stm32怎样增加两个按键控制PWM占空比的增与减实现LED亮度调节？

在利用定时器实现PWM输出，控制LED渐变的情况下，怎样增加两个按键控制PWM占空比的增与减实现LED亮度调节？用stm32f103

通过改变计数值

TIM_DeInit(TIM1);   /*TIM1时钟配置*/  TIM_TimeBaseStructure.TIM_Prescaler = 72;      //预分频(时钟分频)72M/72=1000K  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //向上计数  TIM_TimeBaseStructure.TIM_Period = 2000;       //装载值 1000k/2000=500hz  TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;  TIM_TimeBaseStructure.TIM_RepetitionCounter = 0x0;  TIM_TimeBaseInit(TIM1,&TIM_TimeBaseStructure);   /* Channel 1 Configuration in PWM mode */  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;     //PWM模式2  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;  //正向通道有效  TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;//反向通道无效  TIM_OCInitStructure.TIM_Pulse = 300;        //占空时间  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;   //输出极性  TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;     //互补端的极性   TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;  TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;    TIM_OC1Init(TIM1,&TIM_OCInitStructure);       //通道1  

TIM_DeInit(TIM1);   /*TIM1时钟配置*/  TIM_TimeBaseStructure.TIM_Prescaler = 72;      //预分频(时钟分频)72M/72=1000K  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //向上计数  TIM_TimeBaseStructure.TIM_Period = 2000;       //装载值 1000k/2000=500hz  TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;  TIM_TimeBaseStructure.TIM_RepetitionCounter = 0x0;  TIM_TimeBaseInit(TIM1,&TIM_TimeBaseStructure);   /* Channel 1 Configuration in PWM mode */  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;     //PWM模式2  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;  //正向通道有效  TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;//反向通道无效  TIM_OCInitStructure.TIM_Pulse = 300;        //占空时间  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;   //输出极性  TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;     //互补端的极性   TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;  TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;    TIM_OC1Init(TIM1,&TIM_OCInitStructure);       //通道1  

TIM_DeInit(TIM1);

/*TIM1时钟配置*/
TIM_TimeBaseStructure.TIM_Prescaler = 72;      //预分频(时钟分频)72M/72=1000K
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //向上计数
TIM_TimeBaseStructure.TIM_Period = 2000;       //装载值 1000k/2000=500hz
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseStructure.TIM_RepetitionCounter = 0x0;
TIM_TimeBaseInit(TIM1,&TIM_TimeBaseStructure);

/* Channel 1 Configuration in PWM mode */
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;     //PWM模式2
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;  //正向通道有效
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;//反向通道无效
TIM_OCInitStructure.TIM_Pulse = 300;        //占空时间
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;   //输出极性
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;     //互补端的极性
TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;

TIM_OC1Init(TIM1,&TIM_OCInitStructure);       //通道1


按键改变300作为变量     TIM_OCInitStructure.TIM_Pulse = 300;        //占空时间

感觉题目没有讲明白？LED渐变时，再增加两个按键，再原来基础上再增加或降低亮度？调整占空比和频率

通过两个按键直接调节定时器大小的值即可

可以在按键函数加上   TIM_SetCompare1(TIM3,i);   这个函数，这个可以改变PWM的占空比  TM3是对应定时器，i  是你想要修改的值，，要小于定时器的定时计数值