求出f407ve uart4外接485无法通信的问题

qishuhua · 发表于 2022-7-8 16:23:16

#define RS485_TX_EN PAout(5) //485模式控制.0,接收;1,发送.

void UART4_IRQHandler(void)
{
u8 res;
u8 i;
if(USART_GetITStatus(UART4, USART_IT_RXNE) != RESET)
{
   res =USART_ReceiveData(UART4);
if(RS485_RX_CNT<8)
{
RS485_RX_BUF[RS485_RX_CNT]=res;
RS485_RX_CNT++;
}
else
{
RS485_TX_EN=1;
for(i=0;i<8;i++)
{
while(USART_GetFlagStatus(UART4,USART_FLAG_TC)==RESET);
USART_SendData(UART4,RS485_RX_BUF);
}
RS485_RX_CNT=0;
RS485_TX_EN=0;
}
}
}

//初始化IO 串口2
//bound:波特率
void RS485_Init(u32 bound)
{

  GPIO_InitTypeDef GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;

RCC_APB1PeriphClockCmd(RCC_AHB1Periph_GPIOA,ENABLE); //使能GPIOA时钟
RCC_AHB1PeriphClockCmd(RCC_APB1Periph_UART4,ENABLE); //使能UART4时钟

//串口0，1引脚复用映射
GPIO_PinAFConfig(GPIOA,GPIO_PinSource0,GPIO_AF_UART4); //GPIOA2复用为UART4
GPIO_PinAFConfig(GPIOA,GPIO_PinSource1,GPIO_AF_UART4); //GPIOA3复用为UART4

//USART4
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_Init(GPIOA,&GPIO_InitStructure);

//485模式控制
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd =GPIO_PuPd_DOWN;
GPIO_Init(GPIOA,&GPIO_InitStructure);

//UART4 初始化设置
USART_InitStructure.USART_BaudRate = bound;//波特率设置
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;
USART_Init(UART4, &USART_InitStructure);

USART_Cmd(UART4, ENABLE);

USART_ClearFlag(UART4, USART_FLAG_TC);

USART_ITConfig(UART4, USART_IT_RXNE, ENABLE);//开启接受中断

//UART4 NVIC 配置
NVIC_InitStructure.NVIC_IRQChannel = UART4_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=3;//抢占优先级3
NVIC_InitStructure.NVIC_IRQChannelSubPriority =3; //子优先级3
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、

RS485_TX_EN=0; //默认为接收模式
}