接下來就是解調。筆者用了兩次解調才把基帶信號完整復現出來。先來看看初步解調代碼,用的是TIM1的輸入捕獲模塊,TIM1屬于高級定時器,和通用定時器的代碼還是有些地方不一樣的,比如輸入捕獲中斷函數名為TIM1_CC_IRQHandler()。
void TIM1_Cap_Init(u16 arr,u16 psc) ? ? ? ?
{ ? ? ? ??
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef ?TIM_TimeBaseStructure;
TIM_ICInitTypeDef ?TIM1_ICInitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
?
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE); ? ? ? ?
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE); ?
?
GPIO_InitStructure.GPIO_Pin ?= GPIO_Pin_8; ?
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPD;?
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_ResetBits(GPIOA,GPIO_Pin_8); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ??
?
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(TIM1, &TIM_TimeBaseStructure);?
?
TIM1_ICInitStructure.TIM_Channel = TIM_Channel_1; //CC1S=01 ? ? ? ??
TIM1_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising; ? ? ? ?
TIM1_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;?
TIM1_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1; ? ? ? ??
TIM1_ICInitStructure.TIM_ICFilter = 0x00;
TIM_ICInit(TIM1, &TIM1_ICInitStructure);
NVIC_InitStructure.NVIC_IRQChannel = TIM1_CC_IRQn; ?
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2; ?
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; ?
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;?
NVIC_Init(&NVIC_InitStructure); ?
TIM_ITConfig(TIM1,TIM_IT_CC1,ENABLE);
TIM_Cmd(TIM1,ENABLE ); ? ? ? ??
}
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