本項(xiàng)目是一個(gè)采用Traffic LED模塊、Arduino Uno/Nano，以及TOF10120飛行時(shí)間傳感器的工業(yè)級(jí)智能停車系統(tǒng)。項(xiàng)目采用一塊切邊的墊子作為停車區(qū)，先測(cè)量墊子長度，再根據(jù)這個(gè)數(shù)值定義不同距離的代碼，一個(gè)接一個(gè)的點(diǎn)亮（ON）和熄滅（OFF）這些LEDs，以幫助司機(jī)安全停車：

當(dāng)汽車即將進(jìn)入停車區(qū)域時(shí)，綠色LED點(diǎn)亮。然后，黃色LED點(diǎn)亮，提醒司機(jī)即將接近目標(biāo)停車位置，這表明汽車車身已經(jīng)有一半位于停車區(qū)域。

當(dāng)紅色LED開始閃爍時(shí)，警告司機(jī)緩慢行駛并留意，到達(dá)停車點(diǎn)后關(guān)閉汽車，或者繼續(xù)移動(dòng)直到紅色LED停止閃爍。

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作為一個(gè)用以理解停車系統(tǒng)的原型，項(xiàng)目使用的均為廉價(jià)元件。讀者可對(duì)電路進(jìn)行升級(jí)，如改變代碼中的測(cè)量距離數(shù)值，甚至替換電路中的傳感器等，使項(xiàng)目更加實(shí)用。

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ToF10120飛行時(shí)間傳感器

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tof10120激光模塊最大的優(yōu)勢(shì)在于測(cè)距遠(yuǎn)、操作簡(jiǎn)單，程序中僅僅需要通過單片機(jī)給模塊串口發(fā)送命令字符串，就可以向單片機(jī)發(fā)送回距離數(shù)據(jù)。如果發(fā)送自動(dòng)測(cè)距的字符串命令，則模塊會(huì)按照一定頻率自動(dòng)回送數(shù)據(jù)，相關(guān)物理量都可以通過命令字符串設(shè)置。傳感器僅需要串口就可以實(shí)現(xiàn)。

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TOF10120基于Sharp低成本標(biāo)準(zhǔn)CMOS工藝和SPAD技術(shù)，可為自動(dòng)對(duì)焦（AF）提供精確、可重復(fù)的長距離測(cè)量，測(cè)量結(jié)果不受物體反射的影響。主要特點(diǎn)包括：

?采用940nm激光；

?小型陶瓷封裝（20×13.2×2.0mm）；

? 可在室內(nèi)測(cè)量長達(dá)1.8m長度，精度5％；

?測(cè)量距離不受姆堡反射的影響；

?先進(jìn)廣促俄串?dāng)_補(bǔ)償技術(shù)；

?30ms高速測(cè)量；

?單電源供電；

?Txd接口用于設(shè)備控制和數(shù)據(jù)傳送；

?無鉛，符合RoHS指令。

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TOF10120典型測(cè)距范圍為100-1800mm，電源電壓3-5v，消耗電流35mA，兼容Arduino、ESP8266、ESP32等5V和3.3V控制板，適合-20°C to +70°C等室內(nèi)外環(huán)境。

TOF10120支持UART、I2C通訊，1#引腳、2#引腳、3#引腳、4#引腳、5#引腳、6#引腳分別為GND、VDD、RXD、TXD、SDA、SCL。在六個(gè)引腳中，本項(xiàng)目只使用了其中的GND, VDD, SDA, and SCL四個(gè)腳。

根據(jù)數(shù)據(jù)表，TOF10120的I2C地址為0xA4，但尋址采用高7bit即0x52，這相當(dāng)于82。

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交通LED模塊

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該模塊為司機(jī)提供指示，本身帶有限流電阻，無需額外連接電阻器。

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模塊共有4個(gè)公頭，GND引腳鏈接與控制器的GND引腳，或數(shù)字引腳。這樣，5v信號(hào)將熄滅模塊，GND or LOW電平信號(hào)將啟動(dòng)模塊。其中，R標(biāo)號(hào)代表紅色LED, Y標(biāo)號(hào)代表黃色LED，G標(biāo)號(hào)代表綠色LED，高電平信號(hào)時(shí)LED點(diǎn)亮。

