使用STM32F407的UART库函数来实现openmv数据的接收和发送

以下是使用STM32F407的UART库函数来实现openmv数据的接收和发送的示例代码：

#include "stm32f4xx.h"
#include "stm32f4xx_usart.h"
#include "stm32f4xx_gpio.h"
#include "stm32f4xx_rcc.h"

#define BUFFER_SIZE 128

uint8_t rx_buffer[BUFFER_SIZE];
uint8_t tx_buffer[BUFFER_SIZE];

int main(void)
{
    USART_InitTypeDef USART_InitStructure;
    GPIO_InitTypeDef GPIO_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    // Enable GPIOA clock
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);

    // Enable USART2 clock
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2, ENABLE);

    // Configure USART2 TX pin (PA2) as alternate function push-pull
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
    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);

    // Configure USART2 RX pin (PA3) as input floating
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    // Connect USART2 TX pin to PA2
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource2, GPIO_AF_USART2);

    // Connect USART2 RX pin to PA3
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource3, GPIO_AF_USART2);

    // Configure USART2
    USART_InitStructure.USART_BaudRate = 9600;
    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_Init(USART2, &USART_InitStructure);

    // Enable USART2 receive interrupt
    USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);

    // Enable USART2
    USART_Cmd(USART2, ENABLE);

    // Enable USART2 IRQ
    NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);

    while (1)
    {
        // Check if there is data to send
        if (tx_buffer[0] != '\0')
        {
            // Send data
            USART_SendData(USART2, tx_buffer[0]);

            // Wait for transmission to complete
            while (USART_GetFlagStatus(USART2, USART_FLAG_TXE) == RESET);

            // Clear transmit buffer
            tx_buffer[0] = '\0';
        }
    }
}

void USART2_IRQHandler(void)
{
    static uint8_t rx_index = 0;

    if (USART_GetITStatus(USART2, USART_IT_RXNE) != RESET)
    {
        // Read data from USART2 receive data register
        rx_buffer[rx_index] = USART_ReceiveData(USART2);

        // Check for end of message character
        if (rx_buffer[rx_index] == '\n')
        {
            // Process message
            // ...

            // Clear receive buffer
            memset(rx_buffer, 0, sizeof(rx_buffer));

            // Reset receive index
            rx_index = 0;
        }
        else
        {
            // Increment receive index
            rx_index++;

            // Check for buffer overflow
            if (rx_index >= BUFFER_SIZE)
            {
                // Clear receive buffer
                memset(rx_buffer, 0, sizeof(rx_buffer));

                // Reset receive index
                rx_index = 0;
            }
        }
    }
}

void send_data(const char *data)
{
    // Copy data to transmit buffer
    strncpy((char *)tx_buffer, data, sizeof(tx_buffer));

    // Add end of message character
    strncat((char *)tx_buffer, "\n", sizeof(tx_buffer) - strlen((char *)tx_buffer) - 1);
}

在上面的示例代码中，首先使用库函数来初始化USART2和GPIOA。然后，使用NVIC_Init函数来初始化USART2的中断向量表，并使用USART_ITConfig函数来使能USART2的接收中断。在while循环中，通过检测tx_buffer数组中是否有要发送的数据来发送数据。在中断服务程序中，使用USART_GetITStatus函数来检测是否接收到了数据，并使用USART_ReceiveData函数来读取接收数据寄存器中的数据。如果接收到的数据是结束消息字符，则处理消息并清除接收缓冲区。如果接收到的数据不是结束消息字符，则将接收缓冲区索引递增，并检查接收缓冲区是否已满。如果接收缓冲区已满，则清除接收缓冲区并重置接收索引。最后，使用send_data函数来将数据添加到tx_buffer数组中，该函数会将数据复制到tx_buffer数组中，并在末尾添加结束消息字符。