原创 用TOF10120飞行时间传感器和Arduino构建一个工业级智能停车系统

本项目是一个采用Traffic LED模块、Arduino Uno/Nano，以及TOF10120飞行时间传感器的工业级智能停车系统。项目采用一块切边的垫子作为停车区，先测量垫子长度，再根据这个数值定义不同距离的代码，一个接一个的点亮（ON）和熄灭（OFF）这些LEDs，以帮助司机安全停车：

当汽车即将进入停车区域时，绿色LED点亮。然后，黄色LED点亮，提醒司机即将接近目标停车位置，这表明汽车车身已经有一半位于停车区域。

当红色LED开始闪烁时，警告司机缓慢行驶并留意，到达停车点后关闭汽车，或者继续移动直到红色LED停止闪烁。

作为一个用以理解停车系统的原型，项目使用的均为廉价元件。读者可对电路进行升级，如改变代码中的测量距离数值，甚至替换电路中的传感器等，使项目更加实用。

tof10120激光模块最大的优势在于测距远、操作简单，程序中仅仅需要通过单片机给模块串口发送命令字符串，就可以向单片机发送回距离数据。如果发送自动测距的字符串命令，则模块会按照一定频率自动回送数据，相关物理量都可以通过命令字符串设置。传感器仅需要串口就可以实现。

TOF10120基于Sharp低成本标准CMOS工艺和SPAD技术，可为自动对焦（AF）提供精确、可重复的长距离测量，测量结果不受物体反射的影响。主要特点包括：

・采用940nm激光；

・小型陶瓷封装（20×13.2×2.0mm）；

・ 可在室内测量长达1.8m长度，精度5％；

・测量距离不受姆堡反射的影响；

・先进广促俄串扰补偿技术；

・30ms高速测量；

・单电源供电；

・Txd接口用于设备控制和数据传送；

・无铅，符合RoHS指令。

TOF10120典型测距范围为100-1800mm，电源电压3-5v，消耗电流35mA，兼容Arduino、ESP8266、ESP32等5V和3.3V控制板，适合-20°C to +70°C等室内外环境。

TOF10120支持UART、I2C通讯，1#引脚、2#引脚、3#引脚、4#引脚、5#引脚、6#引脚分别为GND、VDD、RXD、TXD、SDA、SCL。在六个引脚中，本项目只使用了其中的GND, VDD, SDA, and SCL四个脚。

根据数据表，TOF10120的I2C地址为0xA4，但寻址采用高7bit即0x52，这相当于82。

该模块为司机提供指示，本身带有限流电阻，无需额外连接电阻器。

模块共有4个公头，GND引脚链接与控制器的GND引脚，或数字引脚。这样，5v信号将熄灭模块，GND or LOW电平信号将启动模块。其中，R标号代表红色LED, Y标号代表黄色LED，G标号代表绿色LED，高电平信号时LED点亮。

首先，按照电路图，5V电源由LM7805三端稳压器提供给Arduino Nano，后面需要连接一个470uF的去耦铝电解电容器。

其中，5v稳压连接到Arduino Nano的VIN引脚，TOF10120激光测距模块的SCL、SDA引脚分别连接于Arduino板子的A5、A4引脚，电源线链接于Arduino板子的5V和接地引脚。

信号灯LED模块的GND引脚链接到Arduino板子的5号引脚，红色LED链接到Arduino的4号引脚，黄色LED连接到3号引脚，绿色LED连接到2号引脚。

接下来，设计Arduino Nano PCB开发板，母头用于3.3V、12V、5V和接地，左侧作为Vero板用来焊接其他电子元件，Arduino Nano的左右两侧都设计母头来连接跳线，也可连接传感器和电子元器件，例如TOF10120传感器和OLED显示模块的I2C引脚。

最后，将Traffic LED模块连接于Arduino板子的5、4、3、2引脚，再用公头连来连接TOF10120传感器的GND、Vdd、SCL、SDA引线。

做完上述连接后，就使用下述代码进行I2C寻址：

#include

void setup()

{

Wire.begin();

Serial.begin(115200);

Serial.println("\nI2C Scanner");

}

void loop()

{

byte error, address;

int nDevices;

Serial.println("Scanning...");

nDevices = 0;

for(address = 0; address <= 127; address++ )

{

Wire.beginTransmission(address);

error = Wire.endTransmission();

if (error == 0)

{

Serial.print("I2C device found at address 0x");

if (address<16)

Serial.print("0");

Serial.print(address, HEX);

Serial.println(" !");

nDevices++;

