先來介紹一下UART空閑中斷。UART常用的接收中斷響應有：接收數據 就緒可讀中斷RXNE（這是最常用的）、數據溢出中斷（ORE）、奇偶校驗錯中斷（PE）和空閑中斷（IDLE）。空閑中斷是指當總線檢測到一幀發完后， 總線空閑則會將此位置一，如果USART_CR1中的IDLEIE為’1’，則產生中斷。空閑中斷有兩個比較有意思的特點：
1、清零方式：軟件清零，先讀USART_SR，然后讀USART_DR
2、直到RXNE被置一后IDLE才能被重讀置一，即IDLE被置一并軟件清零后，只有之后再次接收到數據，IDLE才能被置一。這樣就防止了總線長時間空閑而多次引發空閑中斷。
好的廢話不多說上例程。
以下都是通過DMA接收GPS串口的子模塊程序
#define UART_RX_LEN 128
static char Uart_Rx[UART_RX_LEN];//GPS接收數據
void GPS_Init(void)
{
RCC_Configuration();//時鐘打開
GPIO_Configuration();//GPIO配置
DMA_Configuration();//DMA配置
UART_Configuration();//UART配置
NVIC_Configuration();//中斷優先級配置
}
void RCC_Configuration(void)
{
//打開串口對應的外設時鐘
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);
//啟動DMA時鐘
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);
}
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_Init(GPIOA, &GPIO_InitStructure);
}
void DMA_Configuration(void)
{
DMA_InitTypeDef DMA_InitStructure;
//DMA1通道5配置
DMA_DeInit(DMA1_Channel5);
//外設地址
DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)(&USART1->DR);
//內存地址
DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)Uart_Rx;
//dma傳輸方向單向
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
//設置DMA在傳輸時緩沖區的長度
DMA_InitStructure.DMA_BufferSize = UART_RX_LEN;
//設置DMA的外設遞增模式，一個外設
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
//設置DMA的內存遞增模式
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
//外設數據字長
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
//內存數據字長
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
//設置DMA的傳輸模式
DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
//設置DMA的優先級別
DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh;
//設置DMA的2個memory中的變量互相訪問
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
DMA_Init(DMA1_Channel5,&DMA_InitStructure);
//使能通道5
DMA_Cmd(DMA1_Channel5,ENABLE);
}
void UART_Configuration(void)
{
USART_InitTypeDef USART_InitStructure;
//初始化參數
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_InitStructure.USART_BaudRate = 9600;
//初始化串口
USART_Init(USART1,&USART_InitStructure);
//中斷配置
USART_ITConfig(USART1,USART_IT_TC,DISABLE);
USART_ITConfig(USART1,USART_IT_RXNE,DISABLE);
USART_ITConfig(USART1,USART_IT_IDLE,ENABLE);
//采用DMA方式接收
USART_DMACmd(USART1,USART_DMAReq_Rx,ENABLE);
}
void NVIC_Configuration(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
//配置UART1中斷
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_3);
NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn; //通道設置為串口1中斷
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2; //中斷占先等級0
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1; //中斷響應優先級0
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //打開中斷
NVIC_Init(&NVIC_InitStructure);
}
void USART1_IRQHandler(void)
{
uint32_t Length = 0;//數據長度
if(USART_GetITStatus(USART1, USART_IT_IDLE) != RESET)
{
DMA_Cmd(DMA1_Channel5,DISABLE);
Length = USART1->SR;
Length = USART1->DR; //清USART_IT_IDLE標志
Length = UART_RX_LEN - DMA_GetCurrDataCounter(DMA1_Channel5);
//設置傳輸數據長度
DMA1_Channel5->CNDTR = UART_RX_LEN;//重裝填,并讓接收地址偏址從0開始
DMA_Cmd(DMA1_Channel5, ENABLE);//處理完,重開DMA
}
__nop();
}
void GPS_Cmd(FunctionalState NewState)
{
USART_Cmd(USART1, NewState);
}
以下是調用函數，一般在main函數中
GPS_Init();
GPS_Cmd(ENABLE);
此程序經過博主親測，有效可用。
