STM32F407 openmv巡线传值 进行巡线代码

以下是一个简单的STM32F407与OpenMV进行巡线传值的示例代码：

#include "stm32f4xx.h"
#include "usart.h"

#define UART_BUFFER_SIZE 256

uint8_t uart_buffer[UART_BUFFER_SIZE];
volatile uint16_t uart_head = 0;
volatile uint16_t uart_tail = 0;

void USART3_IRQHandler(void)
{
    if(USART_GetITStatus(USART3, USART_IT_RXNE) != RESET)
    {
        uart_buffer[uart_head] = USART_ReceiveData(USART3);
        uart_head = (uart_head + 1) % UART_BUFFER_SIZE;
    }
}

void uart_send_byte(uint8_t byte)
{
    while(USART_GetFlagStatus(USART3, USART_FLAG_TXE) == RESET);
    USART_SendData(USART3, byte);
}

void uart_send_string(const char* str)
{
    while(*str)
    {
        uart_send_byte(*str++);
    }
}

int main(void)
{
    USART_Config();

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);
    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOC, &GPIO_InitStructure);

    USART_ITConfig(USART3, USART_IT_RXNE, ENABLE);
    NVIC_EnableIRQ(USART3_IRQn);

    uart_send_string("Ready to receive data...\r\n");

    while(1)
    {
        if(uart_head != uart_tail)
        {
            uint8_t command = uart_buffer[uart_tail];
            uart_tail = (uart_tail + 1) % UART_BUFFER_SIZE;

            if(command == 'L')
            {
                uint16_t left = ADC_GetConversionValue(ADC1);
                uart_send_string("Left: ");
                uart_send_string(itoa(left));
                uart_send_string("\r\n");
            }
            else if(command == 'C')
            {
                uint16_t center = ADC_GetConversionValue(ADC2);
                uart_send_string("Center: ");
                uart_send_string(itoa(center));
                uart_send_string("\r\n");
            }
            else if(command == 'R')
            {
                uint16_t right = ADC_GetConversionValue(ADC3);
                uart_send_string("Right: ");
                uart_send_string(itoa(right));
                uart_send_string("\r\n");
            }
        }
    }
}

在这个示例代码中，我们使用了STM32F407的USART3模块与OpenMV进行通讯。当OpenMV发送'L'、'C'或'R'这三个指令中的任意一个时，STM32F407会对应地读取PC0~PC3四个引脚的ADC值，并将其通过USART3发送回OpenMV。