}

else if (error==4)

{

Serial.print("Unknow error at address 0x");

if (address<16)

Serial.print("0");

Serial.println(address,HEX);

}

}

if (nDevices == 0)

Serial.println("No I2C devices found\n");

else

Serial.println("done\n");

delay(30000);

}

#include

void setup()

{

Wire.begin();

Serial.begin(115200);

Serial.println("\nI2C Scanner");

}

void loop()

{

byte error, address;

int nDevices;

Serial.println("Scanning...");

nDevices = 0;

for(address = 0; address <= 127; address++ )

{

Wire.beginTransmission(address);

error = Wire.endTransmission();

if (error == 0)

{

Serial.print("I2C device found at address 0x");

if (address<16)

Serial.print("0");

Serial.print(address, HEX);

Serial.println(" !");

nDevices++;

}

else if (error==4)

{

Serial.print("Unknow error at address 0x");

if (address<16)

Serial.print("0");

Serial.println(address,HEX);

}

}

if (nDevices == 0)

Serial.println("No I2C devices found\n");

else

Serial.println("done\n");

delay(30000);

}

上述代码上传完成后，打开serial monitor就会看到TOF10120激光传感器的I2C地址。按照数据手册，TOF10120模块的I2C地址为0xA4，由于其寻址采用了高7 bits，这样就变成了0x52，相当于82。

至此，大家已经知道了i2c地址，可以把TOF10120测距传感器模块固定到板子上了。该传感器须固定到适当的高度，以检测车辆和距离。这当然不难，你可以竖一个底部带有螺丝的胶块，我为了方便站了一个充电器的外壳，只要高度满足即可。

下面是本项目的代码，我是按照裁剪的垫子大小来写的，这个尺寸正好就是停车区域的大小。

/* Smart Car Parking system Code

* In this project the TOF10120 Laser Distance Sensor is used for measuring the distance.

*/

#include

// Traffic LED Module interfacing with Arduino Uno or Arduino Nano

int GND_PIN = 5;

int RED_PIN = 4;

int YELLOW_PIN = 3;

int GREEN_PIN = 2;

unsigned char ok_flag;

unsigned char fail_flag;

unsigned short lenth_val = 0;

unsigned char i2c_rx_buf[16];

unsigned char dirsend_flag=0;

int x_mm; // distance in millimeters

float y_inches; // distance in inches

void setup() {

Wire.begin();

Serial.begin(9600,SERIAL_8N1);

printf_begin();

pinMode(GND_PIN, OUTPUT);

pinMode(RED_PIN, OUTPUT);

pinMode(YELLOW_PIN, OUTPUT);

pinMode(GREEN_PIN, OUTPUT);

digitalWrite(GND_PIN, LOW);

digitalWrite(RED_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

}

void loop() {

x_mm = ReadDistance();

// Serial.print(x_mm);

// Serial.println(" mm");

// You can convert millimeters to inches in one of two ways: divide the number of millimeters by 25.4, or multiply the number of millimeters by 0.0394

y_inches = x_mm * 0.0394;

// Serial.print(y_inches);

// Serial.println(" inches");

if ( (y_inches > 0) && (y_inches <= 3) )

{

digitalWrite(RED_PIN, HIGH);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

}

if ( (y_inches > 3) && (y_inches <= 6) )

{

digitalWrite(RED_PIN, HIGH);

delay(200);

digitalWrite(RED_PIN, LOW);

delay(200);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

}

if ( (y_inches > 6) && (y_inches <= 10) )

{

digitalWrite(RED_PIN, LOW);

digitalWrite(YELLOW_PIN, HIGH);

digitalWrite(GREEN_PIN, LOW);

}

if ( (y_inches > 10) && (y_inches <= 20) )

{

digitalWrite(RED_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, HIGH);

}

if ( y_inches > 20 )

{

digitalWrite(RED_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

}

if ( y_inches < 0 )

{

digitalWrite(RED_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

}

}

int serial_putc( char c, struct __file * )

{

Serial.write( c );

return c;

}

void printf_begin(void)

{

fdevopen( &serial_putc, 0 );

}

void SensorRead(unsigned char addr,unsigned char* datbuf,unsigned char cnt)

{

unsigned short result=0;

// step 1: instruct sensor to read echoes

Wire.beginTransmission(82); // transmit to device #82 (0x52), you can also find this address using the i2c_scanner code

// the address specified in the datasheet is 164 (0xa4)

// but i2c adressing uses the high 7 bits so it's 82

Wire.write(byte(addr)); // sets distance data address (addr)

