void TIM3_Int_lnit(u16 arr,u16 psc)TIM TimeBaselnitTypeDef TIM TimeBaseStructureRCC_APB1PeriphClockCmd(RCC APB1Periph_TIM3,ENABLE);TIM_TimeBaseStructure.TIM_Period = arr;TIM TimeBaseStructure.TIM Prescaler =psc;TIM_TimeBaseStructure.TIM ClockDivision = 0TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;TIM_TimeBaselnit(TIM3, &TIM_TimeBaseStructure);TIM Cmd(TIM3,ENABLE);//TIM3的 PWM输出初始化void TIM3_PWM_Init(u16 arr,u16 psc)TIM_TimeBaselnitTypeDef TIM_TimeBaseStructure;TIM_OCInitTypeDef TIM_OClnitStructure;TIM TimeBaseStructure.TIM Period = arrTIM_TimeBaseStructure.TIM_Prescaler =pscTIM TimeBaseStructure.TIM_ClockDivision = 0;TIM TimeBaseStructure.TIM CounterMode = TIM CounterMode Up;TIM_TimeBaselnit(TIM3, &TIM_TimeBaseStructure); TIM OCInitStructure.TIM OCMode = TIM OCMode PWM2; TIM OCInitStructure.TIM OutputState = TIM OutputState Enable TIM OCInitStructure.TIM OCPolarity = TIMOCPolarity_High; TIM_OC2Init(TIM3,&TIM_OCInitStructure);TIM OC2PreloadConfig(TIM3, TIM OCPreload Enable);TIM Cmd(TIM3.ENABLE): 请说明:(1) 若设置PWM 频率为10K,则TIM3 PWM nit() 如何设置形参?(2)若利用 PA8，PA9，PA10 输出频率为 10K，占空比分别为20%，35%，50%的脉冲信号(利用定时器 1)，请参考 函数TIM3_PWM_Init(u16 arr,u16 psc)和 调用函数TIM SetCompare1(),TIM SetCompare2( )TIM SetCompare3()来完成编程。

(1) 若设置PWM频率为10K，则arr和psc的取值分别为：

arr = 84000000 / (10 * 1000 * psc) - 1

其中，84000000是STM32的主频，10是要求的PWM频率，1000是转换为kHz的系数，psc是预分频系数。解上式可得：

psc = 83

arr = 99

因此，TIM3_PWM_Init函数的形参应设置为：

TIM3_PWM_Init(99, 83)

(2) 利用定时器1，PA8、PA9、PA10分别对应TIM1_CH1、TIM1_CH2、TIM1_CH3，因此需要在TIM1_PWM_Init函数中设置对应通道的PWM输出。具体实现代码如下：

void TIM1_PWM_Init(u16 arr, u16 psc) {
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);

TIM_TimeBaseStructure.TIM_Period = arr;
TIM_TimeBaseStructure.TIM_Prescaler = psc;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

TIM_OCInitStructure.TIM_Pulse = arr * 0.2; // 20% 占空比
TIM_OC1Init(TIM1, &TIM_OCInitStructure);
TIM_OC1PreloadConfig(TIM1, TIM_OCPreload_Enable);

TIM_OCInitStructure.TIM_Pulse = arr * 0.35; // 35% 占空比
TIM_OC2Init(TIM1, &TIM_OCInitStructure);
TIM_OC2PreloadConfig(TIM1, TIM_OCPreload_Enable);

TIM_OCInitStructure.TIM_Pulse = arr * 0.5; // 50% 占空比
TIM_OC3Init(TIM1, &TIM_OCInitStructure);
TIM_OC3PreloadConfig(TIM1, TIM_OCPreload_Enable);

TIM_Cmd(TIM1, ENABLE);
}

然后，在需要输出PWM信号的地方，调用TIM_SetCompare函数即可。例如，要输出20%占空比的PWM信号，可以调用：

TIM_SetCompare1(TIM1, arr * 0.2);

注意，arr和psc的取值仍然需要根据要求的PWM频率来计算。