STM32F407USART2串口使用DMA接收不定长数据和DMA中断发送

        使用DMA通信的好处是&＃xff0c;不占用单片机资源&＃xff08;不像普通串口中断&＃xff0c;发送一个字节触发一次中断&＃xff0c;发送100个字节触发100次中断&＃xff1b;接收一个字节触发一次中断&＃xff0c;接收200个字节触发200次中断&＃xff09;&＃xff0c;数据接收完毕触发一次DMA中断&＃xff1b;发送数据完毕触发一次DMA中断。

        下图是STM32F407单片机DMA通道关系图。

#define USART2_DMA_RX_BUFFER_MAX_LENGTH (255)
#define USART2_DMA_TX_BUFFER_MAX_LENGTH (255)
uint8_t USART2_DMA_RX_Buffer[USART2_DMA_RX_BUFFER_MAX_LENGTH];
uint8_t USART2_DMA_TX_Buffer[USART2_DMA_TX_BUFFER_MAX_LENGTH];

1、USART2  TX DMA初始化程序

void USART2_DMA_Tx_Configuration(void)
{DMA_InitTypeDef DMA_InitStructure;RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1 , ENABLE); //DMA1时钟使能DMA_DeInit(DMA1_Stream6);while (DMA_GetCmdStatus(DMA1_Stream6) !&＃61; DISABLE); //等待DMA可配置DMA_InitStructure.DMA_Channel &＃61; DMA_Channel_4; //DMA通道配置DMA_InitStructure.DMA_PeripheralBaseAddr &＃61; (uint32_t)&USART2->DR; //DMA外设地址DMA_InitStructure.DMA_Memory0BaseAddr &＃61; (uint32_t)USART2_DMA_TX_Buffer; //发送缓存指针DMA_InitStructure.DMA_DIR &＃61; DMA_DIR_MemoryToPeripheral; //DMA传输方向&＃xff1a;内存--->外设DMA_InitStructure.DMA_BufferSize &＃61; USART2_DMA_TX_BUFFER_MAX_LENGTH; //数据传输字节数量DMA_InitStructure.DMA_PeripheralInc &＃61; DMA_PeripheralInc_Disable; //外设非增量模式DMA_InitStructure.DMA_MemoryInc &＃61; DMA_MemoryInc_Enable; //存储器增量模式DMA_InitStructure.DMA_PeripheralDataSize &＃61; DMA_PeripheralDataSize_Byte; //外设数据长度:8位DMA_InitStructure.DMA_MemoryDataSize &＃61; DMA_MemoryDataSize_Byte; //存储器数据长度:8位 DMA_InitStructure.DMA_Mode &＃61; DMA_Mode_Normal; //使用普通模式 DMA_InitStructure.DMA_Priority &＃61; DMA_Priority_Medium; //中等优先级 DMA_Priority_HighDMA_InitStructure.DMA_FIFOMode &＃61; DMA_FIFOMode_Disable; DMA_InitStructure.DMA_FIFOThreshold &＃61; DMA_FIFOThreshold_Full;DMA_InitStructure.DMA_MemoryBurst &＃61; DMA_MemoryBurst_Single; //存储器突发单次传输DMA_InitStructure.DMA_PeripheralBurst &＃61; DMA_PeripheralBurst_Single; //外设突发单次传输DMA_Init(DMA1_Stream6, &DMA_InitStructure); //初始化DMA StreamDMA_Cmd(DMA1_Stream6, DISABLE); //开启DMA传输
}

