stm32 TDOA源码

TDOA (Time Difference of Arrival) 是一种用于定位的技术，通常用于无线信号定位。对于 STM32，你可以使用它的定时器模块来实现 TDOA 算法。

这里提供一个基于 STM32 的 TDOA 算法的源码示例：

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

#define SOUND_SPEED 343.0
#define BUFFER_SIZE 256

volatile uint32_t overflow_counter = 0;
volatile uint32_t start_counter = 0;
volatile uint32_t end_counter = 0;

void TIM2_IRQHandler(void)
{
    if (TIM2->SR & TIM_SR_UIF)
    {
        overflow_counter++;
        TIM2->SR &= ~TIM_SR_UIF;
    }
}

void EXTI0_IRQHandler(void)
{
    if (EXTI->PR & EXTI_PR_PR0)
    {
        if (GPIOA->IDR & GPIO_IDR_ID0)
        {
            start_counter = (overflow_counter << 16) | TIM2->CNT;
        }
        else
        {
            end_counter = (overflow_counter << 16) | TIM2->CNT;
        }
        EXTI->PR |= EXTI_PR_PR0;
    }
}

int main(void)
{
    // 初始化定时器2
    RCC->APB1ENR |= RCC_APB1ENR_TIM2EN;
    TIM2->PSC = 83;
    TIM2->ARR = 0xFFFF;
    TIM2->CR1 |= TIM_CR1_CEN;

    // 初始化PA0作为输入引脚
    RCC->AHB1ENR |= RCC_AHB1ENR_GPIOAEN;
    GPIOA->MODER &= ~GPIO_MODER_MODE0;
    GPIOA->PUPDR &= ~GPIO_PUPDR_PUPD0;
    GPIOA->PUPDR |= GPIO_PUPDR_PUPD0_0;

    // 初始化EXTI0
    EXTI->IMR |= EXTI_IMR_MR0;
    EXTI->RTSR |= EXTI_RTSR_TR0;
    NVIC_EnableIRQ(EXTI0_IRQn);

    // 初始化USART2
    RCC->APB1ENR |= RCC_APB1ENR_USART2EN;
    GPIOA->AFR[0] |= GPIO_AFRL_AFRL2_1 | GPIO_AFRL_AFRL3_1;
    GPIOA->MODER |= GPIO_MODER_MODE2_1 | GPIO_MODER_MODE3_1;
    USART2->BRR = 0x1117; // 波特率为9600
    USART2->CR1 |= USART_CR1_TE | USART_CR1_RE | USART_CR1_UE;

    // 输出提示信息
    char buffer[BUFFER_SIZE];
    snprintf(buffer, BUFFER_SIZE, "TDOA Demo: Sound speed is %.2f m/s.\r\n", SOUND_SPEED);
    for (int i = 0; buffer[i] != '\0'; i++)
    {
        while (!(USART2->SR & USART_SR_TXE))
            ;
        USART2->DR = buffer[i];
    }

    while (1)
    {
        // 等待开始计时
        while (!start_counter)
            ;

        // 等待结束计时
        while (!end_counter)
            ;

        // 计算时间差
        uint32_t delta = end_counter - start_counter;
        float distance = SOUND_SPEED * delta / (2 * (1 << 16));

        // 输出距离
        snprintf(buffer, BUFFER_SIZE, "Distance: %.2f m.\r\n", distance);
        for (int i = 0; buffer[i] != '\0'; i++)
        {
            while (!(USART2->SR & USART_SR_TXE))
                ;
            USART2->DR = buffer[i];
        }

        // 清空计数器
        start_counter = 0;
        end_counter = 0;
    }
}

这个例子中，我们使用了 STM32 的定时器2来计算时间差。当收到外部中断时，我们记录下当前计数器的值，并在计算时间差时使用它们。最终，我们将距离通过 USART2 发送出来。

当然，这只是一个简单的示例，具体实现还需要根据你的具体需求进行调整。