stm32F207 请问为什么PWM输出LED灯亮度没有改变

z1qsx · 发表于 2014-12-19 12:30:37

[mw_shl_code=c,true] #include "main.h" static void Delay_ARMJISHU(__IO uint32_t nCount) { for (; nCount != 0; nCount--) { } } void usart_init(u32 bound) { NVIC_InitTypeDef NVIC_Initstrure; USART_InitTypeDef USART_InitStructure; RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1,ENABLE); USART_InitStructure.USART_BaudRate=bound; USART_InitStructure.USART_WordLength=USART_WordLength_8b; USART_InitStructure.USART_StopBits=USART_StopBits_1; USART_InitStructure.USART_Parity=USART_Parity_No; USART_InitStructure.USART_HardwareFlowControl=USART_HardwareFlowControl_None; USART_InitStructure.USART_Mode=USART_Mode_Rx | USART_Mode_Tx; USART_Init(USART1, &USART_InitStructure); //USART_ITConfig(USART1,USART_IT_RXNE,ENABLE); USART_Cmd(USART1,ENABLE);//?????®?? } void Pwm_Gpio_Config(void) { GPIO_InitTypeDef GPIO_InitStructure; RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOF, ENABLE); /*GPIOB_Pin_9, TIM4_Channel4 PWM*/ GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz; GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP; GPIO_Init(GPIOF, &GPIO_InitStructure); GPIO_PinAFConfig(GPIOF, GPIO_PinSource9, GPIO_AF_TIM3);//GPIOB_Pin9 TIM4_Ch4N, } void TIME_config(u32 arr,u32 psc) { TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure; RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE); TIM_TimeBaseStructure.TIM_Period=arr; TIM_TimeBaseStructure.TIM_Prescaler=psc; TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1; TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up; TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStructure); TIM_ITConfig(TIM3,TIM_IT_Update,ENABLE); TIM_CtrlPWMOutputs(TIM3, ENABLE); TIM_Cmd(TIM3,ENABLE); } void TIM3_OCInit() { TIM_OCInitTypeDef TIM_OCInitStructure; TIM_OCInitStructure.TIM_OCMode=TIM_OCMode_PWM1; TIM_OCInitStructure.TIM_OutputState=TIM_OutputState_Enable; TIM_OCInitStructure.TIM_OCPolarity=TIM_OCPolarity_Low; TIM_OCInitStructure.TIM_Pulse=200; TIM_OC1Init(TIM3,&TIM_OCInitStructure); TIM_ARRPreloadConfig(TIM3,ENABLE); TIM_OC1PreloadConfig(TIM3,TIM_OCPreload_Enable); TIM_Cmd(TIM3,ENABLE); } void NVIC_config() { NVIC_InitTypeDef NVIC_Initstrure; NVIC_Initstrure.NVIC_IRQChannel=TIM3_IRQn; NVIC_Initstrure.NVIC_IRQChannelCmd=ENABLE; NVIC_Initstrure.NVIC_IRQChannelPreemptionPriority=3; NVIC_Initstrure.NVIC_IRQChannelSubPriority=ENABLE; NVIC_Init(&NVIC_Initstrure); } void TIM3_IRQHandler(void) { if(TIM_GetITStatus(TIM3,TIM_IT_Update)!=RESET) { TIM_ClearITPendingBit(TIM3,TIM_IT_Update);//????????±ê???? } } main() { u16 led0pwmval=0; u8 dir=1; TIM3_OCInit() ; usart_init(115200); NVIC_config(); TIME_config(200,0); Pwm_Gpio_Config(); while(1) { Delay_ARMJISHU(6000); if(dir)led0pwmval++; else led0pwmval--; if(led0pwmval>300)dir=0; if(led0pwmval==0)dir=1; TIM_SetCompare1(TIM3,led0pwmval); } }[/mw_shl_code]