Wire.endTransmission(); // stop transmitting

// step 2: wait for readings to happen

delay(1); // datasheet suggests at least 30uS

// step 3: request reading from sensor

Wire.requestFrom(82, cnt); // request cnt bytes from slave device #82 (0x52)

// step 5: receive reading from sensor

if (cnt <= Wire.available()) { // if two bytes were received

*datbuf++ = Wire.read(); // receive high byte (overwrites previous reading)

*datbuf++ = Wire.read(); // receive low byte as lower 8 bits

}

}

int ReadDistance(){

SensorRead(0x00,i2c_rx_buf,2);

lenth_val=i2c_rx_buf[0];

lenth_val=lenth_val<<8;

lenth_val|=i2c_rx_buf[1];

delay(300);

return lenth_val;

}

/* Smart Car Parking system Code

* In this project the TOF10120 Laser Distance Sensor is used for measuring the distance.

*/

#include

// Traffic LED Module interfacing with Arduino Uno or Arduino Nano

int GND_PIN = 5;

int RED_PIN = 4;

int YELLOW_PIN = 3;

int GREEN_PIN = 2;

unsigned char ok_flag;

unsigned char fail_flag;

unsigned short lenth_val = 0;

unsigned char i2c_rx_buf[16];

unsigned char dirsend_flag=0;

int x_mm; // distance in millimeters

float y_inches; // distance in inches

void setup() {

Wire.begin();

Serial.begin(9600,SERIAL_8N1);

printf_begin();

pinMode(GND_PIN, OUTPUT);

pinMode(RED_PIN, OUTPUT);

pinMode(YELLOW_PIN, OUTPUT);

pinMode(GREEN_PIN, OUTPUT);

digitalWrite(GND_PIN, LOW);

digitalWrite(RED_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

}

void loop() {

x_mm = ReadDistance();

// Serial.print(x_mm);

// Serial.println(" mm");

// You can convert millimeters to inches in one of two ways: divide the number of millimeters by 25.4, or multiply the number of millimeters by 0.0394

y_inches = x_mm * 0.0394;

// Serial.print(y_inches);

// Serial.println(" inches");

if ( (y_inches > 0) && (y_inches <= 3) )

{

digitalWrite(RED_PIN, HIGH);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

}

if ( (y_inches > 3) && (y_inches <= 6) )

{

digitalWrite(RED_PIN, HIGH);

delay(200);

digitalWrite(RED_PIN, LOW);

delay(200);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

}

if ( (y_inches > 6) && (y_inches <= 10) )

{

digitalWrite(RED_PIN, LOW);

digitalWrite(YELLOW_PIN, HIGH);

digitalWrite(GREEN_PIN, LOW);

}

if ( (y_inches > 10) && (y_inches <= 20) )

{

digitalWrite(RED_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, HIGH);

}

if ( y_inches > 20 )

{

digitalWrite(RED_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

}

if ( y_inches < 0 )

{

digitalWrite(RED_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

}

}

int serial_putc( char c, struct __file * )

{

Serial.write( c );

return c;

}

void printf_begin(void)

{

fdevopen( &serial_putc, 0 );

}

void SensorRead(unsigned char addr,unsigned char* datbuf,unsigned char cnt)

{

unsigned short result=0;

// step 1: instruct sensor to read echoes

Wire.beginTransmission(82); // transmit to device #82 (0x52), you can also find this address using the i2c_scanner code, which is available on electroniclinic.com

// the address specified in the datasheet is 164 (0xa4)

// but i2c adressing uses the high 7 bits so it's 82

Wire.write(byte(addr)); // sets distance data address (addr)

Wire.endTransmission(); // stop transmitting

// step 2: wait for readings to happen

delay(1); // datasheet suggests at least 30uS

// step 3: request reading from sensor

Wire.requestFrom(82, cnt); // request cnt bytes from slave device #82 (0x52)

// step 5: receive reading from sensor

if (cnt <= Wire.available()) { // if two bytes were received

*datbuf++ = Wire.read(); // receive high byte (overwrites previous reading)

*datbuf++ = Wire.read(); // receive low byte as lower 8 bits

}

}

int ReadDistance(){

SensorRead(0x00,i2c_rx_buf,2);

lenth_val=i2c_rx_buf[0];

lenth_val=lenth_val<<8;

lenth_val|=i2c_rx_buf[1];

delay(300);

return lenth_val;

}

上面是编程代码，前提是已经下载了 Wire.h 库文件，代码中的距离单位为英寸，欢迎实践和分享。