给出通过STM32控制继电器定时开关的代码

以下是通过STM32控制继电器定时开关的代码：

#include "stm32f10x.h"

GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_InitStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;

int main(void)
{
    // Enable GPIOB and TIM2 clock
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

    // Configure PB0 as output push-pull
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);

    // Configure TIM2 time base
    TIM_InitStructure.TIM_Period = 1000 - 1;
    TIM_InitStructure.TIM_Prescaler = 7200 - 1;
    TIM_InitStructure.TIM_ClockDivision = 0;
    TIM_InitStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_InitStructure);

    // Configure TIM2 channel 1 as output compare toggle mode
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle;
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_Pulse = 500;
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OC1Init(TIM2, &TIM_OCInitStructure);

    // Start TIM2
    TIM_Cmd(TIM2, ENABLE);

    while(1) {
        // Do nothing
    }

    return 0;
}

注意：本代码仅供参考，具体应用中需要对时钟、GPIO、定时器等进行配置，并根据实际需求修改。