"盲人眼睛"的小制作利用超声波测距离怎么才能让蜂鸣器灵敏一些 -

#include <reg51.h>
#include <intrins.h>
sbit SDA=P3^6; // 此引脚须上拉 4.7K 电阻至 VCC
sbit SCL=P3^7; // 此引脚须上拉 4.7K 电阻至 VCC
sbit beep=P1^5;
unsigned int range=0;
//unsigned int range1=0;
//unsigned int range2=0;
//unsigned int range3=0;
//unsigned int min=0;
void delay50us_chengxv(void) //误差 0us
{
unsigned char a,b;
for(b=9;b>0;b--)
for(a=1;a>0;a--);
}
void delay500ms(void) //误差 0us
{
unsigned char a,b,c;
for(c=205;c>0;c--)
for(b=116;b>0;b--)
for(a=9;a>0;a--);
}
void delay300ms(void) //误差 0us
{
unsigned char a,b,c;
for(c=5;c>0;c--)
for(b=212;b>0;b--)
for(a=140;a>0;a--);
}
void beepcv()
{
unsigned int a;
if(range<=1500&&range>=0)
{
if(range<=1500&&range>=900)
{
for(a=600;a>0;a--)
{
beep=1;
delay1(10);
beep=0;
delay1(10);
delay1(175);
}
}
else if(range>=300&&range<900)
{
for(a=600;a>0;a--)
{
beep=1;
delay1(10);
beep=0;
delay1(10);
delay1(100);
}
}
else if(range>=0&&range<300)
{
for(a=600;a>0;a--)
{
beep=1;
delay1(10);
beep=0;
delay1(10);
delay1(50);
}
}
}
}
void delay(void) //short delay 使用速度较快的单片机时，I2C 通讯可能不正常，在此函数中多加 4～8 个_nop_();即可
{
_nop_(); _nop_(); _nop_(); _nop_();
_nop_(); _nop_(); _nop_(); _nop_();
_nop_(); _nop_(); _nop_(); _nop_();
_nop_(); _nop_(); _nop_(); _nop_();
}
void start(void) //I2C start
{
SDA = 1;
delay();
SCL = 1;
delay();
SDA = 0;
delay();
}
void stop(void) //I2C stop
{
SDA = 0;
delay();
SCL = 1;
delay();
SDA = 1;
delay();
}
void ack(void) //ack
{
unsigned char i;
SCL = 1;
delay();
while(SDA == 1 && i < 200)
{
i++;
}
SCL = 0;
delay();
}
void no_ack() //not ack
{
SDA = 1;
delay();
SCL = 1;
delay();
SCL = 0;
delay();
}
void i2c_write_byte(unsigned char dat) //write a byte
{
unsigned char i;
SCL = 0;
for(i = 0; i < 8; i++)
{
if(dat & 0x80)
{
SDA = 1;
}
else
{
SDA = 0;
}
dat = dat << 1;
delay();
SCL = 1;
delay();
SCL = 0;
delay();
}
SDA = 1;
delay();
}
unsigned char i2c_read_byte(void) //read a byte
{
unsigned char i,dat;
SCL = 0;
delay();
SDA = 1;
delay();
for(i = 0; i < 8; i++)
{
SCL = 1;
delay();
dat = dat << 1;
if(SDA == 1)
{
dat++;
}
SCL = 0;
delay();
}
return dat;
}
void init_i2c(void) //i2c init
{
SDA = 1;
SCL = 1;
}
void write_byte(unsigned char address,unsigned char reg,unsigned char command) //address+register+command
{
init_i2c();
start();
i2c_write_byte(address);
ack();
i2c_write_byte(reg);
ack();
i2c_write_byte(command);
ack();
stop();
}
unsigned char read_byte(unsigned char address,unsigned char reg) //address(with bit 0 set) + register
{
unsigned char dat;
init_i2c();
start();
i2c_write_byte(address);
ack();
i2c_write_byte(reg);
ack();
start();
i2c_write_byte(address+1);
ack();
delay();delay();delay();delay();delay(); //此处延时对于 STC89C 系列单片机，可以删除，如果对于快速单
//片机，需要加至少 50us 的延时，才可以可靠读到数据
dat = i2c_read_byte();
no_ack();
stop();
return dat;
}
void delayms(unsigned int ms) //delay ms
{
unsigned char i;
unsigned int j;
for(i=0;i<110;i++)
for(j=0;j<ms;j++);
}
/*void change_i2c_address(unsigned char addr_old, unsigned char addr_new)
// addr_old is the address now, addr_new will be the new address
{ //that you want change to
delayms(2000); // Protect the eeprom ,you can delete this sentence
write_byte(addr_old,2,0x9a);
delayms(1);
write_byte(addr_old,2,0x92);
delayms(1);
write_byte(addr_old,2,0x9e);
delayms(1);
write_byte(addr_old,2, addr_new);
delayms(500); //Protect the eeprom, you can delete this sentence
}
void config_0x71_0x7d(unsigned char addr_old, unsigned char flag)
//flag will be 0x71,0x72,0x73,0x74,0x7a,0x7b,0x7c,0x7d
{ //that you want change to
delayms(2000); // Protect the eeprom ,you can delete this sentence
write_byte(addr_old,2,0x9c);
delayms(1);
write_byte(addr_old,2,0x95);
delayms(1);
write_byte(addr_old,2,0x98);
delayms(1);
write_byte(addr_old,2, flag);
delayms(500); //Protect the eeprom, you can delete this sentence
}*/
unsigned int detect(unsigned char address,unsigned char command) //0xe8(address) + 0x30(command)
{
unsigned int distance,count;
write_byte(address,2,command); //use command "0x30" to detect the distance
delayms(1); //安全延时,如果显示不清晰可以将延时调大一些
//delayms(80); //如果是探测温度此处延时需根据表 1 所列时间相应延长
count=800;
while(--count || !SCL) //等待探测结束，count 值调小将减小探测等待时间
{
; // 空语句
// DigDisplay(range); //显示语句，可根据需要保留或删除
}
// while(!SCL)display(range); //you can delete "display(range)"
//通过查询 SCL 线来智能识别探测是否结束，使用本语句可删除上条语句(count=800;while…)以节省探测时间
distance=read_byte(address,2);
distance <<= 8;
distance += read_byte(address,3);
return distance; //return 16 bit distance in millimeter
}
void main(void)
{
//change_i2c_address(0xe8,0xfe); //change default address 0xe8 to 0xfe
while(1)
{
range = detect(0xe8,0x30);
//0xe8 is the address; 0x30 is the command.you just need the only one sentence to get the range.
beepcv();
}
}

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