void PWM3_Config(void){
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
uint16_t TimerPeriod = 0;
uint16_t Channel1Pulse = 0, Channel2Pulse = 0;
GPIO_InitTypeDef GPIO_InitStructure;
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6; //這里設置的輸出引腳為A6
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_Init(GPIOA,&GPIO_InitStructure);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource6, GPIO_AF_1); //F0還需要設置AF為功能1
TimerPeriod = (SystemCoreClock/17570)-1;
Channel1Pulse = (uint16_t)(((uint32_t)5*(TimerPeriod -1)) / 100); //這里設置了高電平的時長, 這個公式的意思其實是1/20的時長是高電平, 舉個例子, 現在F0的SystemCoreClock是48M, TimerPeriod=2700, 除以20, 就是136左右.
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_Period = TimerPeriod;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCPolarity_Low;
TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;
TIM_OCInitStructure.TIM_Pulse = Channel1Pulse;
TIM_OC1Init(TIM3, &TIM_OCInitStructure);
TIM_Cmd(TIM3, ENABLE);
TIM_CtrlPWMOutputs(TIM3, ENABLE);
}
如何動態配置PWM的占空比呢, 直接用調用一個函數:
TIM_SetCompare1(TIM3,2700); // 這個2700就是剛才設置的TimerPeriod, 即最大值為2700, 這個比較值要比2700小, 就是高電平, 也就是剛才的Pulse值其實就是相當於TIM_SetCompare1(TIM3,136); 即從0-136這段時間, 為高電平, 137-2700為低電平.