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連接電路

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首先，按照電路圖，5V電源由LM7805三端穩(wěn)壓器提供給Arduino Nano，后面需要連接一個(gè)470uF的去耦鋁電解電容器。

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其中，5v穩(wěn)壓連接到Arduino Nano的VIN引腳，TOF10120激光測(cè)距模塊的SCL、SDA引腳分別連接于Arduino板子的A5、A4引腳，電源線鏈接于Arduino板子的5V和接地引腳。

信號(hào)燈LED模塊的GND引腳鏈接到Arduino板子的5號(hào)引腳，紅色LED鏈接到Arduino的4號(hào)引腳，黃色LED連接到3號(hào)引腳，綠色LED連接到2號(hào)引腳。

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PCB設(shè)計(jì)

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接下來，設(shè)計(jì)Arduino Nano PCB開發(fā)板，母頭用于3.3V、12V、5V和接地，左側(cè)作為Vero板用來焊接其他電子元件，Arduino Nano的左右兩側(cè)都設(shè)計(jì)母頭來連接跳線，也可連接傳感器和電子元器件，例如TOF10120傳感器和OLED顯示模塊的I2C引腳。

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最后，將Traffic LED模塊連接于Arduino板子的5、4、3、2引腳，再用公頭連來連接TOF10120傳感器的GND、Vdd、SCL、SDA引線。

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做完上述連接后，就使用下述代碼進(jìn)行I2C尋址：

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#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);

}

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#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);

}

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上述代碼上傳完成后，打開serial monitor就會(huì)看到TOF10120激光傳感器的I2C地址。按照數(shù)據(jù)手冊(cè)，TOF10120模塊的I2C地址為0xA4，由于其尋址采用了高7 bits，這樣就變成了0x52，相當(dāng)于82。

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至此，大家已經(jīng)知道了i2c地址，可以把TOF10120測(cè)距傳感器模塊固定到板子上了。該傳感器須固定到適當(dāng)?shù)母叨?，以檢測(cè)車輛和距離。這當(dāng)然不難，你可以豎一個(gè)底部帶有螺絲的膠塊，我為了方便站了一個(gè)充電器的外殼，只要高度滿足即可。

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下面是本項(xiàng)目的代碼，我是按照裁剪的墊子大小來寫的，這個(gè)尺寸正好就是停車區(qū)域的大小。

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/* Smart Car Parking system Code

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

*/

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#include

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// 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;

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unsigned char ok_flag;

unsigned char fail_flag;

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unsigned short lenth_val = 0;

unsigned char i2c_rx_buf[16];

unsigned char dirsend_flag=0;

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int x_mm; // distance in millimeters

float y_inches; // distance in inches

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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);

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digitalWrite(GND_PIN, LOW);

digitalWrite(RED_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

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}

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void loop() {

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x_mm = ReadDistance();

// Serial.print(x_mm);

// Serial.println(" mm");

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// 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");

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

{

digitalWrite(RED_PIN, HIGH);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

}

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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);

}

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

{

digitalWrite(RED_PIN, LOW);

digitalWrite(YELLOW_PIN, HIGH);

digitalWrite(GREEN_PIN, LOW);

}

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

{

digitalWrite(RED_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, HIGH);

}

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if ( y_inches > 20 )

{

digitalWrite(RED_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

}

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if ( y_inches < 0 )

{

digitalWrite(RED_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(GREEN_PIN, LOW);

}

}

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int serial_putc( char c, struct __file * )

{

Serial.write( c );

return c;

}

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void printf_begin(void)

{

fdevopen( &serial_putc, 0 );

}

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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

}

}

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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;

}

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/* 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;

}

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上面是編程代碼，前提是已經(jīng)下載了 Wire.h 庫文件，代碼中的距離單位為英寸，歡迎實(shí)踐和分享。
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