一、超声波模块(HC-SR04)
所使用的超声波模块是HC-SR04,一个发射引脚(Trig),一个接收引脚(Echo),一个电源引脚(Vcc)和一个接地引脚(Gnd),如下图。

二、程序
1、ultrasonic.c程序
PC7接发射(Trig),PC8接接收(Echo)
#define TX PCout(7)
#define RX PCin(8)
u16 Time, T;
void Timer2_Init(void)
{
Time = 0;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
TIM_InternalClockConfig(TIM2);
TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInitStructure.TIM_Period = 7200 - 1;
TIM_TimeBaseInitStructure.TIM_Prescaler = 0;
TIM_TimeBaseInitStructure.TIM_RepetitionCounter = 0;
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseInitStructure);
TIM_ClearFlag(TIM2, TIM_FLAG_Update);
TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
NVIC_Init(&NVIC_InitStructure);
TIM_Cmd(TIM2, ENABLE);
}
void TIM2_IRQHandler(void)
{
if(TIM_GetITStatus(TIM2, TIM_IT_Update) == SET)
{
if(RX == 1)
{
Time++;
}
TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
}
}
void Ultra_Init(void)
{
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);
GPIO_InitTypeDef GPIO_InitStructure;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOC, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOC, &GPIO_InitStructure);
TX = 0;
}
u8 Ultra_Getvalue(void)
{
TX = 0;
Delay_us(45);
TX = 1;
Timer2_Init();
Delay_ms(100);
return ((Time*0.0001)*34000)/2;
}
2、main.c程序
被赋值的ucDist结果是以CM为单位的距离数据
int main(void)
{
Timer2_Init();
Ultra_Init();
while(1)
{
ucDist = Ultra_Getvalue();
}
}