根据原子STM32F407的USART1修改成STM32F429的UART5无法实现通讯，还请指点以下初始化是否有错！

碧海航歆 · 发表于 2015-8-20 00:41:01

void uart5_init(u32 pclk2,u32 bound)
{

float temp;
u16 mantissa;
u16 fraction;
temp=(float)(pclk2*1000000)/(bound*16);//????USARTDIV@OVER8=0
mantissa=temp; //??????????·?
fraction=(temp-mantissa)*16; //??????????·?@OVER8=0
mantissa<<=4;
mantissa+=fraction;
RCC->AHB1ENR|=(1<<2)|(1<<3); //????PORTC\PORTD???±??
RCC->AHB1ENR|=1<<20; //?????®??UART5?±??
// GPIO_Set(GPIOB,PIN6|PIN7,GPIO_MODE_AF,GPIO_OTYPE_PP,GPIO_SPEED_50M,GPIO_PUPD_PU);//PA9,PA10,????????,????????
GPIO_Set(GPIOC,PIN12,GPIO_MODE_AF,GPIO_OTYPE_PP,GPIO_SPEED_50M,GPIO_PUPD_PU);//PC12????????,????????
GPIO_Set(GPIOD,PIN2,GPIO_MODE_AF,GPIO_OTYPE_PP,GPIO_SPEED_50M,GPIO_PUPD_PU); //PD2????????,????????

GPIO_AF_Set(GPIOC,12,8); //PC12
GPIO_AF_Set(GPIOD,2,8); //PD2
//?¨?????è??
UART5->BRR=mantissa; //?¨?????è??
UART5->CR1&=~(1<<15); //?è??OVER8=0
UART5->CR1|=1<<3; //?®??·???????
#if EN_UART5_RX //??????????????
//????????????
UART5->CR1|=1<<2; //?®??????????
UART5->CR1|=1<<5; //??????????·???????????
MY_NVIC_Init(3,3,UART5_IRQn,2);//×é2??×?????????
#endif
UART5->CR1|=1<<13; //?®??????
}
//===============================================
void Uart5_putch(u8 k)
{
if(k == '\n')
{
//????·?????×???????UART2??·?????????
UART5->DR = k;
//????·????ê??
while (!(UART5->SR & USART_FLAG_TXE));
}
else
{
UART5->DR = k;
while (!(UART5->SR & USART_FLAG_TXE));
}
}

USART1已经能够正常使用，只是UART5找不到是哪里出问题了！还请原子指点

碧海航歆 · 发表于 2015-8-20 00:41:02

回复【2楼】正点原子:
---------------------------------
该问题已经解决了，还是谢谢原子哥帮顶，附上初始化代码
void uart5(int baud)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    USART_InitTypeDef USART_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB|RCC_AHB1Periph_GPIOC|RCC_AHB1Periph_GPIOD,ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_UART5,ENABLE);


    GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_OType=GPIO_OType_OD;
    GPIO_InitStructure.GPIO_Speed=GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_PuPd=GPIO_PuPd_NOPULL;
    GPIO_InitStructure.GPIO_Pin=GPIO_Pin_12;
    GPIO_Init(GPIOC,&GPIO_InitStructure);

    GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_PuPd=GPIO_PuPd_UP;
    GPIO_InitStructure.GPIO_Pin=GPIO_Pin_2;
    GPIO_Init(GPIOD,&GPIO_InitStructure);

    GPIO_PinAFConfig(GPIOC,GPIO_PinSource12,GPIO_AF_UART5);
    GPIO_PinAFConfig(GPIOD,GPIO_PinSource2,GPIO_AF_UART5);

    USART_DeInit(UART5);

    USART_InitStructure.USART_BaudRate=baud;
    USART_InitStructure.USART_Mode=USART_Mode_Rx|USART_Mode_Tx;
    USART_InitStructure.USART_WordLength=USART_WordLength_8b;
    USART_InitStructure.USART_Parity=USART_Parity_No;
    USART_InitStructure.USART_StopBits=USART_StopBits_1;
    USART_InitStructure.USART_HardwareFlowControl=USART_HardwareFlowControl_None;
    USART_Init(UART5,&USART_InitStructure);

     NVIC_InitStructure.NVIC_IRQChannel=UART5_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=3;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority=2;
    NVIC_InitStructure.NVIC_IRQChannelCmd=ENABLE;
    NVIC_Init(&NVIC_InitStructure);

    USART_ITConfig(UART5,USART_IT_RXNE,ENABLE);
    USART_Cmd(UART5,ENABLE);

}

在main函数中的调用是： uart5(28800); //波特率= 9600      使用的是JTAG去检验波特率，发现UART5的波特率时钟要设置为28800  才能匹配到9600的波特率！