2、USART2  RX DMA初始化程序

void USART2_DMA_Rx_Configuration(void)
{DMA_InitTypeDef DMA_InitStructure;RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1 , ENABLE); //DMA1时钟使能DMA_DeInit(DMA1_Stream5);while (DMA_GetCmdStatus(DMA1_Stream5) !&＃61; DISABLE); //等待DMA可配置 DMA_InitStructure.DMA_Channel &＃61; DMA_Channel_4; //通道选择DMA_InitStructure.DMA_PeripheralBaseAddr &＃61; (uint32_t)&USART2->DR; //DMA外设地址DMA_InitStructure.DMA_Memory0BaseAddr &＃61; (uint32_t)USART2_DMA_RX_Buffer; //接收缓存指针DMA_InitStructure.DMA_DIR &＃61; DMA_DIR_PeripheralToMemory ; //DMA传输方向&＃xff1a;外设到存储器模式&＃xff1a;外设--->内存DMA_InitStructure.DMA_BufferSize &＃61; USART2_DMA_RX_BUFFER_MAX_LENGTH; //缓冲大小 DMA_InitStructure.DMA_PeripheralInc &＃61; DMA_PeripheralInc_Disable; //外设非增量模式DMA_InitStructure.DMA_MemoryInc &＃61; DMA_MemoryInc_Enable; //存储器增量模式DMA_InitStructure.DMA_PeripheralDataSize &＃61; DMA_PeripheralDataSize_Byte; //外设数据长度:8位DMA_InitStructure.DMA_MemoryDataSize &＃61; DMA_MemoryDataSize_Byte; //存储器数据长度:8位DMA_InitStructure.DMA_Mode &＃61; DMA_Mode_Normal; //使用普通模式 DMA_InitStructure.DMA_Priority &＃61; DMA_Priority_Medium; //中等优先级 DMA_Priority_VeryHighDMA_InitStructure.DMA_FIFOMode &＃61; DMA_FIFOMode_Disable; DMA_InitStructure.DMA_FIFOThreshold &＃61; DMA_FIFOThreshold_Full;DMA_InitStructure.DMA_MemoryBurst &＃61; DMA_MemoryBurst_Single; //存储器突发单次传输DMA_InitStructure.DMA_PeripheralBurst &＃61; DMA_PeripheralBurst_Single; //外设突发单次传输DMA_Init(DMA1_Stream5 , &DMA_InitStructure); //初始化DMA_Stream DMA_Cmd(DMA1_Stream5, ENABLE); //开启DMA传输
}

 3、USART2  启动DMA发送初始化程序


void USART2_DMA_Begin_Send(uint8_t *send_buffer , uint16_t nSendCount)
{ if (nSendCount }


4、USART2  DMA方式端口初始化程序&＃xff08;包含DMA配置&＃xff09;


void USART2_Configuration(void)
{GPIO_InitTypeDef GPIO_InitStructure;USART_InitTypeDef USART_InitStructure;RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2 , ENABLE); //for USART2, USART3, UART4 or UART5. RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2);GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2); GPIO_InitStructure.GPIO_Mode &＃61; GPIO_Mode_AF;GPIO_InitStructure.GPIO_OType &＃61; GPIO_OType_PP;GPIO_InitStructure.GPIO_PuPd &＃61; GPIO_PuPd_UP;GPIO_InitStructure.GPIO_Pin &＃61; GPIO_Pin_2;GPIO_InitStructure.GPIO_Speed &＃61; GPIO_Speed_50MHz;GPIO_Init(GPIOA, &GPIO_InitStructure);GPIO_InitStructure.GPIO_Mode &＃61; GPIO_Mode_AF;GPIO_InitStructure.GPIO_Pin &＃61; GPIO_Pin_3;GPIO_Init(GPIOA, &GPIO_InitStructure);USART_InitStructure.USART_BaudRate &＃61; 115200;USART_InitStructure.USART_WordLength &＃61; USART_WordLength_8b;USART_InitStructure.USART_StopBits &＃61; USART_StopBits_1;USART_InitStructure.USART_Parity &＃61; USART_Parity_No ;USART_InitStructure.USART_HardwareFlowControl &＃61; USART_HardwareFlowControl_None;USART_InitStructure.USART_Mode &＃61; USART_Mode_Rx | USART_Mode_Tx;USART_Init(USART2, &USART_InitStructure);USART_Cmd(USART2, ENABLE);USART_ClearFlag(USART2, USART_FLAG_TC); //清除发送完成标志 while (USART_GetFlagStatus(USART2, USART_FLAG_TC) &＃61;&＃61; RESET); //等待空闲帧发送完成后再清零发送完成标志&＃xff08;警告&＃xff1a;如果不使能USART_Mode_Tx&＃xff0c;会导致单片机在这里死机&＃xff09;USART_ClearFlag(USART2, USART_FLAG_TC); //清除发送完成标志USART_ITConfig(USART2, USART_IT_RXNE, DISABLE); //禁止USART1接收不为空中断USART_ITConfig(USART2, USART_IT_TXE, DISABLE); //禁止USART1发送空中断USART_ITConfig(USART2, USART_IT_IDLE, ENABLE); //开启USART1空闲中断 USART_ITConfig(USART2, USART_IT_TC, ENABLE); //开启USART1传输完成中断 USART_DMACmd(USART2 , USART_DMAReq_Tx,ENABLE); //使能串口的DMA发送USART_DMACmd(USART2 , USART_DMAReq_Rx,ENABLE); //使能串口的DMA接收}

