编写一个用TIM定时器实现stm32的跑马灯实验代码，要能适用战舰3开发板

好的，以下是用TIM定时器实现stm32的跑马灯实验代码：

#include "stm32f4xx.h"

void TIM_Configuration(void)
{
    TIM_TimeBaseInitTypeDef TIM_InitStructure;
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

    TIM_InitStructure.TIM_Period = 500 - 1;
    TIM_InitStructure.TIM_Prescaler = 42000 - 1;
    TIM_InitStructure.TIM_ClockDivision = 0;
    TIM_InitStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_InitStructure);

    TIM_Cmd(TIM2, ENABLE);
}

void LED_Configuration(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOF, ENABLE);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9 | GPIO_Pin_10 | GPIO_Pin_11 | GPIO_Pin_12;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOF, &GPIO_InitStructure);
}

void Delay(__IO uint32_t nCount)
{
    while(nCount--)
    {
    }
}

int main(void)
{
    TIM_Configuration();
    LED_Configuration();

    uint16_t LED_GPIO_Pin[] = {GPIO_Pin_9, GPIO_Pin_10, GPIO_Pin_11, GPIO_Pin_12};
    uint8_t LED_on_index = 0;
    while(1)
    {
        if(TIM_GetFlagStatus(TIM2, TIM_FLAG_Update) != RESET)
        {
            TIM_ClearFlag(TIM2, TIM_FLAG_Update);
            GPIO_SetBits(GPIOF, LED_GPIO_Pin[LED_on_index]);
            Delay(0xFFFFF);
            GPIO_ResetBits(GPIOF, LED_GPIO_Pin[LED_on_index]);
            if(++LED_on_index >= 4)
            {
                LED_on_index = 0;
            }
        }
    }
}

这份代码使用了TIM2定时器，将其预分频为42000，计数器自动重载值为500，每次计数器溢出时，会通过中断来触发LED的跑马灯效果。注意，这份代码使用的是战舰3开发板上的PF9, PF10, PF11, PF12四个IO口，你需要根据实际硬件资源进行修改。