开通UART，PA1和PA8作为普通IO口应该如何配置？

autoav · 发表于 2018-8-31 10:07:52

void uart2_init(u32 bound)
{
//GPIO端口设置
GPIO_InitTypeDef GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
DMA_InitTypeDef DMA_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE); //使能GPIOA时钟
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE); //使能USART2时钟
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE); //使能DMA传输

USART_DeInit(USART2);  //复位串口2

//485控制脚，低电平接收，高电平发送 PA1
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1; //PA.1
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //复用推挽输出
GPIO_Init(GPIOA, &GPIO_InitStructure); //初始化PA1
   GPIO_SetBits(GPIOA, GPIO_Pin_1);//就是这一行，PA1无法输出高电平，UART2的PA8也是一样，无法输出高电平
PAout(1) = 0;

//USART2_TX PA2
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2; //PA.2
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //复用推挽输出
GPIO_Init(GPIOA, &GPIO_InitStructure); //初始化PA2

//USART2_RX    PA3
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;//浮空输入
GPIO_Init(GPIOA, &GPIO_InitStructure);  //初始化PA3

//Usart2 NVIC 配置
NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 3 ; //抢占优先级3
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;       //子优先级2
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;          //IRQ通道使能
NVIC_Init(&NVIC_InitStructure); //根据指定的参数初始化VIC寄存器

//USART 初始化设置
USART_InitStructure.USART_BaudRate = bound;//一般设置为9600;
USART_InitStructure.USART_WordLength = USART_WordLength_8b;//字长为8位数据格式
USART_InitStructure.USART_StopBits = USART_StopBits_1;//一个停止位
USART_InitStructure.USART_Parity = USART_Parity_No;//无奇偶校验位
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//无硬件数据流控制
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx; //收发模式

USART_Init(USART2, &USART_InitStructure); //初始化串口
USART_ITConfig(USART2, USART_IT_IDLE, ENABLE);//开启空闲中断
USART_DMACmd(USART2, USART_DMAReq_Rx, ENABLE); //使能串口2 DMA接收
USART_Cmd(USART2, ENABLE);                   //使能串口
Cmd.RxReq = 0;

//USART2_RX相应的DMA配置
DMA_DeInit(DMA1_Channel6); //将DMA的通道6寄存器重设为缺省值  串口2_RX对应的是DMA通道6
DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)&USART2->DR;  //DMA外设ADC基地址
DMA_InitStructure.DMA_MemoryBaseAddr = (u32)DMA_U2_RxBuf;  //DMA内存基地址
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;  //数据传输方向，从外设读取发送到内存
DMA_InitStructure.DMA_BufferSize = DMA_U2_RxLen;  //DMA通道的DMA缓存的大小
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;  //外设地址寄存器不变
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;  //内存地址寄存器递增
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;  //数据宽度为8位
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte; //数据宽度为8位
DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;  //工作在正常缓存模式
DMA_InitStructure.DMA_Priority = DMA_Priority_Medium; //DMA通道 x拥有中优先级
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;  //DMA通道x没有设置为内存到内存传输
DMA_Init(DMA1_Channel6, &DMA_InitStructure);  //根据DMA_InitStruct中指定的参数初始化DMA的通道USART2_Rx_DMA_Channel所标识的寄存器

DMA_Cmd(DMA1_Channel6, ENABLE);  //正式驱动DMA传输
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