//說明:利用TIMER1的CH1即PA8端口輸出PWM驅動蜂鳴器。以下是代碼(在STM32F103上應用的)
void fn_pwm_init(INT16U _pwmFreq)
{
//ToDo: Add your code Here:
/* Timer1 Channel 1, PA8 IO初始化*/
GPIO_PinRemapConfig(GPIO_PartialRemap_TIM1,ENABLE);
GPIO_InitTypeDef GPIO_InitStructure;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOA, &GPIO_InitStructure);
//RCC的TIM1及IO時鐘開啓
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO,ENABLE);
//以下爲TIM1初始化
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
//重新將Timer設置爲缺省值
TIM_DeInit(TIM1);
//採用內部時鐘給TIM1提供時鐘源
TIM_InternalClockConfig(TIM1);
//預分頻係數爲0即不進行預分頻此時TIMER的頻率爲48MHz
TIM_TimeBaseStructure.TIM_Prescaler = 1-1;//1分頻,即不分頻
//設置時鐘分割
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
//設置計數器模式爲向上計數模式
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
//設置計數溢出大小48000000爲系統時鐘
TIM_TimeBaseStructure.TIM_Period = (48000000/_pwmFreq)- 1;
//將配置應用到TIM1中
TIM_TimeBaseInit(TIM1,&TIM_TimeBaseStructure);
//pwm初始化
TIM_OCInitTypeDef TimOCInitStructure; //設置缺省值
TIM_OCStructInit(&TimOCInitStructure); //PWM模式1輸出
TimOCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; //設置佔空比佔空比=(CCRx/ARR)*100%或(TIM_Pulse/TIM_Period)*100%
TimOCInitStructure.TIM_Pulse = 50 * 4800 / 100; //50爲100分比,1-100
TimOCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //使能輸出狀態
TimOCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //TIM1的CH1輸出
TIM_OC1Init(TIM1, &TimOCInitStructure); //設置TIM1的PWM輸出爲使能
TIM_CtrlPWMOutputs(TIM1,DISABLE);
}
void fn_pwm_Cmd(FunctionalState NewState)
{
//ToDo: Add your code Here:
TIM_CtrlPWMOutputs(TIM1, NewState);
TIM_Cmd(TIM1, NewState);
}