编写代码基于stm32f407设计通过按键中断方式来实现对灯光亮度调升和调降，灯光亮度的调节需要设置PWM来调节占空比来调节灯五个不同挡位显现不用的五个灯光亮度；其中，KEY1可以增强亮度等级最亮不再增强，KEY2按键可以降低亮度等级，最暗不再减弱。

好的，以下是基于stm32f407的代码实现。

首先，需要初始化GPIO口和TIM定时器，代码如下：

#include "stm32f4xx.h"

// 定义LED灯亮度对应的占空比
#define DUTY_1 10 // 10%
#define DUTY_2 30 // 30%
#define DUTY_3 50 // 50%
#define DUTY_4 70 // 70%
#define DUTY_5 90 // 90%

// 定义当前灯光亮度等级
uint8_t current_level = 3; // 初始亮度等级为3

// 初始化GPIO口和TIM定时器
void LED_Init(void)
{
    // 打开GPIOG和TIM3时钟
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOG, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);

    // 配置GPIOG13为TIM3_CH2复用模式
    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOG, &GPIO_InitStructure);
    GPIO_PinAFConfig(GPIOG, GPIO_PinSource13, GPIO_AF_TIM3);

    // 配置TIM3
    TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
    TIM_TimeBaseInitStructure.TIM_Period = 1000 - 1; // PWM周期为1ms
    TIM_TimeBaseInitStructure.TIM_Prescaler = 84 - 1; // 时钟预分频为84
    TIM_TimeBaseInitStructure.TIM_ClockDivision = 0;
    TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseInitStructure);

    // 配置TIM3_CH2为PWM输出模式
    TIM_OCInitTypeDef TIM_OCInitStructure;
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStructure.TIM_Pulse = 0;
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OC2Init(TIM3, &TIM_OCInitStructure);

    // 启动TIM3
    TIM_Cmd(TIM3, ENABLE);
}

接下来，需要编写中断处理函数，用于处理按键中断事件，代码如下：

// 中断处理函数
void EXTI0_IRQHandler(void)
{
    if (EXTI_GetITStatus(EXTI_Line0) != RESET) // 判断是否为KEY1按键中断
    {
        EXTI_ClearITPendingBit(EXTI_Line0); // 清除中断标志位

        if (current_level < 5) // 如果当前亮度等级小于5，则增加亮度等级
        {
            current_level++;
        }

        switch (current_level) // 根据当前亮度等级设置占空比
        {
            case 1:
                TIM_SetCompare2(TIM3, DUTY_1);
                break;
            case 2:
                TIM_SetCompare2(TIM3, DUTY_2);
                break;
            case 3:
                TIM_SetCompare2(TIM3, DUTY_3);
                break;
            case 4:
                TIM_SetCompare2(TIM3, DUTY_4);
                break;
            case 5:
                TIM_SetCompare2(TIM3, DUTY_5);
                break;
        }
    }

    if (EXTI_GetITStatus(EXTI_Line1) != RESET) // 判断是否为KEY2按键中断
    {
        EXTI_ClearITPendingBit(EXTI_Line1); // 清除中断标志位

        if (current_level > 1) // 如果当前亮度等级大于1，则减小亮度等级
        {
            current_level--;
        }

        switch (current_level) // 根据当前亮度等级设置占空比
        {
            case 1:
                TIM_SetCompare2(TIM3, DUTY_1);
                break;
            case 2:
                TIM_SetCompare2(TIM3, DUTY_2);
                break;
            case 3:
                TIM_SetCompare2(TIM3, DUTY_3);
                break;
            case 4:
                TIM_SetCompare2(TIM3, DUTY_4);
                break;
            case 5:
                TIM_SetCompare2(TIM3, DUTY_5);
                break;
        }
    }
}

最后，需要在`main`函数中初始化GPIO口和TIM定时器，并配置KEY1和KEY2按键的中断，代码如下：

int main(void)
{
    // 初始化GPIO口和TIM定时器
    LED_Init();

    // 初始化KEY1和KEY2按键对应的GPIO口
    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    // 配置KEY1和KEY2按键对应的中断
    EXTI_InitTypeDef EXTI_InitStructure;
    NVIC_InitTypeDef NVIC_InitStructure;
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);
    SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOA, EXTI_PinSource0);
    EXTI_InitStructure.EXTI_Line = EXTI_Line0;
    EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;
    EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;
    EXTI_InitStructure.EXTI_LineCmd = ENABLE;
    EXTI_Init(&EXTI_InitStructure);
    NVIC_InitStructure.NVIC_IRQChannel = EXTI0_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x00;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x00;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
    SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOA, EXTI_PinSource1);
    EXTI_InitStructure.EXTI_Line = EXTI_Line1;
    EXTI_Init(&EXTI_InitStructure);
    NVIC_InitStructure.NVIC_IRQChannel = EXTI1_IRQn;
    NVIC_Init(&NVIC_InitStructure);

    while (1)
    {
    }
}

这样，就完成了基于stm32f407的灯光亮度调升和调降的代码编写。