STM 使用串口发送0xffBCD编码

好的，可以为您提供以下代码作为参考：

#include "stm32f4xx.h"
#include <stdio.h>

void USART2_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStruct;
    USART_InitTypeDef USART_InitStruct;
    NVIC_InitTypeDef NVIC_InitStruct;

    // Enable clock for GPIOA and USART2
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);

    // Initialize GPIO pins for USART TX and RX
    GPIO_InitStruct.GPIO_Pin = GPIO_Pin_2 | GPIO_Pin_3;
    GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStruct.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOA, &GPIO_InitStruct);

    // Connect the pins to the USART2 alternate function
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2); // USART2_TX
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2); // USART2_RX

    // Configure USART2
    USART_InitStruct.USART_BaudRate = 9600;
    USART_InitStruct.USART_WordLength = USART_WordLength_8b;
    USART_InitStruct.USART_StopBits = USART_StopBits_1;
    USART_InitStruct.USART_Parity = USART_Parity_No;
    USART_InitStruct.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_InitStruct.USART_Mode = USART_Mode_Tx;
    USART_Init(USART2, &USART_InitStruct);

    // Enable USART2 interrupt in NVIC
    NVIC_InitStruct.NVIC_IRQChannel = USART2_IRQn;
    NVIC_InitStruct.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStruct.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStruct.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStruct);

    // Enable USART2
    USART_Cmd(USART2, ENABLE);
}

void USART2_SendByte(uint8_t byte)
{
    // Wait until TX buffer is empty
    while (!(USART2->SR & USART_SR_TXE));

    // Send byte
    USART2->DR = byte;
}

void USART2_SendBCD(uint8_t bcd)
{
    uint8_t value = ((bcd >> 4) & 0x0F) * 10 + (bcd & 0x0F);
    USART2_SendByte(value);
}

int main(void)
{
    USART2_Init();

    // Send 0xFF BCD encoded
    USART2_SendBCD(0xFF);

    while (1)
    {
        // Do something
    }
}

在这个例子中，我们使用的是USART2来发送数据，通过调用USART2_SendBCD函数，将0xFF BCD编码发送出去。请注意，这里的波特率是9600，如果需要修改可以在USART_InitStruct结构体中进行修改。同时，为了简化代码，我们只实现了发送功能，如果需要接收数据，还需要在初始化时配置USART_Mode为USART_Mode_Rx。