//等待外部高速時鐘晶振工作

HSEStartUpStatus = RCC_WaitForHSEStartUp();

if(HSEStartUpStatus == SUCCESS)

{

//設置AHB時鐘(HCLK)為系統(tǒng)時鐘

RCC_HCLKConfig(RCC_SYSCLK_Div1);

//設置高速AHB時鐘(APB2)為HCLK時鐘

RCC_PCLK2Config(RCC_HCLK_Div1);

//設置低速AHB時鐘(APB1)為HCLK的2分頻

RCC_PCLK1Config(RCC_HCLK_Div2);

//設置FLASH代碼延時

FLASH_SetLatency(FLASH_Latency_2);

//使能預取指緩存

FLASH_PrefetchBufferCmd(FLASH_PrefetchBuffer_Enable);

//設置PLL時鐘，為HSE的9倍頻8MHz * 9 = 72MHz

RCC_PLLConfig(RCC_PLLSource_HSE_Div1, RCC_PLLMul_9);

//使能PLL

RCC_PLLCmd(ENABLE);

//等待PLL準備就緒

while(RCC_GetFlagStatus(RCC_FLAG_PLLRDY) == RESET);

//設置PLL為系統(tǒng)時鐘源

RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);

//判斷PLL是否是系統(tǒng)時鐘

while(RCC_GetSYSCLKSource() != 0x08);

}

//開啟TIM3的時鐘

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE);

//開啟GPIOB的時鐘和復用功能

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB | RCC_APB2Periph_AFIO,ENABLE);

}

void GPIO_cfg()

{

GPIO_InitTypeDef GPIO_InitStructure;

//部分映射，將TIM3_CH2映射到PB5

//GPIO_PinRemapConfig(GPIO_FullRemap_TIM3, ENABLE);

GPIO_PinRemapConfig(GPIO_PartialRemap_TIM3, ENABLE);

//選擇引腳5

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;

//輸出頻率最大50MHz

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

//復用推挽輸出

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;

GPIO_Init(GPIOB,&GPIO_InitStructure);

}

void TIMER_cfg()

{

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

//重新將Timer設置為缺省值

TIM_DeInit(TIM3);

//采用內部時鐘給TIM3提供時鐘源

TIM_InternalClockConfig(TIM3);

//預分頻系數(shù)為0，即不進行預分頻，此時TIMER的頻率為72MHz

TIM_TimeBaseStructure.TIM_Prescaler = 0;

//設置時鐘分割

TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;

//設置計數(shù)器模式為向上計數(shù)模式

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

//設置計數(shù)溢出大小，每計7200個數(shù)就產(chǎn)生一個更新事件，即PWM的輸出頻率為10kHz

TIM_TimeBaseStructure.TIM_Period = 7200 - 1;

//將配置應用到TIM3中

TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStructure);

}

void PWM_cfg()

{

TIM_OCInitTypeDef TimOCInitStructure;

//設置缺省值

TIM_OCStructInit(&TimOCInitStructure);

//PWM模式1輸出

TimOCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;

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

TimOCInitStructure.TIM_Pulse = dutyfactor * 7200 / 100;

//TIM輸出比較極性高

TimOCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

//使能輸出狀態(tài)

TimOCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

//TIM3的CH2輸出

TIM_OC2Init(TIM3, &TimOCInitStructure);

//設置TIM3的PWM輸出為使能

TIM_CtrlPWMOutputs(TIM3,ENABLE);

}