接下來就是解調(diào)。筆者用了兩次解調(diào)才把基帶信號(hào)完整復(fù)現(xiàn)出來。先來看看初步解調(diào)代碼，用的是TIM1的輸入捕獲模塊，TIM1屬于高級(jí)定時(shí)器，和通用定時(shí)器的代碼還是有些地方不一樣的，比如輸入捕獲中斷函數(shù)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 ); ? ? ? ??

}