5、USART2   DMA中断接收和DMA中断发送

void USART2_IRQHandler(void)
{int16_t ch;if (USART_GetITStatus(USART2,USART_IT_IDLE) !&＃61; RESET){ USART_ClearITPendingBit(USART2 , USART_IT_IDLE); //必须先清除总线空闲中断标识&＃xff0c;然后读一下数据寄存器&＃xff0c;DMA接收才会正确&＃xff08;先读SR&＃xff0c;然后读DR才能清除空闲中断标识&＃xff09;注意&＃xff1a;这句必须要&＃xff0c;否则不能够清除中断标志位。ch &＃61; USART_ReceiveData(USART2); //必须先清除总线空闲中断标识&＃xff0c;然后读一下数据寄存器&＃xff0c;DMA接收才会正确&＃xff08;先读SR&＃xff0c;然后读DR才能清除空闲中断标识&＃xff09;注意&＃xff1a;这句必须要&＃xff0c;否则不能够清除中断标志位。#ifdef __DEBUG_stm32f407____DEBUG_USART2_IT_IDLE&＃43;&＃43;;#endifDMA_Cmd(DMA1_Stream5 , DISABLE); //关闭DMA,防止处理其间有数据DMA_ClearFlag(DMA1_Stream5 , DMA_FLAG_TCIF5 | DMA_FLAG_FEIF5 | DMA_FLAG_DMEIF5 | DMA_FLAG_TEIF5 | DMA_FLAG_HTIF5);//清零标志位ch &＃61; USART2_DMA_RX_BUFFER_MAX_LENGTH - DMA_GetCurrDataCounter(DMA1_Stream5);if (ch > 0){//if (MB_USART2.MBHosts_Query_isr &＃61;&＃61; enum_MODBUS_STATUS_SEND_OVER){MB_USART2.Outtime_mark &＃61; TRUE;MB_USART2.receCount &＃61; ch;memcpy(MB_USART2.mscomm_buffer , USART2_DMA_RX_Buffer , MB_USART2.receCount);}}DMA_SetCurrDataCounter(DMA1_Stream5 , USART2_DMA_RX_BUFFER_MAX_LENGTH);DMA_Cmd(DMA1_Stream5, ENABLE);}else if (USART_GetITStatus(USART2,USART_IT_TC)!&＃61; RESET) {USART_ClearITPendingBit(USART2, USART_IT_TC);#ifdef __DEBUG_stm32f407____DEBUG_USART2_IT_TC&＃43;&＃43;;#endifDMA_ClearFlag(DMA1_Stream6 , DMA_FLAG_TCIF6 | DMA_FLAG_FEIF6 | DMA_FLAG_DMEIF6 | DMA_FLAG_TEIF6 | DMA_FLAG_HTIF6);DMA_SetCurrDataCounter(DMA1_Stream6 , 0); //清除数据长度if (MB_USART2.MBHosts_Query_isr &＃61;&＃61; enum_MODBUS_STATUS_SEND_BEGINING){MB_USART2.MBHosts_Query_isr &＃61; enum_MODBUS_STATUS_SEND_OVER; TIM_Cmd(TIM1, DISABLE);TIM_SetCounter(TIM1, 0x00);TIM_Cmd(TIM1, ENABLE);} GPIO_USART2_RS485_RECIVE_enable();}}

6、主程序

void main(void)
{USART2_Configuration();USART2_DMA_Tx_Configuration();USART2_DMA_Rx_Configuration();while (1){//在合适的时候调用USART2_DMA_Begin_Send(uint8_t *send_buffer , uint16_t nSendBytes)// 通过DMA中断方式将数据发送出去}
}

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