STM32学习笔记（5）：通用定时器PWM输出

//等待外部高速时钟晶振工作

HSEStartUpStatus = RCC_WaitForHSEStartUp();

if(HSEStartUpStatus == SUCCESS)

{

//设置AHB时钟(HCLK)为系统时钟

RCC_HCLKConfig(RCC_SYSCLK_Div1);

//设置高速AHB时钟(APB2)为HCLK时钟

RCC_PCLK2Config(RCC_HCLK_Div1);

//设置低速AHB时钟(APB1)为HCLK的2分频

RCC_PCLK1Config(RCC_HCLK_Div2);

//设置FLASH代码延时

FLASH_SetLatency(FLASH_Latency_2);

//使能预取指缓存

FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);

//设置PLL时钟，为HSE的9倍频8MHz * 9 = 72MHz

RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);

//使能PLL

RCC_PLLCmd(ENABLE);

//等待PLL准备就绪

while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET);

//设置PLL为系统时钟源

RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);

//判断PLL是否是系统时钟

while(RCC_GetSYSCLKSource() != 0x08);

}

//开启TIM3的时钟

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE);

//开启GPIOB的时钟和复用功能

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB | RCC_APB2Periph_AFIO,ENABLE);

}

void GPIO_cfg()

{

GPIO_InitTypeDef GPIO_InitStructure;

//部分映射，将TIM3_CH2映射到PB5

//GPIO_PinRemapConfig(GPIO_FullRemap_TIM3, ENABLE);

GPIO_PinRemapConfig(GPIO_PartialRemap_TIM3, ENABLE);

//选择引脚5

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;

//输出频率最大50MHz

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

//复用推挽输出

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;

GPIO_Init(GPIOB,&GPIO_InitStructure);

}

void TIMER_cfg()

{

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

//重新将Timer设置为缺省值

TIM_DeInit(TIM3);

//采用内部时钟给TIM3提供时钟源

TIM_InternalClockConfig(TIM3);

//预分频系数为0，即不进行预分频，此时TIMER的频率为72MHz

TIM_TimeBaseStructure.TIM_Prescaler = 0;

//设置时钟分割

TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;

//设置计数器模式为向上计数模式

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

//设置计数溢出大小，每计7200个数就产生一个更新事件，即PWM的输出频率为10kHz

TIM_TimeBaseStructure.TIM_Period = 7200 - 1;

//将配置应用到TIM3中

TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStructure);

}

void PWM_cfg()

{

TIM_OCInitTypeDef TimOCInitStructure;

//设置缺省值

TIM_OCStructInit(&TimOCInitStructure);

//PWM模式1输出

TimOCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;

//设置占空比，占空比=(CCRx/ARR)*100%或(TIM_Pulse/TIM_Period)*100%

TimOCInitStructure.TIM_Pulse = dutyfactor * 7200 / 100;

//TIM输出比较极性高

TimOCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

//使能输出状态

TimOCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

//TIM3的CH2输出

TIM_OC2Init(TIM3, &TimOCInitStructure);

//设置TIM3的PWM输出为使能

TIM_CtrlPWMOutputs(TIM3,ENABLE);

}