【原创】STM32F103的USART2配置代码， DMA方式发送！

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wjandsq 发布时间：2015-6-25 14:07

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STM32电机培训online，大佬带你玩电机#include "stm32f10x.h"#include "stm32f10x_usart.h"#include "stm32f10x_dma.h"uint8_t HEX_CODE[16] = {'0','1','2','3','4','5','6','7','8','9','A','B','C','D','E','F'};uint8_t USART2_DMA_TX_Buf[1024];uint8_t Flag_USART2_DMA_TX_Finished = 1;uint8_t Flag_USART2_Send = 0;/** * Function Name : USART2_Config * Description : None * Input : None * Output : None * Return : None */void USART2_Config(void) { GPIO_InitTypeDef GPIO_InitStructure; USART_InitTypeDef USART_InitStructure; DMA_InitTypeDef DMA_InitStructure; NVIC_InitTypeDef NVIC_InitStructure; /* config USART2 clock */ RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE); RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE); /* *********************USART2 GPIO config **********************/ /* Configure USART1 Tx (PA.02) as alternate function push-pull */ GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(GPIOA, &GPIO_InitStructure); /* Configure USART2 Rx (PA.03) as input floating */ GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING; GPIO_Init(GPIOA, &GPIO_InitStructure); /* USART2 mode config 115200 8-N-1*/ USART_InitStructure.USART_BaudRate = 115200; USART_InitStructure.USART_WordLength = USART_WordLength_8b; USART_InitStructure.USART_StopBits = USART_StopBits_1; USART_InitStructure.USART_Parity = USART_Parity_No ; USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None; USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx; USART_Init(USART2, &USART_InitStructure); USART_Cmd(USART2, ENABLE); USART_DMACmd(USART2, USART_DMAReq_Tx, ENABLE); /* Enable USART2 DMA TX request */ RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE); DMA_DeInit(DMA1_Channel7); DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)(&USART2->DR); DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)USART2_DMA_TX_Buf; DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST; DMA_InitStructure.DMA_BufferSize = 0; DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable; DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte; DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte; DMA_InitStructure.DMA_Mode = DMA_Mode_Normal; DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh; DMA_InitStructure.DMA_M2M = DMA_M2M_Disable; DMA_Init(DMA1_Channel7, &DMA_InitStructure); DMA_ITConfig(DMA1_Channel7, DMA_IT_TC, ENABLE); NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1); /* Enable USART2 DMA TX Finish Interrupt */ NVIC_InitStructure.NVIC_IRQChannel = DMA1_Channel7_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure); /* Enable USART2 Interrupt */ NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; NVIC_Init(&NVIC_InitStructure);}/** * Function Name : USART2_Data_Load * Description : None * Input : None * Output : None * Return : None */void USART2_Data_Load(uint16_t temp1, uint16_t temp2, uint8_t temp3){ USART2_DMA_TX_Buf[0] = HEX_CODE[temp1 >> 4]; USART2_DMA_TX_Buf[1] = HEX_CODE[temp1 & 0x0F]; USART2_DMA_TX_Buf[2] = HEX_CODE[temp2 >> 4]; USART2_DMA_TX_Buf[3] = HEX_CODE[temp2 & 0x0F]; USART2_DMA_TX_Buf[4] = 0x20; USART2_DMA_TX_Buf[5] = HEX_CODE[temp3]; USART2_DMA_TX_Buf[6] = 0x0D; USART2_DMA_TX_Buf[7] = 0x0A; Flag_USART2_Send = 1;}/** * Function Name : USART2_Data_Send * Description : None * Input : None * Output : None * Return : None */void USART2_Data_Send(uint16_t len) { if(Flag_USART2_Send){ if(Flag_USART2_DMA_TX_Finished == 1){ Flag_USART2_DMA_TX_Finished = 0; DMA1_Channel7->CMAR = (uint32_t)&USART2_DMA_TX_Buf[0]; DMA1_Channel7->CNDTR = 8; // len DMA_Cmd(DMA1_Channel7, ENABLE); Flag_USART2_Send = 0; } }}/** * Function Name : USART2_IRQHandler * Description : This function handles USART2 global interrupt request. * Input : None * Output : None * Return : None */void USART2_IRQHandler(void) { if(USART_GetITStatus(USART2,USART_IT_RXNE) != RESET) { (void)USART_ReceiveData(USART2); } if (USART_GetITStatus(USART2, USART_IT_TC) != RESET) { /* Disable the USART2 Transmit Complete interrupt */ USART_ITConfig(USART2, USART_IT_TC, DISABLE); Flag_USART2_DMA_TX_Finished = 1; } /* If overrun condition occurs, clear the ORE flag a.nd recover communication */ if(USART_GetFlagStatus(USART2,USART_FLAG_ORE) != RESET) { (void)USART_ReceiveData(USART2); }}/** * Function Name : DMA1_Channel7_IRQHandler * Description : This function handles DMA1 Channel 7 interrupt request. * Input : None * Output : None * Return : None */void DMA1_Channel7_IRQHandler(void){ if(DMA_GetITStatus(DMA1_IT_TC7)) { /* USART2 DMA 传输完成 */ DMA_ClearITPendingBit(DMA1_IT_TC7); DMA_Cmd(DMA1_Channel7, DISABLE); /* Enable USART2 Transmit complete interrupt */ USART_ITConfig(USART2, USART_IT_TC, ENABLE); }}

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沐紫回答时间：2015-6-25 14:25:56

谢谢，要是有代码注释或者文字说明更好啦

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wyxy163@126.com 回答时间：2015-6-25 17:05:13

提示: 作者被禁止或删除内容自动屏蔽

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wjandsq 回答时间：2015-6-25 20:37:02

本帖最后由 wjandsq 于 2015-6-25 20:45 编辑 所谓STM32F103串口数据的DMA发送，其本质流程如下：1. 要发送的数据放在USART2_DMA_TX_Buf缓冲。2. STM32串口DMA发送和DSP相比的优势。启动DMA传输后，USART2_DMA_TX_Buf缓冲中的数据通过DMA1_Channel7通道，自动传输到USART2->DR寄存器，这个工作不需要CPU干预，可以极大的节省CPU的资源。和DSP的FIFO相比，这优势很大，因为DSP的FIFO只有16字节，这意味着DSP的串口通过 FIFO发送数据时，如果FIFO缓冲为空，可以迅速填入16个字节，然后去处理其它的事务。而STM32的DMA发送则没有此种限制。更具体的说，如果DSP发送的数据超过16字节，则必须等待前16个字节数据发送完毕，然后再继续发送后续的数据，需要第二次甚至第N次处理。而STM32启动一次DMA就搞定(DMA最大传输65535个数据)。3. 发送结束的一些事务处理 DMA传输完毕，数据全部通过DMA1_Channel7通道依次传入USART2-DR，这里开启了 DMA传输完毕中断，进这个中断时，USART2-DR寄存器是最后一个要发送的数据，此时打开USART2发送完毕中断，进入USART2发送完毕中断后，可以设定标识，也可以操作GPIO, 进行RS485的换向动作。最新的STM32F103的HAL库，几乎所有的通信，都可以启用DMA，HAL库函数抽象层次过高，灵活性不够，但比较适合使用操作系统的场合。可以把HAL库的宏定义拷贝过来使用，以提高标准外设驱动库的效率，又保证标准外设驱动库的灵活性。