目标环境：
MCU：stm32f103C8T6
stm32 library：standard library V3.5.0
RTOS：FreeRTOS
实现功能：
a. 接收DMA和串口IDLE中断配合接收不定长数据
b. 使用DMA发送数据
一. 初始化
#include "stm32f10x.h"
#include "stm32f10x_rcc.h"
#include "stm32f10x_usart.h"
#include "stm32f10x_gpio.h"
#include "stm32f10x_dma.h"
#include "freertos.h"
#include "semphr.h"
#define UART_RECV_BUF_SIZE (128) /*DMA接收缓存大小*/
#define UART_SEND_BUF_SIZE (128) /*DMA发送缓存大小*/
#define USART2_RX_IDLE_PRIORITY (0x0b) /*串口IDLE中断优先级*/
#define USART2_DMA_TX_PRIORITY (0x0c) /*DMA发送中断优先级*/
static u8 s_Uart_2_Recv_Buf[UART_RECV_BUF_SIZE] = {0}; /*存储DMA接收的数据*/
static u8 s_Uart_2_Send_Buf[UART_SEND_BUF_SIZE] = {0}; /*DMA发送缓存*/
static SemaphoreHandle_t s_Uart_2_Send_Lock; /*串口使用Lock，保证通过串口发送的数据完整性*/
static QueueHandle_t s_Uart_Recv_Queue; /*与任务通信的消息队列*/
/*****************************************************************************
**函 数 名: __Uart_Send_Lock_Init
**输入参数: void
**输出参数: 无
**返 回 值: 无
**功能描述: 初始化锁和消息队列
**作 者: sdc
*****************************************************************************/
static void __Uart_Send_Lock_Init(void)
{
s_Uart_2_Send_Lock = xSemaphoreCreateBinary();
if(NULL == s_Uart_2_Send_Lock)
{
printf("lock create fail\n");
}
xSemaphoreGive(s_Uart_2_Send_Lock); /*保证第一次能够发送成功*/
s_Uart_Recv_Queue = xQueueCreate(10, sizeof(UART_DATA *)); /*消息队列，与任务实现通信*/
}
/*****************************************************************************
**函 数 名: __Uart_2_Init
**输入参数: u32 baudrate:波特率
**输出参数: 无
**返 回 值: 无
**功能描述: 初始化串口2和DMA
**作 者: sdc
*****************************************************************************/
static void __Uart_2_Init(u32 baudrate)
{
GPIO_InitTypeDef GPIO_InitStruct;
USART_InitTypeDef USART_InitStruct;
DMA_InitTypeDef DMA_InitStruct;
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);
/*初始化使用USART2使用的引脚, PA2为复用推挽输出,PA3为浮空输入*/
GPIO_InitStruct.GPIO_Pin = GPIO_Pin_2;
GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStruct);
GPIO_InitStruct.GPIO_Pin = GPIO_Pin_3;
GPIO_InitStruct.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA, &GPIO_InitStruct);
USART_DeInit(USART2);
USART_InitStruct.USART_BaudRate = baudrate;
USART_InitStruct.USART_WordLength = USART_WordLength_8b;
USART_InitStruct.USART_Parity = USART_Parity_No;
USART_InitStruct.USART_StopBits = USART_StopBits_1;
USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
USART_InitStruct.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
USART_Init(USART2, &USART_InitStruct);
NVIC_SetPriority(USART2_IRQn, USART2_RX_IDLE_PRIORITY);
USART_ITConfig(USART2, USART_IT_IDLE, ENABLE);
NVIC_EnableIRQ(USART2_IRQn);
DMA_DeInit(DMA1_Channel7);
DMA_InitStruct.DMA_PeripheralBaseAddr = (u32)(&(USART2->DR));
DMA_InitStruct.DMA_DIR = DMA_DIR_PeripheralDST;
DMA_InitStruct.DMA_BufferSize = 1;
DMA_InitStruct.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStruct.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStruct.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStruct.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
