc = DMA_PINC_DISABLE;hdma_usart3_tx.Init.MemInc = DMA_MINC_ENABLE;hdma_usart3_tx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;hdma_usart3_tx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;hdma_usart3_tx.Init.Mode = DMA_NORMAL;hdma_usart3_tx.Init.Priority = DMA_PRIORITY_LOW;hdma_usart3_tx.Init.FIFOMode = DMA_FIFOMODE_DISABLE;HAL_DMA_DeInit(&hdma_usart3_tx);HAL_DMA_Init(&hdma_usart3_tx);__HAL_LINKDMA(&huart3, hdmatx, hdma_usart3_tx);
}int fputc(int ch, FILE *f)
{/* 发送一个字节数据到串口DEBUG_USART */HAL_UART_Transmit(&huart3, (uint8_t *)&ch, 1, HAL_MAX_DELAY); return (ch);
}
