stm32f103c8t6練習pwm（脈沖寬度調制）實驗，從網上找到一串代碼，稍作修改后運行，不能實現呼吸燈效果，僅僅是PB5,PB6 led燈初始化成功發光，初學stm32,新手上路，有諸多問題難解，還望大神賜教
代碼如下：
- #include "stm32f10x.h"
- #include "my.h"
- void RCC_cfg(void);
- void GPIO_cfg(void);
- void TIMER_cfg(void);
- void PWM_cfg(void);
- int led_fx=1;
- int led_dt=0;
-
-
- void LED_Init(void)
- {
- GPIO_InitTypeDef GPIO_InitStructure;
-
- RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB|RCC_APB2Periph_GPIOE, ENABLE); //使能PB,PE端口時鐘
-
- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_6; //LED0-->PB.5 端口配置
- GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; //推挽輸出
- GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //IO口速度為50MHz
- GPIO_Init(GPIOB, &GPIO_InitStructure); //根據設定參數初始化GPIOB.5
- GPIO_SetBits(GPIOB,GPIO_Pin_5 | GPIO_Pin_6 ); //PB.5 輸出高
- //PE.5 輸出高
- }
- int main(void)
- {
-
- RCC_cfg();
- GPIO_cfg();
- TIMER_cfg();
- PWM_cfg();
- //使能TIM2計時器，開始輸出PWM
- TIM_Cmd(TIM2, ENABLE);
- LED_Init();
- while(1)
- {
- delay_ms(5);
- if(led_fx==1)
- {
- led_dt++;
- }
- else
- {
- led_dt--;
- }
- if(led_dt>500) led_fx=0;
- if(led_dt==0) led_fx=1;
- TIM_SetCompare4(TIM2,led_dt);
- }
- }
- void RCC_cfg(void)
- {
- //定義錯誤狀態變量
- ErrorStatus HSEStartUpStatus;
- //將RCC寄存器重新設置為默認值
- RCC_DeInit();
- //打開外部高速時鐘晶振
- RCC_HSEConfig(RCC_HSE_ON);
- //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為系統時鐘源
- RCC_SYSCLKConfig(RCC_SYSCLKSource_PLLCLK);
- //判斷PLL是否是系統時鐘
- while(RCC_GetSYSCLKSource() != 0x08);
- }
- //開啟TIM2的時鐘
- RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2,ENABLE);
- //開啟GPIOB的時鐘和復用功能
- RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO,ENABLE);
- }
- void GPIO_cfg(void)
- {
- GPIO_InitTypeDef GPIO_InitStructure;
- // GPIO_PinRemapConfig(GPIO_PartialRemap1_TIM2, ENABLE); //映射引腳，默認PA3 ->TIM2_CH4因此不用映射
- //選擇引腳3
- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
- //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;
- //PA
- GPIO_Init(GPIOA,&GPIO_InitStructure);
- }
- void TIMER_cfg(void)
- {
- TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
- //重新將Timer設置為缺省值
- TIM_DeInit(TIM2);
- //采用內部時鐘給TIM2提供時鐘源
- TIM_InternalClockConfig(TIM2);
- //預分頻系數為0
- TIM_TimeBaseStructure.TIM_Prescaler = 0;
- //設置計數溢出大小
- TIM_TimeBaseStructure.TIM_Period = 500;
- //設置計數器模式為向上計數模式(+1)
- TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
- //設置時鐘分割
- TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
- //將配置應用到TIM2中
- TIM_TimeBaseInit(TIM2,&TIM_TimeBaseStructure);
- }
- void PWM_cfg(void)
- {
- 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 (Led亮度)
- TimOCInitStructure.TIM_Pulse = 0;
- //TIM輸出比較極性高
- TimOCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
- //使能輸出狀態
- TimOCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
- //TIM2的CH4輸出
- TIM_OC4Init(TIM2, &TimOCInitStructure);
- //設置TIM2的PWM輸出為使能
- TIM_CtrlPWMOutputs(TIM2,ENABLE);
- }
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