DMA_InitStruct.DMA_Mode = DMA_Mode_Normal;
DMA_InitStruct.DMA_Priority = DMA_Priority_VeryHigh;
DMA_InitStruct.DMA_M2M = DMA_M2M_Disable;
DMA_Init(DMA1_Channel7, &DMA_InitStruct);
/*使能DMA发送中断*/
NVIC_SetPriority(DMA1_Channel7_IRQn, USART2_DMA_TX_PRIORITY);
NVIC_EnableIRQ(DMA1_Channel7_IRQn);
DMA_ITConfig(DMA1_Channel7, DMA_IT_TC, ENABLE);
USART_DMACmd(USART2, USART_DMAReq_Tx, ENABLE);
/*USART2 recv DMA config*/
DMA_DeInit(DMA1_Channel6);
DMA_InitStruct.DMA_PeripheralBaseAddr = (u32)(&(USART2->DR));
DMA_InitStruct.DMA_MemoryBaseAddr = (u32)s_Uart_2_Recv_Buf;
DMA_InitStruct.DMA_DIR = DMA_DIR_PeripheralSRC;
DMA_InitStruct.DMA_BufferSize = UART_RECV_BUF_SIZE;
DMA_InitStruct.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStruct.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStruct.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStruct.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
DMA_InitStruct.DMA_Mode = DMA_Mode_Normal;
DMA_InitStruct.DMA_Priority = DMA_Priority_VeryHigh;
DMA_InitStruct.DMA_M2M = DMA_M2M_Disable;
DMA_Init(DMA1_Channel6, &DMA_InitStruct);
DMA_Cmd(DMA1_Channel6, ENABLE);
USART_DMACmd(USART2, USART_DMAReq_Rx, ENABLE);
USART_Cmd(USART2, ENABLE);
}二. 串口发送
/*****************************************************************************
**函 数 名: Uart_Send
**输入参数: u8 *buff:数据缓存
u32 len:数据长度
**输出参数: 无
**返 回 值:
**功能描述: 使用串口发送数据
**作 者: sdc
*****************************************************************************/
void Uart_Send(u8 *buff, u32 len)
{
xSemaphoreTake(s_Uart_2_Send_Lock, portMAX_DELAY);
memcpy(s_Uart_2_Send_Buf, buff, len);
DMA_Cmd(DMA1_Channel7, DISABLE);
DMA1_Channel7->CMAR = (u32)s_Uart_2_Send_Buf;
DMA_SetCurrDataCounter(DMA1_Channel7, len);
DMA_Cmd(DMA1_Channel7, ENABLE);
}三. DMA中断和串口中断处理
void DMAChannel7_IRQHandler(void)
{
if(DMA_GetITStatus(DMA1_IT_TC7))
{
DMA_ClearITPendingBit(DMA1_IT_TC7);
xSemaphoreGiveFromISR(s_Uart_2_Send_Lock, &xHigherPriorityTaskWoken);
if(pdFALSE != xHigherPriorityTaskWoken)
{
/*can force a contex switch*/
}
}
}
void USART2_IRQHandler(void)
{
if(RESET != USART_GetITStatus(USART2, USART_IT_IDLE))
{
USART_ReceiveData(USART2);//读取数据注意：这句必须要，否则不能够清除中断标志位。
USART_ClearITPendingBit(USART2,USART_IT_IDLE);
DMA_Cmd(DMA1_Channel6, DISABLE);
data_len = UART_RECV_BUF_SIZE - DMA_GetCurrDataCounter(DMA1_Channel6);
DMA_SetCurrDataCounter(DMA1_Channel6, UART_RECV_BUF_SIZE);
data = pvPortMalloc(data_len + sizeof(UART_DATA));
if(NULL != data)
{
data->sender = uart_index;
data->size = data_len;
memcpy(data->recv_buf, dma_recv_buff, data_len);
if(pdPASS != xQueueSendFromISR(s_Uart_Recv_Queue, &data, NULL))
{
/*注意错误情况的处理*/
}
}
DMA_Cmd(DMA1_Channel6, ENABLE);
}
}其他：
如果需要使用3个串口，并且都使用DMA发送和接收，初始化和中断处理函数的重复性太大，应将相同的部分提取出来组成新的函数，以传参的方式进行处理。目前没想到很好的处理方法。