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利用tim3生成ev1527編碼(270K,1200us) TIM3_PWM_Init(1199,71); //分頻后1us,窄脈沖4LCK,寬脈沖12LCK,脈沖周期16LCK;同步周期128LCK(4LCK脈沖，124LCK空白);待生成脈沖周期為1200us //通過改變TIM3->CCR2的值來改變占空比 #define LED0_PWM_DUTY TIM3->CCR2 #define PULSE_CODE 0xD2F672 unsigned int pulse_count=0; void TIM3_PWM_Init(u16 arr,u16 psc) { GPIO_InitTypeDef GPIO_InitStructure; TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure; TIM_OCInitTypeDef TIM_OCInitStructure; NVIC_InitTypeDef NVIC_InitStructure; RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE); //①使能定時器 3時鐘 RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB| RCC_APB2Periph_AFIO, ENABLE); //①使能 GPIO 和 AFIO 復(fù)用功能時鐘 GPIO_PinRemapConfig(GPIO_PartialRemap_TIM3,ENABLE); //②重映射 TIM3_CH2->PB5 //設(shè)置該引腳為復(fù)用輸出功能,輸出 TIM3 CH2的 PWM 脈沖波形 GPIOB.5 GPIO_InitStructure.GPIO_Pin =GPIO_Pin_5; //TIM_CH2 GPIO_InitStructure.GPIO_Mode =GPIO_Mode_AF_PP; //復(fù)用推挽輸出 GPIO_InitStructure.GPIO_Speed =GPIO_Speed_50MHz; GPIO_Init(GPIOB,&GPIO_InitStructure); //①初始化 GPIO //初始化 TIM3 TIM_TimeBaseStructure.TIM_Period =arr; //設(shè)置在自動重裝載周期值 TIM_TimeBaseStructure.TIM_Prescaler=psc; //設(shè)置預(yù)分頻值 TIM_TimeBaseStructure.TIM_ClockDivision =0; //設(shè)置時鐘分割:TDTS = Tck_tim TIM_TimeBaseStructure.TIM_CounterMode =TIM_CounterMode_Up; //TIM 向上計數(shù)模式 TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStructure); //③初始化 TIMx //初始化 TIM3 Channel2 PWM模式 TIM_OCInitStructure.TIM_OCMode =TIM_OCMode_PWM1; //選擇 PWM 模式 1 TIM_OCInitStructure.TIM_OutputState =TIM_OutputState_Enable; //比較輸出使能 TIM_OCInitStructure.TIM_OCPolarity =TIM_OCPolarity_High; //輸出極性高 TIM_OCInitStructure.TIM_Pulse = 1200; TIM_OC2Init(TIM3,&TIM_OCInitStructure); //④初始化外設(shè) TIM3 OC2 TIM_OC2PreloadConfig(TIM3,TIM_OCPreload_Enable); //使能預(yù)裝載寄存器 NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn; NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure); TIM_ClearFlag(TIM3,TIM_IT_Update); TIM_ITConfig(TIM3,TIM_IT_Update, ENABLE); TIM_Cmd(TIM3, ENABLE); //⑤使能 TIM3 } void TIM3_IRQHandler(void) { if(TIM_GetITStatus(TIM3, TIM_IT_Update) == SET) { TIM_ClearITPendingBit(TIM3,TIM_IT_Update); if(pulse_count<24) //編碼部分 { if(PULSE_CODE&(1<<(23-pulse_count))) //按位判斷PULSE_CODE的二進制從前面開始，如果當(dāng)前位==1，寬脈沖900，==，窄脈沖300 { LED0_PWM_DUTY = 900; pulse_count++; } else { LED0_PWM_DUTY= 300; pulse_count++; } } elseif(pulse_count == 24) //同步頭 { LED0_PWM_DUTY= 300; pulse_count++; } elseif(pulse_count<31) //同步低電平部分 { LED0_PWM_DUTY= 0; pulse_count++; } else { LED0_PWM_DUTY= 0; pulse_count= 0; } } }
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